RU2399456C1 - Method for stamping of forged pieces of crosspiece type in stamp with horizontal connector of matrices - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention relates to the field of metal plastic working and may be used to make stamp forged pieces of complex configuration of crosspiece type. Stock is heated up to forging temperature. Then it is placed on end of pusher in upper matrix. Upper matrix is installed on traction rods at the distance from lower matrix mounted on lower plate of stamp, smaller than stock height. Further matrices are pressed by means of forged piece forming effort. This effort is taken off pusher in process of stamping and is applied to upper matrix in direction of puncheon action.

EFFECT: invention provides for improved quality of forged pieces of crosspiece type.

1 ex, 3 dwg

Description

The invention relates to the processing of metals by pressure and can be used for stamping forgings of complex configuration such as crosses.

There is a method of stamping forgings such as crosses in a die with a horizontal die connector, which consists in heating the workpiece, placing it on the end face of the lower punch in the lower matrix, closing the upper and lower dies and forming a forging by extruding the metal with punches simultaneously from both dies, clamping them at the moment contact of the upper punch with the workpiece. In this case, the clamping of the matrices is carried out by moving the upper punch and the upper plate rigidly connected with it and exposing it through the elastic element to the upper matrix (patent RU 2165329, IPC ⁷ B21K 1/00).

Simultaneous extrusion of metal from both matrices allows eliminating internal defects in the forging, however, the use of an elastic element for clamping the matrices requires additional press force and does not provide for their tight compression throughout the process of forming the forging, since the clamping force of the matrices is not consistent with the opening forces perceived by the matrices from the side of the deformable metal, which leads to the formation of a burr in the plane of the connector and intensive wear of the edges of the streams of the matrices. As a result, the quality of forgings obtained by the above method and the durability of the stamp implementing this method are reduced (Atroshenko A.P. Hot stamping of difficult to deform materials / A.P. Atroshenko, V.I. Fedorov. - L .: Engineering, 1979 , P. 174).

A known method of stamping forgings such as crosses in a stamp with a horizontal die connector, which consists in heating the workpiece, placing it on the end of the ejector in the upper matrix mounted in the intermediate plate, which is mounted on rods at a distance from the lower die mounted on the lower plate of the stamp, less height blanks. Then the matrices are closed and the one-junction forgings are formed by a punch, during which the matrices are clamped by an elastic element, acting on this elastic element made of six spring blocks, each of which is made of one spiral and a set of Belleville springs that come into operation by the end of the working stroke when the opening forces perceived by the matrices from the side of the deformable metal reach their maximum values with the upper die plate. Thus, a set of springs of different stiffness allows more reliable compression of the matrix, thereby improving the quality of forgings (Sokolov NL Hot stamping by extrusion of steel parts / NL Sokolov. - M.: Mechanical Engineering, 1967, S.141-143, fig. 69). This technical solution is the closest in the set of essential features and is selected as a prototype.

The main disadvantage of the described method of stamping forgings such as crosses in a die with a horizontal die connector is the reduced quality of the resulting forgings due to the formation of a burr in the plane of the die die, since the use of an elastic element to clamp the dies does not provide tight compression throughout the forging process, since the force the clamping of the matrices is not consistent with the disclosing forces perceived by the matrices from the side of the deformable metal during the stamping process. In addition, the stamping process is highly energy-intensive, since an additional press force is expended to compress the elastic element by acting on the upper die plate. (Atroshenko A.P. Hot stamping of difficult-to-deform materials / A.P. Atroshenko, V.I. Fedorov. - L .: Mashinostroenie, 1979, P.174).

The basis of the invention is the task of improving the quality of forgings such as cross pieces obtained by the proposed method.

To solve the problem in a method of stamping forgings such as crosses in a die with a horizontal die connector, which consists in heating the workpiece, placing it on the end of the ejector in the upper die mounted on rods at a distance from the lower die mounted on the lower die plate, less than the height of the die, clamping of matrices and single-junction formation of forgings by a punch during which the matrix is clamped; according to the invention, the matrix is clamped by the forging formation force; a second ejector in the stamping process, with its application to the top of the matrix in the direction of action of the punch.

Using the forging forming force for clamping the dies allows you to create a self-regulating closed power system that provides reliable clamping of the dies, since the clamping force of the dies through the forging forming force is directly related to the opening forces perceived by the matrices during the entire deformation process, which eliminates the formation of burrs in the matrix connector. As a result, the quality of forgings is improved. In addition, the stability of the stamp increases, the energy intensity of the stamping process, which does not require additional compression force of the elastic element to clamp the dies, decreases.

The proposed invention is illustrated by drawings, where figure 1 shows the initial position of the stamp, figure 2 - the position of the stamp at the time of stamping, figure 3 - position of the stamp at the time of removal of the forging.

