CN110193579B

CN110193579B - Integrated forging method for transition section and barrel of hydrogenation reactor

Info

Publication number: CN110193579B
Application number: CN201910600707.9A
Authority: CN
Inventors: 刘凯泉; 周岩; 杨晓禹; 郭义; 赵达; 王勇岗; 李行波
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: 2019-07-04
Filing date: 2019-07-04
Publication date: 2020-11-06
Anticipated expiration: 2039-07-04
Also published as: CN110193579A

Abstract

The invention relates to an integrated forging method for a transition section and a cylinder of a hydrogenation reactor, belongs to the field of machining and forging, and aims to solve the problem that the transition section and the cylinder of the hydrogenation reactor are difficult to integrally machine and close in the prior art, reduce the manufacturing cost and improve the product quality. The forging method comprises the steps of firstly, determining characteristic dimension parameters of a transition section of a cylinder body, and manufacturing a special shell ring necking hammer head according to the characteristic dimension of the transition section; secondly, forging a cylinder, upsetting and punching the steel ingot, drawing out a core rod, and then reaming to reach the size of a part; and finally, pressing down the closing-in for many times, pressing down the workpiece by using the special closing-in hammer head to close the port locally, and pressing down the rotating workpiece for many times to complete the forging forming of the transition section of the barrel. The method realizes the integrated forging of the transition section and the adjacent cylinder body of the hydrogenation reactor, reduces the production cost, improves the production efficiency, reduces the number of welding seams of the whole hydrogenation reactor and improves the working stability of the hydrogenation reactor.

Description

Integrated forging method for transition section and barrel of hydrogenation reactor

Technical Field

The invention relates to the technical field of integrated forging, in particular to an integrated forging method for a transition section and a cylinder body of a hydrogenation reactor.

Background

In recent years, with the vigorous development of national economy of China, the demand of energy and chemical raw material products is more and more large, and the development of hydrogenation reactor equipment towards large-scale, heavy-duty and integrated directions becomes a necessary trend. The reactor equipment is required to work under the harsher high-temperature high-pressure hydrogen-rich condition, and higher requirements are necessarily provided for the operation stability of the hydrogenation reactor. Therefore, the integrated forming technology of the hydrogenation reactor inevitably draws wide attention of the vast petrochemical container design institute.

At present, the manufacturing cost of the traditional manufacturing method of the hydrogenation product forging is high, and the basic reasons are that the manufacturing cost of the forging is high, the manufacturing process is laggard, and the yield of molten steel is low. Therefore, how to manufacture a hydrogenated forging with better quality at lower cost is the primary problem facing the manufacture of hydrogenated products.

Disclosure of Invention

In view of the above analysis, the present invention aims to provide an integrated forging method for a transition section and a cylinder of a hydrogenation reactor, which is used for solving the problems of high manufacturing cost, backward manufacturing process, low yield of molten steel, and poor product quality stability caused by a large number of welding lines in the existing hydrogenation product forging which is separately forged and then welded and formed.

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

an integrated forging method for a transition section and a cylinder body of a hydrogenation reactor comprises the following steps:

step S1: determining the size parameters of a cylinder transition section forging piece according to the size of a hydrogenation reactor;

step S2: a blank making process; sequentially carrying out gas cutting of a water riser, upsetting and punching, core rod drawing, hole expanding and gas cutting chamfering on the steel ingot blank, and forging to obtain a blank transition section;

step S3: determining the structural size of the necking hammer head according to the size parameters of the barrel transition section forge piece determined in the step S1;

step S4: and (3) pressing down and closing up the blank transition section by adopting a closing-up hammer head, and forging the whole barrel transition section forge piece by adopting a mode of pressing down and rotating to close up for multiple times.

Specifically, in step S1, the dimensional parameters of the cylinder transition section forging include: the inner diameter D1 and the outer diameter D2 of the cylinder transition section forging; the length H of the cylinder transition section forging; an inner diameter D3 at the throat end and an outer diameter D4.

