CN112916776A

CN112916776A - Full-coverage forging attachment and forging method

Info

Publication number: CN112916776A
Application number: CN202011601542.6A
Authority: CN
Inventors: 曹明; 金嘉瑜; 李姣; 刘东海
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: 2020-12-29
Filing date: 2020-12-29
Publication date: 2021-06-08
Anticipated expiration: 2040-12-29
Also published as: CN112916776B

Abstract

The invention discloses a full-coverage forging attachment and a forging method, belongs to the technical field of forging, and solves the problems of surface cracking and forging core compaction caused by large deformation in the forging process of a high-alloy forging in the prior art. The forging attachment comprises an upper cutting board and a lower cutting board which are oppositely arranged, wherein a blank is placed between the upper cutting board and the lower cutting board, and the projection of the upper cutting board and the lower cutting board on the blank completely covers the blank. The forging method comprises the following steps: squaring a first pass to enable an initial blank to reach a target size of the first pass; squaring the blank for the second pass to enable the initial blank after the first pass to reach the target size of the second pass; and (4) performing multi-pass square drawing and chamfering, and drawing to the target diameter of the finished product forged piece to obtain the finished product forged piece. The full-coverage forging attachment and the forging method can be used for forging forgings.

Description

Full-coverage forging attachment and forging method

Technical Field

The invention relates to the technical field of forging, in particular to a full-coverage type forging attachment and a forging method.

Background

The forging and compacting technology generally comprises a JTS method, an FM method, a KD method, a WHF method and the like, the anvil type of the forging attachment is generally an upper flat anvil, a lower flat anvil and an upper V-shaped anvil, the width ratio of the anvil is controlled in a certain range, lap joints exist between the anvils, a forging piece at the lap joints is easy to cause surface cracking due to shearing deformation, and in order to avoid the surface cracking phenomenon, the rolling reduction and the compacting effect of the center of the forging piece are inevitably greatly influenced.

Disclosure of Invention

In view of the above analysis, the present invention aims to provide a full-coverage forging attachment and a forging method, which solve the problem of surface cracking caused by large deformation in the forging process of high alloy forgings in the prior art.

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

the invention provides a full-coverage forging accessory which comprises an upper cutting board and a lower cutting board which are oppositely arranged, wherein a blank is placed between the upper cutting board and the lower cutting board, and the projection of the upper cutting board and the lower cutting board on the blank completely covers the blank.

Furthermore, the fully-covered forging jig is particularly suitable for forging blanks of more than 20t (for example, 20-80 t).

Further, the length of the upper chopping board and the lower chopping board is larger than or equal to the length of a forged piece after forging compaction fire.

Further, the length ratio of the upper chopping board to the lower chopping board to the forge piece after forging compaction fire is 1.1-1.2.

Further, the width of the upper anvil and the lower anvil is greater than or equal to the product of the diameter of the initial blank and the coefficient of broadening.

TABLE 1 reduction and spreading factor

Reduction of first pass of forging	Coefficient of broadening
		25％	1.13
30％	1.16
		35％	1.19

Further, the determination of the thickness of the upper anvil plate comprises the steps of:

step a: determining an initial thickness;

step b: according to the contact area of the upper cutting board and the output end of the forging device, the contact area of the initial blank and the upper cutting board, the pressure of the forging device and the material of the upper cutting board, simulating by adopting finite element analysis software to generate an upper cutting board initial model, and analyzing a stress cloud chart of the upper cutting board initial model to obtain the maximum value of the stress borne by the upper cutting board;

step c: judging whether the maximum stress value of the upper chopping board exceeds the yield strength of the material of the upper chopping board;

if the maximum value of the stress borne by the upper chopping board is 1.5 times smaller than or equal to the yield strength of the material of the upper chopping board 1, the initial thickness in the step is the thickness of the upper chopping board;

and (c) if the maximum value of the stress borne by the upper anvil plate is 1.5 times larger than the yield strength of the material of the upper anvil plate, increasing the initial thickness in the step a, and repeating the steps a to b.

Further, the thickness of the lower anvil plate is greater than or equal to the difference between the upper limit of the hydraulic press and the thickness of the upper anvil plate and the thickness of the finished forging.

