CN115401156A

CN115401156A - Forging tool and forging method for semi-steel roller

Info

Publication number: CN115401156A
Application number: CN202110594090.1A
Authority: CN
Inventors: 李姣; 曹明; 潘利永; 韩笑宇
Original assignee: TIANJIN HEAVY EQUIPMENT ENGINEERING RESEARCH CO LTD; China First Heavy Industries Co Ltd
Current assignee: TIANJIN HEAVY EQUIPMENT ENGINEERING RESEARCH CO LTD; China First Heavy Industries Co Ltd
Priority date: 2021-05-28
Filing date: 2021-05-28
Publication date: 2022-11-29

Abstract

The invention relates to a forging tool and a forging method for a semi-steel roller, belongs to the technical field of semi-steel forging, and solves the problems of small pressing amount, as-cast state defects of the core of the forged semi-steel roller and unqualified flaw detection in the conventional forging method. The full-coverage type wide flat anvil auxiliary tool comprises an upper flat anvil and a lower flat anvil; the upper flat anvil and the lower flat anvil have the same structure and size and completely cover the blank arranged between the upper flat anvil and the lower flat anvil; the forging method comprises the following steps: step 1, first heating: chamfering and drawing out a blank, pressing a jaw and removing a spindle bottom; step 2, the second heating time: upsetting the blank; step 3, third heating: drawing the blank by adopting a forging tool; step 4, fourth heating: continuously adopting a forging tool to square and process the blank, and chamfering and rounding; step 5, the fifth heating time: and (4) drawing out the roll necks at the two ends of the blank by adopting a WHF method, and discharging to obtain a finished product. The invention can greatly improve the deformation of the semi-steel roller and realize the purpose of improving the forging and compacting effects of the semi-steel ingots.

Description

Forging tool and forging method for semi-steel roller

Technical Field

The invention relates to the technical field of semi-steel forging, in particular to a forging tool and a forging method for a semi-steel roller.

Background

The forged semi-steel roll has the toughness similar to that of steel roll, and the advantages of heat crack resistance and wear resistance of cast iron roll, and is especially suitable for use in rough steel roll and continuous billet mill.

The semi-steel roller material belongs to a material similar to cast iron, the content of C is as high as 1.4-2.2%, steel ingot segregation is serious, the forgeability is poor, and surface cracks are easy to appear in the forging process.

In order to avoid surface damage, the existing semi-steel roller forging assistive device adopts an upper cylindrical surface V-shaped anvil and a lower cylindrical surface V-shaped anvil for compaction, so that the surface cracks at the lap joint of the anvil and the anvil are reduced, and meanwhile, a small rolling reduction has to be adopted, so that the cast state defects of the core of the steel ingot cannot be fully improved, and the phenomena of unqualified flaw detection frequently occur.

Disclosure of Invention

In view of the analysis, the invention aims to provide a forging tool and a forging method for a semi-steel roller, which are used for solving the technical problems of small pressing amount, as-cast defects of the core part of the forged semi-steel roller and unqualified flaw detection in the conventional semi-steel roller forging method.

The purpose of the invention is mainly realized by the following technical scheme:

on one hand, the invention provides a forging tool for a semi-steel roller, which comprises a full-coverage type wide flat anvil auxiliary tool;

the full-coverage type wide flat anvil auxiliary tool comprises an upper flat anvil and a lower flat anvil; the upper flat anvil and the lower flat anvil have the same structure and size and completely cover the blank arranged between the upper flat anvil and the lower flat anvil;

the length of the upper flat anvil and the lower flat anvil is 3000-5000mm.

In one possible design, the width of the upper and lower flat anvils is 1500-2000mm;

the height of the upper flat anvil and the lower flat anvil is 200-300mm.

On the other hand, the invention also provides a forging method of the semi-steel roller, which adopts the forging tool of the semi-steel roller, and the forging method comprises the following steps:

step 1, first heating: chamfering and drawing a blank by using an upper flat anvil and a lower V anvil, pressing a jaw after the blank is drawn, and removing an ingot bottom;

step 2, the second heating time: upsetting blanks by using an upsetting drain pan and an upsetting cover plate;

step 3, the third heating time: after upsetting, adopting a full-coverage type wide flat anvil auxiliary tool to square and process a blank;

step 4, the fourth heating time: continuously adopting a full-coverage type wide flat anvil auxiliary tool to pull the blank, and performing chamfering and rounding treatment on the blank after pulling;

step 5, the fifth heating time: and (3) adopting a WHF method to draw out the roll necks at the two ends of the blank, blanking to obtain a finished product, and preparing to obtain the semi-steel roll.