Preferably, the closing-in hammer head comprises: the device comprises a cross beam, a first inclined table and a second inclined table; the first inclined table and the second inclined table are symmetrically arranged at two ends of the cross beam and are integrated with the cross beam; a first closing end face is arranged on the first inclined table, and a second closing end face is arranged on the second inclined table; the first closing end surface and the second closing end surface are contacted with the transition section of the blank in the pressing closing process in step S4.

Specifically, the length of a cross beam of the closing-in hammer head is L, and the unit is mm; the length of the first inclined platform and the second inclined platform is l, and the unit is mm; and L is more than D2, L-2L is less than D3, and the units of L, L, D2 and D3 are all millimeters.

Specifically, when the closing-in hammer head is horizontally placed, the inclination angle of the first closing-in end surface and the second closing-in end surface relative to the horizontal direction is alpha, and the alpha range is 20-30 degrees.

Specifically, in step S4, the blank transition section is sequentially pressed downwards in a rotating manner in the order of 0 °, 90 °, 45 °, and 90 °, and 4 hammers are pressed symmetrically, so as to complete the first pass of pressing and closing;

the blank transition section continues to rotate for 22.5 degrees, and the initial position of the second pass is determined; sequentially rotating and pressing downwards according to the sequence of 0 degrees, 90 degrees, 45 degrees and 90 degrees, symmetrically pressing 4 hammers, and finishing the pressing and closing-up action of the second pass;

the blank transition section continues to rotate by 11.25 degrees, and the initial position of the third time is determined; sequentially rotating and pressing downwards according to the sequence of 0 degrees, 90 degrees, 45 degrees and 90 degrees, symmetrically pressing 4 hammers, and finishing the pressing and closing-up action of the third pass;

the blank transition section continues to rotate for 22.5 degrees, and the initial position of the fourth pass is determined; sequentially rotating and pressing downwards according to the sequence of 0 degrees, 90 degrees, 45 degrees and 90 degrees, symmetrically pressing 4 hammers, and finishing the pressing and closing-up action of the fourth pass;

after the fourth pass is pressed down, the closing-in hammer head presses down 16 hammers together, and the blank transition section is closed to obtain the barrel transition section forge piece.

Specifically, in step S2, after the mandrel drawing process is completed, the blank length is H + H, where H is the rolling reduction of the reserved closing hammer head in pressing and closing.

Specifically, when the closing hammer head presses and closes the blank transition section, the pressing amount of each hammer is h.

Specifically, after the broaching process in step S2 was completed, the billet inner diameter was D1 and the billet outer diameter was D2 in mm.

Specifically, in step S4, the billet transition section is mounted on the rotary table and is rotated by the rotary table.

The scheme has at least one of the following beneficial effects:

1. the forging method of the invention reduces the molten steel consumption of a complete set of hydrogenation reactor, thereby reducing the manufacturing cost and shortening the manufacturing period; more importantly, the number of welding seams of the reactor is reduced, and the working stability of the hydrogenation reactor is further improved.

2. According to the method for integrally forging the transition section and the barrel of the hydrogenation reactor, the size of a workpiece is calculated according to needs, and further, the blank is prefabricated into the barrel with the chamfer of the expected size by adopting the working procedures of upsetting, punching, drawing out, reaming, gas cutting, chamfering and the like, and then the barrel is pressed downwards to close up, so that the problem that the closed end of the workpiece is difficult to form is solved, and the accuracy and the machining precision of the machining size and the structural shape can be ensured.