The invention also provides a full-coverage forging method, which comprises the following steps:

step 1: mounting the forging attachment on a forging device (e.g., a hydraulic press) with the initial blank placed between an upper anvil and a lower anvil;

step 2: square drawing for the first pass, setting a first pass target size according to the first pass reduction, and pressing down an upper chopping board to enable an initial blank to reach the first pass target size, and turning for 90 degrees;

and step 3: square drawing for a second pass, setting a target size of the second pass according to the reduction of the second pass, and rolling down the upper chopping board to ensure that the initial blank after the first pass reaches the target size of the second pass, and turning for 90 degrees;

and 4, step 4: carrying out multi-pass square drawing (for example, 4-8 passes), calculating the target size of each pass according to the reduction of each pass, carrying out reduction on an upper chopping board, turning over 90 degrees after each time of square drawing, and carrying out next time of square drawing to obtain a square-drawn forged piece;

and 5: chamfering, chamfering and chamfering, chamfering with an angle of 22.5 degrees, drawing to the target diameter of the finished product forged piece, and obtaining the finished product forged piece.

Further, the reduction amount after the third pass is reduced compared to the reduction amount of the first pass and the reduction amount of the second pass.

Furthermore, the first pass reduction amount is 30-35%, the second pass reduction amount is 35-40%, and the third pass and later reduction amounts are 20-25%.

Further, the reduction in the even-numbered pass between adjacent passes is generally higher than in the previous odd-numbered pass.

Further, the diameter ratio of the side length of the forged piece after drawing in the step 4 to the finished forged piece is 0.9-0.95.

Further, the step 1 includes the following steps:

step 11: mounting the upper chopping board at the output end of the hydraulic press, and lifting the upper chopping board to the upper limit of the forging device;

step 12: placing a lower chopping board on a walking board of the forging device, and aligning the upper chopping board and the lower chopping board;

step 13: opening the walking board, staggering the lower chopping board and the upper chopping board, and placing the initial blank on the lower chopping board;

step 14: realigning the upper chopping block and the lower chopping block to ensure that the initial blank is placed between the upper chopping block and the lower chopping block, and the axis of the initial blank is superposed with the central line of the upper chopping block or the lower chopping block to avoid the occurrence of unbalance loading phenomenon in the forging process.

Further, the maximum deformation force of the initial blank is equal to the forging attachment area (length of the upper anvil plate x width of the upper anvil plate or length of the lower anvil plate x width of the lower anvil plate) and the yield stress σ of the initial blank material at the lowest forging temperature, strain rate 0.01_sThe maximum working pressure of the forging apparatus is greater than or equal to the maximum deformation force of the initial blank.

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

a) according to the full-coverage type forging accessory provided by the invention, the areas of the upper chopping block and the lower chopping block are large enough, the blank can be completely covered, and the lapping between the chopping blocks does not exist in the forging process, so that the surface cracking phenomenon caused by large deformation in the forging process of a high-alloy forging piece can be effectively relieved, and the surface and core quality of the forging piece is improved.

b) According to the full-coverage forging attachment provided by the invention, according to the law of minimum resistance, the middle part of the blank is repeatedly widened and deformed in the width direction in the drawing process, and the friction force is rapidly increased due to the full-coverage contact of the attachment and the forging in the length direction, so that the deformation of the forging in the length direction is limited.

c) The full-coverage forging attachment provided by the invention is based on the full-coverage characteristic, the transverse widening of the blank is larger when each hammer is pressed down, and the characteristic can be utilized to realize limit deformation, so that the surface can not be cracked, and the reduction per pass can be greatly increased.

d) According to the full-coverage forging attachment provided by the invention, due to the adoption of the full-coverage forging attachment, the transverse widening of the forged piece is large in the chamfering and rounding process, and even if the side length of the forged piece after being pulled out is smaller than the diameter of the finished forged piece, the required diameter of the finished forged piece can be obtained through the transverse widening, so that the rapid rounding can be realized, the limit deformation can be realized, and the forging compaction effect is improved. It should be noted that, in the prior art, because the chopping block has an overlap joint phenomenon in the chamfering and rounding process, a large transverse widening cannot be achieved, and once the reduction is too large, the forge piece is folded, so that the side length of the forge piece after being pulled out by adopting the existing forging method must be larger than or equal to the diameter of the finished forge piece.

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 the particular invention and are not to be construed as limiting the invention, wherein like reference numerals are used to designate like parts throughout the figures.