Further, in step 1, the blank is chamfered and drawn to phi 1000 +/-10 mm by using an upper flat anvil and a lower V anvil, and the pressing jaw phi 600 +/-10 mm.

Further, in step 2, upsetting the blank to H =1400mm to phi 1390mm by using an upsetting bushing and an upsetting cover plate;

the upsetting ratio is 1.5-2.0.

Further, in the step 3, the blank is pulled to the size of \9633,930 +/-10 mm-L =2410mm by using a full-coverage upper and lower wide flat anvil auxiliary tool, the blank is turned into an octagonal shape after the pulling processing, and the blank rolling reduction is 100-150mm when the octagonal shape is turned;

the third firing time comprises 8-9 times of square drawing treatment, and each time is turned for 90 degrees;

in the 8-9-pass draft treatment, the reduction of the first 5 or 6 passes is 30-35%; the rolling reduction of the later pass is determined according to the process size.

Further, in step 4, the blank is pulled to 9633mm and 750 +/-10 mm by continuously adopting a full-coverage wide flat anvil to form a square blank; rounding the square billet to phi 930 +/-10 mm.

Further, in the step 4, in the first 4 times of the multi-time drawing processing, the reduction of each time is 30-35% of the height of the blank;

and rounding from the 5 th pass, wherein the rounding times are 20-32.

Further, in step 5, the anvil width ratio is 0.68-0.77 and the reduction ratio per pass is more than 20%.

Further, in the step 5, the reduction amount is 28-30% of the height of the blank;

the turning is repeated for a plurality of times according to the angle of 0-90-45-90 degrees until the blank becomes cylindrical.

Compared with the prior art, the invention can realize at least one of the following beneficial effects:

(1) In the blank forging process in the prior art, part of the blank is exposed outside the upper anvil and the lower anvil, multi-hammer lapping needs to be carried out, and in the lapping process of each hammer, the tensile stress of the blank is increased, cracks are easy to occur, and the quality of the semi-steel material is poor. The invention provides a full-coverage type wide flat anvil auxiliary tool which can fully cover a blank between an upper flat anvil and a lower flat anvil, zero lap joint of each hammer can be realized during forging, the deformation of a semi-steel roller is further greatly improved, and the purpose of improving the forging and compacting effects of semi-steel ingots is realized.

(2) In the third firing and the fourth firing, a full-coverage type wide flat anvil auxiliary tool is adopted for square drawing and octagonal rounding, the single-pass rolling reduction is 30-35% and is far greater than the rolling reduction of a traditional cylindrical anvil by 10-15%.

In the invention, the technical schemes can be combined with each other to realize more preferable combination schemes. Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and drawings.

Drawings

The drawings are only for purposes of illustrating particular embodiments and are not to be construed as limiting the invention, wherein like reference numerals are used to designate like parts throughout.

FIG. 1 is a schematic view of the structure of an upset drain pan and upset cover plate;

FIG. 2 is a schematic diagram of a semi-steel roll;

FIG. 3 is a schematic view of the overall structure of a full-coverage wide and flat anvil auxiliary tool;

FIG. 4 is a top flat anvil structure of the full-coverage wide flat anvil auxiliary tool;

FIG. 5 is an equivalent strain cloud chart of a core part of a semi-steel roller simulated by using finite elements;

FIG. 6 is a diagram showing a semi-steel roll manufactured according to the present invention;

FIG. 7 is a real object diagram of a semi-steel roller after finishing;

FIG. 8 is a ultrasonic flaw detection result of the back-up roll of the continuous rolling mill produced in example 1;

FIG. 9 shows the results of ultrasonic testing of the back-up rolls of the tandem mill produced in example 2.

Reference numerals:

1-upsetting the cover plate; 2-blank material; 3-upsetting a drain pan; 4-upper flat anvil; 5-lower flat anvil.

Detailed Description

The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form a part hereof, and which together with the embodiments of the invention serve to explain the principles of the invention and not to limit its scope.