A method of stamping forgings such as crosses in a stamp with a horizontal die connector is implemented as follows.

The workpiece 1 is heated to forging temperature and placed on the end 2 of the ejector 3 in the upper matrix 4 mounted on rods 5 at a distance from the lower matrix 6, less than the height of the workpiece 1 (figure 1). Next, the matrices are closed, for which the upper plate (not shown) of the stamp 7 and the crosshead 8 with the pusher 9 mounted on it, containing the support spring 10, are moved downward by means of the rods 11. While expanding the supporting spring 10 hold the ejector 3, mounted on the beam 12, in the upper position. At the same time, the cams 13 of the rods 5, which are in the initial position of the stamp 7 in the diluted state, are reduced by moving them along the bevels 14 of the pusher 9, and the upper matrix 4 is lowered along the guide columns 15 by its own weight until it engages with the lower matrix 6 mounted on the lower plate 16 of stamp 7. In the plate 16, a groove 17 is made, in which the ejector 3, the beam 12, the pusher 9 and the cams 13 of the rods 5 are placed (Fig. 2).

Then, one-junction formation of the forgings 18 is carried out with a punch 19 fixed on the upper plate, during which the matrices 4 and 6 are clamped. For this, the forgings forming force 18 is removed during stamping from the ejector 3, which is supported by the beam 12 on the supporting platforms 20 of the cams 13 of the rods 5 , and apply using rods 5 to the upper matrix 4 in the direction of action of the punch 19 (figure 2).

After the forging 18 is formed, the upper plate with the punch 19 is moved up. While the rods 11 raise the yoke 8 and by means of the pusher 9, the cams 13 of the rods 5 are spread. Then the upper matrix 4 is lifted along the guide columns 15 by the rods 5, the cams 13 of which are supported in the yoke 8 (Fig. 3).

To hold the forgings 18 in the lower die 6 after stamping, the stamping slopes in the brook 21 of this die 6 are smaller than the corresponding slopes in the brook 22 of the upper die 4. In addition, the height of the hub 23 of the forgings 18 formed in the lower die 6 is greater than the corresponding height of the hub 24 of the forgings 18, formed in the upper matrix 4, due to the increment of its size as a result of compensation for excess metal during stamping during elastic deformation of the rods 5.

With further movement of the pusher 9 up, the support spring 10, as a result of compression, is buried in the socket 25 of the pusher 9, and the last, acting through the beam 12 on the ejector 3, pushes the forging 18 from the stream 21 of the lower matrix 6 (Fig. 3). After removing the forging 18, the stamping process is repeated.

Example. A pilot batch of forgings from a 18Kh2N4VA steel cross is stamped. The diameter of the hub D _c = 42 mm; forging height N _to = 26 mm; appendix diameter d ₀ = 21 mm; process length l ₀ = 24 mm; workpiece diameter D ₃ = 40 mm; workpiece height H ₃ = 64 mm. Stamping temperature T = 1100 ° C.

The calculation of the parameters of the stamping process is carried out in the following order.

1. Determine the force of the closed stamping forgings type crosses according to the formula

;

;

where r ₁ is the radius of curvature of the forgings near the punch, r ₁ = 1 mm;

r ₂ is the radius of curvature of the bottom corner of the matrix, r ₂ = 1 mm;

d is the diameter of the forging, mm;

σ _in - the tensile strength of steel at the temperature of stamping;

σ _in = 56 MPa for steel 18X2H4 VA at a temperature of 1000 ° C;

F _n - the projection area of the forgings in terms of mm ² .

(Forging and stamping: a reference book: in 4 vol. T.2. Hot stamping / Ed. Advice E.I. Semenov [et al.] - M.: Mashinostroenie, 1986, S.202).

Specific force p = 288.4 MPa.

In order to clarify the magnitude of the specific force (p) during the deformation of 18Kh2N4VA steel, depending on the degree of deformation and temperature, is selected according to the graph in Fig. 5.25 (A.P. Atroshenko Hot stamping of difficultly deformed materials / A.P. Atroshenko, V.I. Fedorov. - L .: Engineering, 1979, p. 174).

The degree of deformation ε is found by the formula

,

,

where F is the cross-sectional area of the workpiece, mm ² ;

f is the cross-sectional area of the process, mm ² ;

According to the schedule, p = 360 MPa, which exceeds the specific force obtained by calculation. Choose a larger value equal to p = 360 MPa.

Then the stamping force

P = pFn = 3603401 = 1224360 H = 1224 KN.

Select hot stamping press model KB 0034B with an effort of 2500 KN.

2. Determine the maximum clamping force of the matrices by the force attributable to the ejector at the time of stamping:

P _sf = P _in = p · f _in

where R _szh - the clamping force of the matrices, KN.

P _in - force on the ejector, KN.

f _in - the area of the end face of the ejector equal to the area of the end face of the hub forgings, mm ² .