FIG. 1 is a schematic structural diagram of a fully-covered forging attachment according to an embodiment of the present invention;

FIG. 2 is a line graph of a first pressing amount and a coefficient of broadening in a full mantle forging apparatus according to an embodiment of the present invention;

fig. 3 is a flowchart illustrating chamfering in the full-coverage forging method according to the second embodiment of the present invention.

Reference numerals:

1-upper chopping block; 2-drawing the square rear forging; 3-cutting the chopping board; 4-initial blank.

Detailed Description

The preferred invention will now be described in detail with reference to the accompanying drawings, which form a part hereof, and which together with the description serve to explain the principles of the invention.

Example one

The present embodiment provides a fully-covered forging attachment, see fig. 1, comprising an upper anvil 1 and a lower anvil 3 arranged opposite to each other, a blank being placed between the upper anvil 1 and the lower anvil 3, the projection of the upper anvil 1 and the lower anvil 3 on the blank completely covering the blank.

The fully-covered forging jig is particularly suitable for forging a billet of 20t or more (for example, 20 to 80 t).

Compared with the prior art, the full-coverage type forging attachment provided by the embodiment has the advantages that the areas of the upper chopping block 1 and the lower chopping block 3 are large enough, blanks can be completely covered, and in the forging process, the lapping between the chopping blocks does not exist, so that the surface cracking phenomenon caused by large deformation in the forging process of a high-alloy forging can be effectively relieved, and the surface and core quality of the forging is improved; meanwhile, according to the law of minimum resistance, the middle part of the blank is repeatedly widened and deformed in the width direction in the drawing process, and the friction force is rapidly increased in the length direction due to the fact that the accessory is in full-covering contact with the forge piece, so that the deformation of the forge piece in the length direction is limited; in addition, based on the characteristic of full coverage, the transverse widening of the blank is large when each hammer is pressed down, and the characteristic can be used for realizing limit deformation, so that the surface is not cracked, and the reduction per pass can be greatly increased.

For the determination of the length of the upper anvil 1 and the lower anvil 3, exemplarily, the broadening coefficient is determined according to the pressing amount, the length L of the upper anvil 1 and the lower anvil 3 is greater than or equal to the length of the forge piece after forging and compacting fire, and exemplarily, the length ratio of the upper anvil 1 and the lower anvil 3 to the forge piece after forging and compacting fire is 1.1-1.2. It should be noted that the forging compaction heat is a heat mainly used for compacting the core of the forging, and is usually the penultimate heat or the penultimate heat of the finished forging, and one heat or two heats after the forging compaction heat are used for final forming of the forging.

For the determination of the width of upper anvil 1 and lower anvil 3, upper anvil 1 and lower anvil 3 have, for example, a width W greater than or equal to the product of diameter a and coefficient of broadening b of initial blank 4. Through reasonable in design's

upper chopping block

1 and 3 sizes of lower chopping block, can guarantee upper chopping block 1 and lower chopping block 3 and the horizontal and fore-and-aft full contact of blank or forging in the free forging process. It should be noted that the broadening coefficient can be obtained according to the rolling reduction of each pass, the rolling reduction of the first pass has a linear relationship with the broadening coefficient, the following lists the corresponding values of the rolling reduction and the broadening coefficient of a plurality of common first passes, see table 1, if the rolling reduction of the first pass is not in table 1, a linear graph (see fig. 2) of the first rolling reduction and the broadening coefficient can be made by adopting the numerical fitting of table 1, and the corresponding broadening coefficient can be found according to the rolling reduction of the first pass through the linear graph.

TABLE 1 reduction and spreading factor

Likewise, for the thickness determination of the above-mentioned attachment, the thickness determination of the upper anvil 1 and the lower anvil 3 is different due to the different forces applied to the upper anvil 1 and the lower anvil 3.