The invention provides a forging tool for a semi-steel roller, which comprises a full-coverage type wide flat anvil auxiliary tool, wherein the full-coverage type wide flat anvil auxiliary tool comprises an upper flat anvil 4 and a lower flat anvil 5 which have the same size, as shown in figures 3 and 4; and completely covers the blank 2 placed between the upper flat anvil 4 and the lower flat anvil 5;

specifically, the full-coverage wide flat anvil auxiliary tool provided by the invention can fully cover the blank 2 between the upper flat anvil 4 and the lower flat anvil 5, and zero lap joint per hammer can be realized during forging, so that the deformation of a semi-steel roller is greatly improved, and the purpose of improving the forging and compacting effects of semi-steel ingots is realized.

In order to ensure that the auxiliary materials can be completely covered between the upper flat anvil 4 and the lower flat anvil 5, the length of the upper flat anvil 4 and the length of the lower flat anvil 5 are 3000-5000mm; the width of the upper flat anvil 4 and the lower flat anvil 5 is 1500-2000mm; the height of the upper flat anvil 4 and the lower flat anvil 5 is 200-300mm.

The existing forging tool adopts a cylindrical anvil, and the size of the cylindrical anvil is a 100-degree V-shaped anvil; when the cylindrical anvil is adopted for forging the blank 2, part of the blank 2 is exposed outside the upper anvil and the lower anvil, the cylindrical anvil needs to be overlapped by multiple hammers, and in the overlapping process of each hammer, the tensile stress of the blank 2 is increased, cracks are easy to appear, and the quality of the semi-steel material is poor. The forged semi-steel roller produced by the tool has the advantages that waste products caused by serious cracking are not produced in the forging process, and the flaw detection qualification rate of subsequent products is 100%.

The invention provides a forging method for a semi-steel roller, which specifically comprises the following steps as shown in figure 3 of the invention:

step 1, first heating: chamfering and drawing the forge piece to phi 1000 +/-10 mm by using an upper flat anvil 4 and a lower V anvil, and pressing a jaw phi 600 +/-10 mm; after the blank 2 is drawn out, pressing a jaw, and removing the ingot bottom; wherein, the end surface of a gas cutting clamp is leveled, the clamp is as long as possible, and the ingot bottom is removed;

step 2, second heating: selecting a proper upsetting drain pan 3 and a proper upsetting cover plate 1 (as shown in figure 1) according to the size of the jaw, and upsetting the upsetting drain pan 3 and the upsetting cover plate 1 until the diameter H =1400 mm-phi 1390mm; the upsetting ratio is 1.5-2.0.

The invention can fully destroy the as-cast structure by adopting the upsetting drain pan 3 and the upsetting cover plate 1 and controlling the upsetting ratio within the range of 1.5-2; particularly, for the shaft forging, the drawing ratio of the next drawing process can be improved after upsetting.

Step 3, third heating: drawing a full-coverage upper and lower wide flat anvil auxiliary tool to a size of 9633930 mm-L =2410mm, inverting the octagonal shape, and rolling down by 100-150mm; the hot drawing method comprises 8-9 times, each time is turned for 90 degrees, the rolling reduction of the drawing method of the first 5-6 times is 30-35% of the height of the blank 2, and the rolling reduction of the drawing method of the last 3-4 times is determined according to the process size.

Step 4, the fourth heating time: continuously adopting a full-coverage wide flat anvil to pull the square to 9633750 mm (namely, pull the square to 750mm multiplied by 750 mm), chamfering and rounding to phi 930mm; wherein, the first 4 passes are main deformation passes, the reduction of each pass is 30-35% of the height of the blank 2, and the round is rounded from the 5 th pass to phi 930mm.

Step 5, the fifth heating time: the WHF method (i.e. the wide anvil strong force pressing forging method) lengthens the roll necks at the two ends, and then the finished product, namely the semi-steel roll, is blanked, as shown in figure 2.

Compared with the prior art, the core of the semi-steel roller prepared by the invention has good compaction effect, meets the semi-steel roller flaw detection standard 'technical conditions for forging rigid cast iron rollers' required by users, and has no recorded defects displayed by flaw detection reports; meanwhile, flaw detection is carried out according to the higher standard JB/T4120-2006 (generally used for flaw detection of forged steel supporting rollers, the requirement is higher), and the flaw detection is qualified.