что не превышает 50% усилия штамповки Р=1224 КН (Соколов Н.Л. Горячая штамповка выдавливанием стальных деталей / Н.Л.Соколов. - М.: Машиностроение, 1967, С.62).

which does not exceed 50% of the stamping force P = 1224 KN (Sokolov NL Hot stamping by extrusion of steel parts / NL Sokolov. - M .: Mechanical Engineering, 1967, P.62).

3. Determine the cross-sectional area of the rods that transmit force to the upper matrix

P _t = P _in / 2 = 500/2 = 250 kN,

where R _t is the force per one thrust.

The operating stress σ _p in traction is

σ _p = P _T / S _T ,

where S _T = a · in - the cross-sectional area of the thrust. Here a is the thickness of the thrust section, mm; in - the width of the thrust section, mm ² .

To exclude residual deformation, take σ _p = 0,5σ _t ,

where σ _t - yield strength of the traction material.

Steel 30KhGSA, σ _T = 850 MPa, are taken as the traction material.

Since the width (B) of the groove in the bottom plate of the stamp must be greater than the diameter of the ejector equal to the diameter of the hub of the forging (D _c ) by the amount of clearance, then

B = D _c + Z,

where Z = 3 mm is the gap between the lateral surface of the ejector and the walls of the groove;

B = 42 + 3 = 45 mm.

Take the width of the thrust section in = 40 mm, then the thickness of the thrust section will be equal to

Take a = 20 mm.

3. Calculate the course of the upper matrix

h _vm = H _s + Z _m ,

where Z _m = 10 mm is the accepted gap between the upper end face of the forgings and the contact surface of the upper matrix, necessary for the convenience of removing the forgings;

h _VM = 26 + 10 = 36 mm,

which is half the height of the workpiece, equal to H ₃ = 64 mm, placed at the end of the ejector in the upper matrix.

5. Calculate the stroke of the ejector (h _in ) equal to

h _in = (H _c / 2) + Z _in ,

where Z _in = 4 mm is the accepted gap between the beam on which the ejector is mounted and the lower surface of the lower matrix;

h _B = (26/2) + 4 = 17 mm.

A cylindrical blank 1 with a diameter of 40 mm, a height of 64 mm is heated to a temperature of 1100 ° C and placed on the end face 2 of the ejector 3 in the upper matrix 4. mounted on rods 5 at a distance from the lower matrix 6, equal to 36 mm. Next, they start the press and close the matrices 4 and 6 as a result of moving down the crosshead 8 with the pusher 9 fixed on it. At the same time, moving the cams 13 of the rods 5 along the bevels 14 of the pusher 9, the cams 13 are reduced, and the upper matrix 4 is lowered along the guide columns 15, close to the lower matrix 6. Then, one-junction formation of the forging 18 is carried out by the punch 19, during which a force of up to 500 kN is removed from the ejector 3 and applied to the upper matrix 4 in the direction of action of the punch 19.

The use of the forging forming force for clamping the dies allows you to create a self-regulating closed power system that provides reliable clamping of the dies, since the clamping force of the dies through the forging forming force is directly related to the opening forces perceived by the matrices during the entire deformation process.

After the forging 18 is formed, the upper plate with the punch 19 is moved upward, by means of the pusher 9, the cams 13 of the rods 5 are bred and the upper matrix 4 is lifted by 23 mm. In this case, the forging 18 remains in the stream 21 of the lower die 6, since the stamping slopes in this stream are 1 °, and in the stream 22 of the upper die 4 they are equal to 3 °. In addition, the height of the hub 23 of the forgings 18 formed in the lower die 6 is 3 mm, and the corresponding height of the hub 24 formed in the upper die is 2 mm.

With the further movement of the pusher 9 upward, acting through the beam 12 on the ejector 3, the forgings 18 are pushed out of the stream 21 of the lower matrix 6 by half the forging height equal to 13 mm, which provides a gap between the end face of the forgings 18 and the contact surface of the upper matrix at least 10 mm . At the same time, the upper matrix 4, the stroke of which will be 36 mm, is raised by the same amount by means of rods 5.

The obtained forgings had a smooth surface without traces of burrs along the plane of the matrix connector.

Thus, the proposed invention allows to improve the quality of forgings such as crosses obtained during the implementation of the method, to increase the durability of the stamp and reduce the energy intensity of the stamping process.

Claims (1)

A method of stamping forgings such as crosses in a die with a horizontal die connector, including heating the workpiece, placing it on the end of the ejector in the upper die mounted on rods at a distance from the lower die mounted on the lower die plate, less than the height of the workpiece, closing the dies and one-junction forging a punch during which the die is clamped, characterized in that the die is clamped by the forging force removed from the ejector during stamping its application to the top of the matrix in the direction of action of the punch.

Images