RU2550067C1 - A die with horizontally parting female dies for cross-piece forgings - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to metal forming and may be used in forging of cross-pieces. Male die is arranged at top mould top plate. Bottom female die is arranged at bottom plate with crossbar. Top and bottom female dies have joint surface with equal central and peripheral sections. Top female die is coupled with crossbar by ties and arranged to displace relative to bottom female die to make a closed die chamber. Ejector is arranged in bottom female die to rest via spring-loaded pusher on said crossbar. Peripheral sections of parting surface of said female dies are inclined to side surface thereof. Said ties are arranged in through straight slots made at opposite side walls of female dies parallel with the mould mirror axis. This results in tight camping of female dies over forged-piece contour owing to plastic deformation of macro irregularities and waviness unavoidable after finishing of female die contact surfaces.

EFFECT: accurate alignment of female dies.

3 dwg

Description

The invention relates to the field of metal forming and can be used for stamping forgings of complex shape such as crosses.

Known stamp with a horizontal connector matrix for stamping forgings such as crosses, containing a top plate with a punch and an elastic element mounted on it, made in the form of spring blocks of different stiffness, an intermediate and lower plate, on which are mounted the upper and lower matrices, forming a closed die cavity by mating the surfaces of the connector, as well as an ejector resting on the beam, located in the lower matrix. Clamping the matrices with an elastic element made in the form of spring blocks of various stiffness allows reliable compression of the matrices and thereby improving the quality of forgings (Sokolov N.L. Hot stamping by extrusion of steel parts / NL Sokolov. - M.: Mechanical Engineering, 1967, p. .141-143, Fig. 96).

The main disadvantage of the known die with a horizontal die connector for stamping forgings such as crosses is the low quality of the obtained 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 clamping force matrices are not consistent with the disclosing forces perceived by the matrices from the side of the deformable metal during the stamping process.

Known stamp with a horizontal connector matrix for stamping forgings such as cross pieces, containing an upper plate with a punch mounted on it, a lower plate on which a lower matrix is mounted, a crosshead located in the lower plate, an upper matrix connected to the traverse by rods, having the same with the lower matrix central and peripheral portions of the surfaces of the connector and the ability to move relative to the lower matrix with the formation of the mating portions of the surfaces of the connector of both matrices of the closed die cavity, as well as an ejector arranged at the bottom of the matrix and supported through a spring loaded pusher yoke. The matrix clamping, carried out by means of the formation of forgings, removed from the ejector during stamping and applying it to the upper die in the direction of the punch action, allows you to create a self-regulating closed power system that provides reliable compression of the matrices (patent RU 2399456, IPC, B21K 1/76). This technical solution is the closest in the set of essential features and is selected as a prototype.

The main disadvantage of the described stamp with a horizontal connector matrix for stamping forgings such as crosses is that the compression matrix is carried out over the entire area of their Central and peripheral sections of the surfaces of the connector. However, in the presence of macro-irregularities and undulations that are unavoidable after grinding of the connector surfaces (RI Gzhirov, Designer's Quick Reference / RI Gzhirov. - L.: Mechanical Engineering, Leningrad Branch, 1983, p. 124, 158, 160, 164), clamp matrices over the entire area of their central and peripheral sections of the surfaces of the connector makes it impossible to tightly match the matrices along the entire contour of the forging in the plane of the connector matrix. As a result of the local exit of the stamped metal into the die connector with the formation of a burr, the quality of the forgings decreases.

The basis of the invention is the task of improving the quality of forgings such as crosses.

To solve the problem, in a stamp with a horizontal die connector for stamping forgings, such as cross pieces, containing an upper plate with a punch mounted on it, a lower plate on which a lower matrix is mounted, a crosshead located in the lower plate, an upper matrix connected to the traverse with rods, having the central and peripheral portions of the connector surfaces that are equally large with the lower matrix and the ability to move relative to the lower matrix with the formation of the mating portions of the connector surfaces of both matrices are closed of the die cavity, as well as an ejector located in the lower matrix and supported through the spring-loaded pusher on the beam, according to the invention, the peripheral portions of the surfaces of the connector of the lower and upper matrices are made with slopes in the matrix body to the sides of their side surfaces, and the area of the mating central sections of the surfaces of the connector is lower and upper matrices are determined from the relation:

$$F_c=R_s/{\sigma }_{\mathrm{at}},(\mathrm{one})$$

where F _c is the area of the mating central portion of the surface of the matrix connector;

P _s - clamping force of the matrices;

σ _y is the elastic limit of the matrix material.