In the step 1, the advantages of chamfering and drawing the forging by using the upper flat anvil 4 and the lower V-shaped anvil are as follows: the pre-drawing length can break the surface as-cast structure, and avoid upsetting and cracking at next firing time; the pressing jaw is convenient for upsetting next fire.

In the step 3, the purpose of controlling the reduction amount of the drawing pass to be between 8 and 9 passes and the first 5 to 6 passes to be between 30 and 35 percent in the third firing pass is to ensure that the defects in the core of the casting can be fully compacted.

It should be emphasized that, in the forging of the blank 2 in the prior art, a part of the blank 2 is exposed outside the upper anvil and the lower anvil, and multi-hammer lapping is required, and in the lapping process of each hammer, the tensile stress of the blank 2 is increased, cracks are easy to occur, and the quality of the semi-steel material is poor.

In the step 3, the full-coverage type wide flat anvil auxiliary tool is adopted for forging, zero overlap joint of each hammer can be realized in the forging process through the full-coverage type wide flat anvil auxiliary tool, and meanwhile, the pass deformation of the semi-steel material can be greatly improved on the basis, so that the forging and compacting effects of the semi-steel material steel ingot are improved.

In the fourth firing order of the step 4, the fourth firing order comprises multi-pass square drawing processing, the first 4 passes are square drawing passes, chamfering and rounding are started from the 5 th pass, and the number of the chamfering and rounding passes is 20-32, specifically, the target size is reached.

In the step 4, the invention continues to adopt a full-coverage wide flat anvil drawing method to 9633750 mm, wherein the first 4 passes are main deformation passes, the reduction of each pass is 30-35% of the height of the blank 2, and the reduction is controlled to be 30-35% because: the larger the rolling reduction, the better the compaction effect on the core part, and the full-coverage type wide flat anvil is characterized in that the pass rolling reduction can reach 30-35%. According to the numerical simulation result and the flaw detection condition of the on-site product, the core defects can be fully compacted by the rolling reduction, and finally the qualified product is obtained.

In the step 3 and the step 4, the full-coverage wide flat anvil auxiliary tool is adopted to produce the square drawing inverted octagon gauge circle, the single-pass rolling reduction is up to 30-35%, and is far greater than the rolling reduction (10-15%) of the traditional cylindrical anvil. Compared with the prior art, the method provided by the invention is adopted for forging production, the former small-reduction deformation forging thinking of the semisteel roller is thoroughly changed, and the characteristics of the full-coverage type wide flat anvil auxiliary tool are utilized, so that the deformation of the semisteel material is greatly improved on the basis of each hammer of zero lap joint of the forging auxiliary tool, and the forging and compacting effects of the semisteel material steel ingot are improved.

In step 5, the anvil width ratio (the ratio of the anvil width B to the blank 2 height H in the case of the wide anvil high reduction forging) is 0.68-0.77, and the reduction ratio (the ratio of the amount of the finger reduction to the blank 2 height) should be greater than 20% per pass. Wherein, the anvil width ratio is controlled in the range, which is beneficial to the compaction of the core defects of the forgings; in addition, the rolling reduction is controlled to be more than 20%, so that the effect change of the center of the forging and the like can be ensured to be large, and the compaction of the defects of the center of the forging is also facilitated.

In the step 5, the rolling amount is 28-30% of the height of the blank 2, and the turning is repeated for a plurality of times according to the angle of 0-90-45-90 degrees. That is, the turning is repeated a plurality of times in a cycle of 0 to 90 to 45 to 90 until the billet becomes cylindrical. The blanking amount of the water gap end is strictly repeated for many times, the size of a finished product is ensured to meet the requirement of a forge piece, and the cutting amount of the waste material at the water gap end is ensured.

The preparation method of the semi-steel roller carries out finite element simulation, and the simulation process is completely carried out according to the process rolling reduction, the overturning angle and the target size. FIG. 5 is a cloud diagram of finite element simulated equivalent strain distribution, wherein the equivalent strain value of the core of the roll body of the semi-steel roll reaches 9, the equivalent strain value of the core of the roll neck reaches 15, which is far greater than the strain value required by the forging penetration introduced in the literature data, and the equivalent strain value of the traditional cylindrical anvil drawing length is between 2 and 3, which proves that the forging method provided by the invention is successful.