3. When the downward pressing process is carried out, a special closing-in hammer head is adopted, the closing-in hammer head can simultaneously close and press two end points, then a rotary table drives a blank to rotate, the rotary table sequentially rotates through 0 degrees, 90 degrees, 45 degrees and 90 degrees to finish the downward pressing of a first pass, then rotates 22.5 degrees to press 0 degrees, 90 degrees, 45 degrees and 90 degrees to finish a second pass, rotates 11.25 degrees to finish a third pass, and then rotates 22.5 degrees to press 0 degrees, 90 degrees, 45 degrees and 90 degrees to press 4 hammers, and repeatedly presses down for multiple times until the whole closing-in end of the barrel is completely pressed and closed; the necking mode of the invention has simple operation and high structural reliability, can finish uniform necking of the necking end, ensures the quality and precision of the forged piece and simplifies the forging process.

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 claims hereof as well as the appended 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 diagram of forged parts of a transition section and a barrel of a hydrogenation reactor;

FIG. 2 is a cylinder transition section forging piece obtained by integrally forging a transition section and a cylinder of a hydrogenation reactor;

FIG. 3 is a front view of a special closing-up hammer head structure;

FIG. 4 is a side view of a special shell nosing hammer structure;

FIG. 5 is a flow chart of a blank making process;

FIG. 6 is a schematic view of a press-down seam;

FIG. 7 is a flowchart of the closing process.

Reference numerals:

1-a closed end; 2-a cylinder body; 3-closing up the hammer head; 31-a cross beam; 32-a first ramp; 33-a second ramp; 34-a first necked end face; 35-a second necked-in end face; 4-a rotary table.

Detailed Description

The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate preferred embodiments of the invention and together with the description, serve to explain the principles of the invention and not to limit the scope of the invention.

The invention discloses a method for integrally forging a hydrogenation reaction transition section and a cylinder, which comprises the following steps:

step S1: and determining the size of the forging. Determining characteristic dimension parameters of a cylinder transition section forged piece according to the size of the hydrogenation reactor, wherein the cylinder transition section forged piece is a product obtained by integrally forging the transition section and the cylinder of the hydrogenation reactor, and the cylinder transition section forged piece comprises: a closed end 1 and a cylinder body 2. Wherein, the inner diameter of the cylinder body 2 is D1, and the outer diameter is D2; the integral length H of the cylinder transition section forging; the inner diameter of the necking end 1 is D3, the outer diameter is D4, and the integrally designed cylinder transition section forging structure is shown in figure 2. A schematic diagram of a segment forged hydrogenation transition section and barrel section commonly used in the prior art is shown in FIG. 1.

Step S2: and (5) blank making. As shown in fig. 5, the blank is forged into an open blank transition section through the steps of gas cutting a riser, upsetting and punching, drawing out a mandrel, reaming, gas cutting, chamfering and the like.

The blank making process comprises the following steps:

firstly, gas cutting a water riser: in order to ensure the working stability of the hydrogenation product forging in a high-temperature and high-pressure hydrogen-rich environment, a water riser of a steel ingot is cut off in a gas cutting mode, and only a part with excellent quality is reserved.

Secondly, upsetting and punching: and (3) upsetting and punching the steel ingot after the gas cutting of the water feeder head to obtain a cylindrical blank with smaller length and diameter and thicker thickness after upsetting and punching, as shown in fig. 5.

Thirdly, drawing out the core rod: in order to reserve the rolling reduction when the necking hammer head 3 is adopted to press and close the necking in the subsequent process, the blank core rod after upsetting and punching is drawn to be H + H, the length of the blank after the core rod is drawn is larger than the length H of the expected manufactured forging, and H is the rolling reduction height of the special necking hammer head rotary forging in the fourth step.

Fourthly, reaming the blank: after the mandrel bar is drawn out, the billet is rolled by a bar or shell ring former to an inside diameter of D1 and an outside diameter of D2.

Fifthly, gas cutting and chamfering: and (4) performing gas cutting chamfering on the excircle of the end surface of one side of the cylinder transition section forge piece to finish the prefabrication of the forging stock of the whole cylinder transition section forge piece. And determining the size parameters of the gas cutting chamfer according to the size characteristics of the expected forged cylinder transition section forging.

And (3) finishing the forging blank prefabrication of the integral barrel transition section forge piece through the blank manufacturing process to obtain a blank transition section.