For the upper chopping board 1, the upper chopping board 1 needs to be connected with the output end of the forging device, and because the area of the output end of the forging device is smaller than that of the upper chopping board 1, the deformation of the upper chopping board 1 is easily caused in the forging process, and therefore, the thickness H of the upper chopping board 1_upDepending on the pressure of the forging device, the yield strength of the material of the attachment and the contact area of the initial blank 4 with the upper anvil 1, the yield strength of the material of the upper anvil attachment is not exceeded and a safety factor of more than 1.5 is maintained. Thickness of the upper chopping block 1H_upThe determination comprises the following steps:

step a: determining an initial thickness;

step b: according to the contact area between the upper cutting board 1 and the output end of the forging device, the contact area between the initial blank 4 and the upper cutting board 1, the pressure of the forging device and the material of the upper cutting board 1, simulating by adopting finite element analysis software to generate an initial model of the upper cutting board 1, and analyzing a stress cloud chart of the initial model of the upper cutting board 1 to obtain the maximum value of the stress borne by the upper cutting board 1;

step c: judging whether the maximum stress value of the upper chopping board 1 exceeds the yield strength of the material of the upper chopping board 1;

if the maximum value of the stress borne by the upper chopping board 1 is 1.5 times smaller than or equal to the yield strength of the material of the upper chopping board 1, the initial thickness in the step a is the thickness of the upper chopping board 1;

and (c) if the maximum stress value of the upper anvil plate 1 is 1.5 times larger than the yield strength of the material of the upper anvil plate 1, increasing the initial thickness in the step a, and repeating the steps a to b.

For the thickness of the lower cutting board 3, the lower cutting board 3 is placed on a walking platform of the forging device, and as the area of the walking platform is larger than that of the lower cutting board 3, the stress of the lower cutting board 3 is uniform, the mechanical strength of the lower cutting board 3 is not required to be considered in the thickness design of the lower cutting board 3, but the thickness of the lower cutting board 3 can meet the forging requirement of a blank, and therefore, the thickness of the lower cutting board 3 is larger than or equal to the difference between the upper limit of a hydraulic press and the thickness of the upper cutting board 1 and the thickness of a finished product forged piece.

Example two

The embodiment provides a full-coverage forging method, which comprises the following steps:

step 1: the forging attachment is mounted on a forging device (for example, a hydraulic press) with the initial blank 4 interposed between the upper anvil 1 and the lower anvil 3;

step 2: a first pass of square drawing is carried out, a first pass target size is set according to the first pass reduction amount, the upper chopping board 1 is pressed down, so that the initial blank 4 reaches the first pass target size, and the blank is turned for 90 degrees;

and step 3: square drawing for the second pass, setting the target size of the second pass according to the reduction of the second pass, and reducing the upper chopping board 1 to ensure that the initial blank 4 after the first pass reaches the target size of the second pass and turns for 90 degrees;

and 4, step 4: carrying out multi-pass square drawing (for example, 4-8 passes), calculating the target size of each pass according to the reduction of each pass, pressing the upper chopping board 1, turning the upper chopping board 90 degrees after each time of square drawing, and carrying out next pass square drawing to obtain a square-drawn forged piece 2;

and 5: chamfering, chamfering and octagonal, rounding for 22.5 degrees, referring to fig. 3, drawing to the target diameter of the finished product forged piece, and obtaining the finished product forged piece.

Considering that the contact area of the initial blank 4 with the upper anvil 1 and the lower anvil 3 is small in the first pass and the second pass, the first pass reduction and the second pass reduction are large, the contact becomes large as the forging progresses, and the reduction after the third pass is reduced as compared with the first pass reduction and the second pass reduction. Illustratively, the first pass reduction is 30-35%, the second pass reduction is 35-40%, and the third pass reduction is 20-25%.

It is noted that the forging deformation spread of the initial blank 4 is significant, whereas the blank is controlled substantially square after the even-numbered forging passes, so that the reduction in the even-numbered passes is generally higher between adjacent passes than in the previous odd-numbered passes.

Illustratively, the diameter ratio of the side length of the forged piece 2 after the drawing in the step 4 to the finished forged piece is 0.9-0.95. Because the full-coverage type forging attachment is adopted, the transverse widening of the forge piece is large in the chamfering and rounding process, and even if the side length of the forge piece 2 after square drawing is smaller than the diameter of the finished forge piece, the required diameter of the finished forge piece can be obtained through the transverse widening, so that the rapid rounding can be realized, the limit deformation can be realized, and the forge piece compacting effect is improved. It should be noted that, in the prior art, because the chopping block has a lapping phenomenon in the chamfering and rounding process, a large transverse widening cannot be achieved, and once the rolling reduction is too large, the forge piece is folded, so that the side length of the forge piece 2 after being pulled by adopting the existing forging method must be larger than or equal to the diameter of the finished forge piece.