It should be noted that, in the above steps 1 to 5, the size of the forged piece is controlled by a hydraulic press computer program, and the size of the blank 2 is controlled by giving a pressing end point at each operation stage.

Example 1

In the embodiment, the forging tool for the semi-steel roller is adopted, wherein the lengths of the upper flat anvil 4 and the lower flat anvil 5 are 4000mm; the width of the upper flat anvil 4 and the lower flat anvil 5 is 1800mm; the height of the upper flat anvil 4 and the lower flat anvil 5 is 300mm.

The forging process of the semi-steel roll provided by the embodiment is as follows:

step 1, first heating: chamfering and drawing the forging to phi 990mm by using an upper flat anvil 4 and a lower V anvil, pressing a jaw to phi 600mm, and removing the ingot bottom after pressing the jaw;

step 2, the second heating time: upsetting a forge piece by using an upsetting drain pan 3 and an upsetting cover plate 1 until H =1400 mm-phi 1390mm; the upsetting ratio was 1.7.

Step 3, the third heating time: adopting a full-coverage wide flat anvil auxiliary tool to draw a square forging; drawing a full-coverage upper and lower wide flat anvil auxiliary tool to a size of 9633930 mm-L =2410mm, inverting the octagonal shape, and pressing down by 120mm; the third hot drawing process comprises 9 processes in total, and each process is turned for 90 degrees; the rolling reduction of the first 5 passes is 30-35%; the reduction of 6-9 passes is determined according to the process size.

Step 4, the fourth heating time: the full-covering wide flat anvil is continuously adopted to square to be at angle of 9633mm and 740mm, and the chamfer is rounded to be at phi 930mm. In the first 4 times, the reduction of each time is 31-33% of the height of the blank 2; and rounding from the 5 th pass to about 27 times until the diameter is 930mm.

Step 5, the fifth heating time: and (4) adopting a WHF method to draw out the roll necks at the two ends of the forging, and blanking to obtain a finished product. When the roll necks at two ends of the forge piece are drawn by the WHF method, the anvil width ratio during drawing is 0.75, and the rolling reduction is 30% of the height of the blank 2; and (4) repeating the overturning for a plurality of times according to the angle of 0-90-45-90 degrees until the blank becomes cylindrical, and preparing the semi-steel roller.

FIG. 6 is a schematic representation of a semi-steel roll prepared in this example, and FIG. 7 is a schematic representation of a semi-steel roll after finishing; and (3) carrying out ultrasonic flaw detection on the semi-steel roll obtained by preparation, wherein the ultrasonic flaw detection result is shown in figure 8, and the flaw detection result shows that no recording defect exists and the flaw detection is qualified.

Example 2

step 2, second heating: upsetting the forge piece by using the upsetting drain pan 3 and the upsetting cover plate 1 until H =1400 mm-phi 1390mm; the upsetting ratio was 1.7.

Step 3, the third heating time: adopting a full-coverage wide flat anvil auxiliary tool to pull square forgings; drawing a full-coverage upper and lower wide flat anvil auxiliary tool to a size of 9633930 mm-L =2410mm, inverting the octagonal shape, and pressing down by 120mm; the third hot drawing process comprises 9 processes in total, and each process is turned for 90 degrees; the rolling reduction of the first 5 passes is 32-35%; the reduction of 6-9 passes is determined according to the process size.

Step 4, fourth heating: continuously adopting a full-coverage wide flat anvil to square to 9633755 mm, and rounding to phi 930mm; in the first 4 times, the reduction of each time is 31-34% of the height of the blank 2; and rounding from the 5 th pass to about 31 times until the diameter is 930mm.

Step 5, the fifth heating time: and (4) adopting a WHF method to draw out the roll necks at the two ends of the forging, and blanking to obtain a finished product. When the roll necks at two ends of the forge piece are drawn by the WHF method, the anvil width ratio during drawing is 0.75, and the rolling reduction is 30% of the height of the blank 2; the turning is repeated for a plurality of times according to the angle of 0-90-45-90 degrees until the blank becomes cylindrical; and preparing the semi-steel roller.

The ultrasonic flaw detection test results of the semi-steel roll prepared in this example are shown in fig. 9, and the flaw detection report shows no recorded flaws and passed flaw detection.