Step S3: and (5) designing the structural size of the special closing-in hammer head 3 according to the size of the cylinder transition section forge piece designed in the step S1.

Preferably, the structure of the closing-in hammer head 3 includes: crossbeam 31, first sloping bench 32 and second sloping bench 33, and set up first binding off terminal surface 34 on the first sloping bench 32, set up second binding off terminal surface 35 on the second sloping bench 33.

The beam 31 is a long rectangular parallelepiped structure, the first inclined platform 32 and the second inclined platform 33 are symmetrically disposed at two ends of the beam 31, that is, the first inclined platform 32 and the second inclined platform 33 are symmetrical with respect to a central cross section of the beam 31 in a length direction, and the beam 31, the first inclined platform 32 and the second inclined platform 33 are an integral structure, as shown in fig. 3.

The size characteristics of the closing-up hammer head 3 include the length L and the width W of the cross beam 31 of the closing-up hammer head 3, the length L of the first inclined table 31 and the second inclined table 32 at the two ends, and the inclination angle α of the first closing-up end face 34 and the second closing-up end face 35. When the closing-in hammer head 3 is placed horizontally, that is, when the cross beam 31 is kept horizontal, the included angle between the first closing-in end surface 34 and the second closing-in end surface 35 and the horizontal direction is α, and the length L and the width W of the cross beam 31 are the length and the width of the closing-in hammer head 3, see fig. 3 and 4.

Specifically, in order to ensure that the first closing-in end face 34 and the second closing-in end face 35 of the closing-in hammer head 3 can both be in contact with the circumference outer edge of the forging closing-in end 1 after the gas cutting chamfer, the requirements are as follows: the length L of the closing-in hammer head 3 is larger than the outer diameter D2 of the cylinder forging, namely L is larger than D2; the distance between the first inclined platform 32 and the second inclined platform 33 of the closing-in hammer head 3 is smaller than the inner diameter D3 of the closed end of the cylinder forging, namely L-2L is smaller than D3.

Specifically, in order to realize accurate closing-in gradient of the closing-in end 1, downward pressure of the closing-in hammer head 3 on the closing-in end can enable the closing-in end 1 to be stressed to incline towards the center of the cylinder, meanwhile, crush damage to the cylinder structure caused by downward pressure is avoided, and distortion of the shape of the closing-in end 1 is avoided, an included angle between the direction of downward pressure of the closing-in hammer head 3 on the closing-in end 1 and the side surface of the cylinder cannot be too large or too small, the cylinder is easy to distort if the downward pressure is too large, and the closing-in purpose cannot be achieved if the downward pressure is too small, so that the included angle α between the first closing-in end surface 34 and the second closing-in end surface 35 and the horizontal direction is required to be within an optimal range, and therefore, through model simulation and repeated experiments, the included angle. As shown in particular in figure 3.

Step S4: and finally, rotationally forging and closing the opening by using a special closing-in hammer head 3 to finish the integral forging of the integral cylinder transition section forged piece, wherein the schematic drawing of pressing and closing the opening is shown in fig. 6, and the cylinder transition section forged piece obtained after closing the opening is shown in fig. 2.

Adopt above-mentioned dysmorphism binding off tup 3 to push down the binding off to the blank changeover portion in forging process, first binding off terminal surface 34, the second binding off terminal surface 35 of binding off tup 3 contact with the both ends of the circular port of binding off end 1 respectively, inwards press the barrel of 1 chamfer position of binding off end, make barrel 2 incline to the axis direction at the inner wall of 1 position of binding off end.

When closing in, as shown in fig. 6, the closing in end 1 of blank changeover portion is up, puts on revolving platform 4, and the rotation through revolving platform 4 drives the blank changeover portion rotatory, and closing in tup 3 does not rotate, only can reciprocate, accomplishes and pushes down the action, and after the blank changeover portion rotated certain angle under the drive of revolving platform 4, closing in tup 3 pushed down once more, pushes down the binding in completion to the blank changeover portion many times, obtains the barrel changeover portion forging that the integration was forged and is accomplished.