Specifically, the step 1 includes the steps of:

step 11: mounting the upper chopping block 1 at the output end of the hydraulic press, and lifting the upper chopping block 1 to the upper limit of the hydraulic press;

step 12: placing the lower chopping block 3 on a walking platform of a hydraulic press, and aligning the upper chopping block 1 and the lower chopping block 3;

step 13: the walking board is opened, the lower cutting board 3 and the upper cutting board 1 are staggered, the initial blank 4 is placed on the lower cutting board 3, and the axis of the initial blank 4 is superposed with the central line of the upper cutting board 1 or the lower cutting board 3 to avoid the occurrence of the unbalance loading phenomenon in the forging process;

step 14: the upper anvil 1 is realigned with the lower anvil 3 so that the initial blank 4 is placed between the upper anvil 1 and the lower anvil 3.

It should be noted that, since the forging attachment has a large contact area with the forging during forging and requires a high capacity for the forging device, the forging device may be selected according to the maximum deformation force of the initial blank 4, specifically, the maximum deformation force of the initial blank 4 is equal to the forging attachment area (length of the upper anvil 1 × width of the upper anvil 1 or length of the lower anvil 3 × width of the lower anvil 3) and the yield stress σ of the material of the initial blank 4 at the lowest forging temperature and strain rate of 0.01_sThe maximum working pressure of the forging apparatus is greater than or equal to the maximum deformation force of the initial blank 4.

The finished product forged piece manufactured by the forging attachment and the forging method of the embodiment is subjected to flaw detection, meanwhile, the finished product forged piece manufactured by the existing common attachment and the existing conventional forging method is subjected to flaw detection, and the flaw detection shows that the finished product forged piece manufactured by the forging attachment and the forging method of the embodiment has clear bottom wave, good surface quality and obviously improved core flaw detection quality, and the finished product forged piece manufactured by the existing common attachment and the conventional forging method has serious core defect wave, serious bottom wave attenuation and improper core flaw detection.

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 full-coverage forging accessory is characterized by comprising an upper chopping board and a lower chopping board which are oppositely arranged, wherein a blank is arranged between the upper chopping board and the lower chopping board;

the projection of the upper anvil and the lower anvil on the blank completely covers the blank.

2. The full mantle forging attachment of claim 1, wherein the full mantle forging attachment is adapted for forging of 20t or more billets.

3. The fully shrouded forging attachment of claim 1 wherein the length of the upper anvil and lower anvil is greater than or equal to the length of a forging after a forging compaction stroke.

4. The full coverage forging attachment of claim 1, wherein the width of the upper anvil and the lower anvil is greater than or equal to the product of the diameter and the coefficient of broadening of the starting blank.

5. The full mantle forging attachment of claim 1, wherein the determination of the thickness of the upper anvil plate comprises the steps of:

step a: determining an initial thickness;

6. The full mantle forging attachment of claim 1, wherein the thickness of the lower anvil plate is greater than or equal to the difference between the upper limit of the hydraulic press and the thickness of the upper anvil plate and the thickness of the finished forging.

7. A full-coverage forging method, characterized in that the full-coverage forging jig of claims 1 to 6 is used, and the forging method comprises the steps of:

step 1: mounting the forging attachment on a forging device, and placing an initial blank between an upper cutting board and a lower cutting board;

and 4, step 4: carrying out multi-pass square drawing, calculating the target size of each pass according to the reduction of each pass, pressing down the upper chopping board, turning over 90 degrees after each time of square drawing, and carrying out next pass square drawing to obtain a square-drawn forged piece;

and 5: and (5) chamfering, rounding, and drawing out to the target diameter of the finished product forged piece to obtain the finished product forged piece.

8. The full-coverage forging method as claimed in claim 7, wherein the diameter ratio of the side length of the forged piece after drawing in the step 4 to the finished forged piece is 0.9-0.95.

9. The full coverage forging method as recited in claim 7, wherein the step 1 comprises the steps of:

step 14: realigning the upper anvil and the lower anvil such that the initial blank is placed between the upper anvil and the lower anvil with the axis of the initial blank coinciding with the centerline of the upper anvil or the lower anvil.

10. The full-coverage forging method as claimed in claim 7, wherein the maximum deformation force of the initial blank is equal to the forging attachment area and the yield stress sigma of the initial blank material at the lowest forging temperature and strain rate of 0.01_sThe maximum working pressure of the forging apparatus is greater than or equal to the maximum deformation force of the initial blank.