Comparative example 1

The present comparative example provides a method of compacting with a cylindrical V-anvil, comprising the following processes:

traditional cylindrical anvil forging process:

1, fire number: chamfering and drawing out to phi 1000mm, pressing a jaw, and cutting a spindle body at the water gap end to 100 mm;

the 2 nd fire: upsetting to H =1350 mm-phi 1390mm;

fire number 3: adopting a cylindrical surface anvil to elongate until phi is 1000 mm-L =2570mm; in the process of drawing the cylindrical surface anvil, the rolling reduction is controlled to be 100-200mm, so that the rolling reduction is not too large easily, and surface cracking is avoided;

4 th fire number: drawing to phi 930mm, and pre-drawing the roll necks at the two ends to phi 730mm;

fire number 5: and (4) drawing out the roll necks at the two ends, and finishing to obtain a finished product.

In the comparative example, in order to reduce the surface cracks at the lap joint of the anvil and the anvil, a small reduction (10-15%) has to be adopted, so that the core cast state defects of the steel ingot cannot be fully improved, and the flaw detection failure phenomenon occurs frequently.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention.

Claims

1. A forging tool for a semi-steel roller is characterized by comprising a full-coverage type wide flat anvil auxiliary tool;

the full-coverage type wide flat anvil auxiliary tool comprises an upper flat anvil and a lower flat anvil; the upper flat anvil and the lower flat anvil have the same structure and size and completely cover the blank between the upper flat anvil and the lower flat anvil;

the length of the upper flat anvil and the lower flat anvil is 3000-5000mm.

2. The forging tool of the semi-steel roll according to claim 1,

the width of the upper flat anvil and the lower flat anvil is 1500-2000mm;

the height of the upper flat anvil and the lower flat anvil is 200-300mm.

3. A forging method of a semi-steel roll is characterized in that the forging tool of the semi-steel roll is adopted, and the forging method comprises the following steps:

step 1, first heating: chamfering and drawing the blank by using an upper flat anvil and a lower V anvil, pressing a jaw after the blank is drawn, and removing the ingot bottom;

step 2, second heating: upsetting blanks by using an upsetting drain pan and an upsetting cover plate;

step 3, the third heating time: after upsetting, adopting a full-coverage wide flat anvil auxiliary tool to square and process a blank;

step 4, fourth heating: continuously adopting a full-coverage type wide flat anvil auxiliary tool to pull the blank, and performing chamfering and rounding treatment on the blank after pulling;

4. The forging method of semi-steel roll as claimed in claim 3, wherein in step 1, the blank is chamfered and drawn to phi 1000 ± 10mm by using upper flat anvil and lower V anvil, and the pressing jaw phi 600 ± 10mm.

5. The forging method of the semi-steel roll as claimed in claim 3, wherein in the step 2, the blank is upset to H =1400mm to Φ 1390mm by using an upset bushing and an upset cover plate;

the upsetting ratio is 1.5-2.0.

6. The forging method of the semisteel roll according to claim 3, wherein in the step 3, a full-coverage upper and lower wide flat anvil auxiliary tool is used for drawing the blank to 9633930 +/-10 mm-L =2410mm, the blank is turned into an octagonal shape after drawing, and the blank rolling reduction is 100-150mm when the octagonal shape is turned;

the third heating time comprises 8-9 times of square drawing treatment, and each time is turned for 90 degrees;

in the 8-9-pass draft treatment, the reduction of the first 5 or 6 passes is 30-35%.

7. The forging method of the semisteel roll according to claim 3, wherein in the step 4, the blank is continuously pulled to 9633750 +/-10 mm by using a full-coverage wide flat anvil to form a square blank; rounding the square billet to phi 930 +/-10 mm.

8. The forging method of the semi-steel roll according to the claim 7, characterized in that in the step 4, the reduction of each pass is 30-35% of the blank height in the first 4 passes of the multi-pass drawing process;

and rounding from the 5 th pass, wherein the rounding times are 20-32.

9. The method for forging a semi-steel roll according to claim 3, wherein in the step 5, the anvil width ratio is 0.68-0.77 and the reduction ratio per pass is more than 20%.

10. The forging method of a semi-steel roll according to claim 9, wherein in the step 5, the reduction amount is 28-30% of the billet height;

the turning is repeated for a plurality of times according to the angle of 0-90-45-90 until the blank is cylindrical.