Specifically, in the closing-in process of the closing-in hammer head 3, the central line of the closing-in hammer head 3 is kept to be coincident with the central axis of the blank transition section as much as possible, the consistency in the pressing-down process is kept, and the closing-in of the blank transition section is uniform. In order to avoid the repeated pressing-down condition at the same position, the rotary table 4 always rotates towards the same direction in the process of pressing down and closing up the shell nosing hammer 3 for multiple times, and when the shell nosing hammer 3 presses down the blank transition section for closing up, the rotary table 4 does not rotate.

Specifically, when the closing-in hammer head 3 is pressed down, the rotary table 4 rotates 0 degrees, 90 degrees, 45 degrees and 90 degrees in sequence, and the closing-in hammer head 3 presses down four hammers to finish the first-pass pressing-down closing-in.

The first pressing process comprises the following steps: when the rotary table 4 is positioned at the initial position, the closing-in hammer head 3 presses down the first hammer; the revolving platform 4 rotates by 90 degrees, and the closing-in hammer head 3 presses down the second hammer; the rotary table 4 continues to rotate for 45 degrees, and the closing-in hammer head 3 presses down the third hammer; the rotary table 4 continues to rotate by 90 degrees, and the closing-in hammer head 3 presses down the fourth hammer; and finishing the first pressing and necking.

After the first pass is completed, the closing-in hammer head 3 presses down the four hammers to obtain eight pressing points, and the eight pressing points after the closing-in is completed in the first pass are uniformly distributed on the circumference of the closing-in end 1, as shown in fig. 7.

Specifically, before the second-pass necking-down operation, the rotary table 4 drives the blank transition section to continue rotating by 22.5 degrees, and the blank transition section is used as the initial position of the second pass. Then, the pressing-down is sequentially rotated and pressed downwards according to the sequence of 0 degrees, 90 degrees, 45 degrees and 90 degrees, 4 hammers are symmetrically pressed, and the pressing-down and necking-down actions in the second pass are completed.

Specifically, before the third pressing-down closing-in operation is performed, the rotary table 4 drives the blank transition section to continue rotating by 11.25 degrees, and the blank transition section is used as the initial position of the third pass. Then, the pressing is sequentially rotated and pressed downwards according to the sequence of 0 degrees, 90 degrees, 45 degrees and 90 degrees, 4 hammers are symmetrically pressed, and the third pressing and closing-down action is completed.

Specifically, before the fourth-pass necking-down operation, the rotary table 4 drives the blank transition section to continue rotating by 22.5 degrees, and the blank transition section is used as the initial position of the fourth pass. And then, sequentially rotating and pressing downwards according to the sequence of 0 degrees, 90 degrees, 45 degrees and 90 degrees, symmetrically pressing 4 hammers, and finishing the downward pressing and closing-in action of the fourth pass.

After the fourth time of pressing down is completed, the closing-up hammer 3 is pressed down for 16 times totally, and the end point is pressed down for 32 times totally, so that the whole closing-up end 1 is pressed down and closed up. By adopting the method for pressing and closing the opening, the situation that the same position is repeatedly pressed can be avoided, and the closing uniformity of the transition section of the blank is ensured. Generally, the fourth pass is completed by pressing down and closing up, the closing-up hammer head 3 presses down 16 hammers, then the closing up of the transition section of the blank is completed, the integrated forging of the transition section of the hydrogenation reactor and the adjacent cylinder is completed, and the forging of the transition section of the cylinder is obtained. The flow chart of closing with the closing hammer 3 is shown in fig. 7.

Considering that the larger the circumferential perimeter of the transition section of the blank is, the larger the width W of the necking-in head 3 is to ensure that the necking-in is completed after 16 hammers are pressed down. The width W of the closing-in hammer head 3 is designed according to the outer diameter D2 of the barrel of the blank transition section, and closing-in is completed after 16 hammers of four passes are completed. That is to say, it is necessary to ensure that the width W of the closing-up hammer head 3 is greater than the arc length of the closing-up end 1 corresponding to 11.25 °, that is, the width W of the closing-up hammer head 3 is greater than 1/32 of the circumference of the closing-up end 1, so as to ensure that the closing-up of the transition section of the blank is completed after 16 hammers are pressed down.

It should be noted that, in order to maintain the radian of the closing-in end 1, the width of the closing-in hammer head 3 should not be too large. Therefore, under the condition that the circumference of the closing end 1 is long and the width W of the closing hammer 3 is small, the situation that the blank transition section is not closed completely after the fourth-pass downward closing action is completed can occur.

At this time, the rotational depression of the second wheel is continued. Before the second round of rotation is started to press down, the rotary table 4 is firstly rotated by a smaller angle beta which is smaller than 11.25 degrees, the initial position is redefined, and then the pressing process is repeated to finish the four-pass pressing action of the second round. Namely, the 16 th hammer is rotated by a smaller angle beta to determine the initial position of the second wheel for pressing down, and then the second wheel is sequentially rotated and pressed down according to the sequence of 0 degrees, 90 degrees, 45 degrees and 90 degrees to symmetrically press 4 hammers, so that the fifth pass of pressing-down closing-up action is completed. And rotating 22.5 degrees to distribute the hammers according to the conditions of 0 degree, 90 degrees, 45 degrees and 90 degrees, symmetrically pressing 4 hammers by rotating 11.25 degrees, symmetrically pressing 4 hammers by rotating 22.5 degrees and symmetrically pressing 4 hammers by rotating 22.5 degrees.

Specifically, the whole closing-in process is completed by pressing down one pass in the above mode, the pressing amount H of each hammer of the special closing-in hammer head is obtained, after the closing-in hammer head 3 presses down and closes up, the length of the obtained complete cylinder transition section forged piece is H, the inner diameter of the closing-in end 1 is D3, and the outer diameter is D4.

Specifically, the unit of the inner diameter D1 and the outer diameter D2 of the cylinder 2, the inner diameter D3 and the outer diameter D4 of the necking end 1, the length H of the forged piece, the length L and the width W of the necking hammer head 3, the length L of the first inclined table and the second inclined table and the reduction H of the cylinder transition section forged piece are millimeters.

Specifically, after the closing-in is completed, the cylinder transition section forging piece needs to be subjected to finish machining. Therefore, in the process of forging manufacture, machining allowance can be properly set for subsequent finish machining.

The forming process is numerically simulated by adopting the scheme, and the simulation result shows that the integral forging technology of the transition section and the adjacent cylinder body of the hydrogenation reactor can realize the integral forging of the transition section and the adjacent cylinder body of the hydrogenation reactor.

The invention adopts the technical scheme that the method firstly determines the characteristic dimension parameters of the integral cylinder transition section forge piece according to the part dimension, designs the special closing-up hammer head according to the characteristic dimension, completes the blank making after the steel ingot is subjected to upsetting, drawing out, reaming and gas cutting chamfering, and finally uses the closing-up hammer head to rotationally forge the closing-up, thereby realizing the integral forging of the transition section and the adjacent cylinder body of the hydrogenation reactor, greatly reducing the molten steel consumption of the complete set of hydrogenation reactor and the number of welding seams of the reactor, reducing the manufacturing cost, shortening the manufacturing period and more importantly improving the service stability of the hydrogenation reactor.

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. An integrated forging method for a transition section and a cylinder body of a hydrogenation reactor is characterized by comprising the following steps:

step S3: determining the structural size of the necking hammer head (3) according to the size parameters of the cylinder transition section forge piece in the step S1;

step S4: a closing-in hammer head (3) is adopted to press down and close up the blank transition section, and the forging of the barrel transition section forging is completed in a mode of pressing down and rotating to close up for multiple times;

in step S3, the closing hammer head (3) includes: a cross beam (31), a first ramp (32) and a second ramp (33); the first inclined table (32) and the second inclined table (33) are symmetrically arranged at two ends of the cross beam and are integrated with the cross beam (31) into a whole; a first closing end face (34) is arranged on the first inclined table (32), and a second closing end face (35) is arranged on the second inclined table (33); the first closing end face (34) and the second closing end face (35) are contacted with the blank transition section in the pressing closing process in the step S4;

in the forging process, the closing-in hammer head (3) is adopted to press down the blank transition section for closing in, and a first closing-in end face (34) and a second closing-in end face (35) of the closing-in hammer head (3) are respectively contacted with a circular port of the closing-in end (1);

in the step S4, the blank transition section sequentially rotates and presses down in the order of 0 °, 90 °, 45 °, 90 °, and symmetrically presses 4 hammers, thereby completing the first pass of pressing and closing down; the blank transition section continues to rotate for 22.5 degrees, and the initial position of the second pass is determined; sequentially rotating and pressing downwards according to the sequence of 0 degrees, 90 degrees, 45 degrees and 90 degrees, symmetrically pressing 4 hammers, and finishing the pressing and closing-up action of the second pass; the blank transition section continues to rotate by 11.25 degrees, and the initial position of the third time is determined; sequentially rotating and pressing downwards according to the sequence of 0 degrees, 90 degrees, 45 degrees and 90 degrees, symmetrically pressing 4 hammers, and finishing the pressing and closing-up action of the third pass; the blank transition section continues to rotate for 22.5 degrees, and the initial position of a fourth pass is determined; sequentially rotating and pressing downwards according to the sequence of 0 degrees, 90 degrees, 45 degrees and 90 degrees, symmetrically pressing 4 hammers, and finishing the pressing and closing-up action of the fourth pass; after the fourth pass is pressed down, the closing-in hammer head (3) presses down 16 hammers together, and the blank transition section is closed to obtain the barrel transition section forge piece.

2. The forging method for the transition section and the cylinder of the hydrogenation reactor integrally according to claim 1, wherein in the step S1, the dimensional parameters of the cylinder transition section forging comprise: the inner diameter D1 and the outer diameter D2 of the cylinder (2) of the cylinder transition section forging piece; the length H of the cylinder transition section forging; an inner diameter D3 and an outer diameter D4 of the female end (1).

3. The forging method for the transition section and the cylinder of the hydrogenation reactor integrally according to claim 2, wherein the length of a cross beam (31) of the necking hammer head (3) is L; the length of the first inclined platform (32) and the second inclined platform (33) is l; and L is more than D2, L-2L is less than D3, and L, L, D2 and D3 are all in mm.

4. The forging method for the transition section and the barrel of the hydrogenation reactor integrally according to claim 2 or 3, wherein when the necking hammer head (3) is placed horizontally, the inclination angle of the first necking end face (34) and the second necking end face (35) relative to the horizontal direction is alpha, and the alpha ranges from 20 degrees to 30 degrees.

5. The forging method for the transition section and the cylinder of the hydrogenation reactor integrally according to claim 2, wherein in the step S2, after the mandrel drawing-out process is completed, the blank length is H + H, where H is the pressing amount of the reserved closing hammer (3) when pressing and closing.

6. The forging method for the transition section and the barrel of the hydrogenation reactor integrally according to claim 5, wherein the reduction amount of each hammer is h when the necking hammer head (3) performs downward pressing and necking on the blank transition section.

7. The forging method for the transition section and the cylinder of the hydrogenation reactor integrally as claimed in claim 6, wherein after the hole expanding process in the step S2 is completed, the inner diameter of the blank is D1; the outer diameter is D2.

8. The forging method for the transition section and the cylinder of the hydrogenation reactor integrally as claimed in claim 1, wherein in the step S4, the billet transition section is mounted on a rotary table (4) and is driven to rotate by the rotary table (4).