In addition, in the proposed technical solution, the rods are placed in straight through grooves made in the opposite side walls of the matrices parallel to the axis of symmetry of the stamp.

Clamping the dies in the central sections that are directly adjacent to the forging contour in the plane of the die connector allows the clamping force to be concentrated near the forging contour. As a result of plastic deformation of macro-irregularities and waviness in these surface areas, tight mating of surfaces is provided near the forging contour in the plane of the connector, which excludes the exit of the stamped metal into the burr. And the placement of rods connecting the upper matrix with the traverse in the through grooves made in the opposite side walls of the matrices parallel to the axis of symmetry of the stamp, allows for more accurate alignment of the matrices and further improve the quality of forgings.

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

A stamp with a horizontal die connector for stamping cross-type forgings comprises a top plate (not shown in the drawing) with a punch 1 installed on it, a bottom plate 2 on which a lower die 3 is mounted. A cross beam 5 is placed under the lower die 3 in the groove 4 of the lower plate 2 rigidly connected by rods 6 and 7 to the top plate. A pusher 8 is installed on the traverse 5, on the sides of which there are bevels 9 and 10, and a support spring 11 is installed inside the pusher 8 (Fig. 1).

The upper matrix 14 connected to the traverse 5 by rods 12 and 13 has the central 15 and 16 and peripheral 17 and 18 sections of the surfaces of the connector 19 and 20 respectively of the matrices 14 and 3 with the lower matrix 3 and the possibility of creating a closed cavity 21 of the stamp 22 together with the lower matrix 3 (figure 2) by pairing the Central sections 15 and 16 of the surfaces of the connector 19 and 20 of the matrices 14 and 3. In the lower matrix 3 there is a pusher 23, based on the pusher 8 in the initial position of the stamp 22 (figure 1) and at the time of removal of the forging 24 from the lower matrix 3 (figure 2 and 3) and the cams 25 and 26 rods 12 and 13 at the time of receipt of the forgings 24 (figure 2). On the ejector 23 in the upper matrix 14 in the initial position of the stamp 22, a workpiece 27 is installed (Fig. 1).

The peripheral sections 17 and 18 of the surfaces of the connector 19 and 20, respectively, of the matrices 14 and 3 are made with slopes 28 and 29, and the central sections 15 and 16 adjacent to the contour 30 of the forging 24 are aligned with the plane of the connector 31 of the matrices 14 and 3 (Fig. 2) .

In the opposite side walls 32 and 33 of the matrix 3, 34 and 35 of the matrix 14, straight through grooves 36 and 37 are made parallel to the axis of symmetry 38 of the stamp 22 (figure 2).

A stamp with a horizontal connector matrix for stamping forgings such as crosses works as follows.

In the initial position of the stamp 22, the workpiece 27 heated to the forging temperature is installed in the matrix 14 on the ejector 23. Then the upper plate (not shown in the drawing) and the associated punch 1 and the crosshead 5 are moved down. In this case, the cams 25 and 26 of the rods 12 and 13 slide along the bevels 9 and 10 of the pusher 8 and come closer, and the support spring 11, unclenching, holds the ejector 23 in the upper position (figure 1). Under the influence of its own weight, the upper matrix 14, falling down, closes with the lower matrix 3, creating a closed cavity 21 of the stamp 22, and the cams 25 and 26 of the rods 12 and 13 go under the ejector 23 (Fig.2).

Further, by means of the punch 1, a forging 24 is formed. From the moment the forging 24 is formed, part of the stamping force is transmitted to the ejector 23, then to the cams 25 and 26 and by means of the rods 12 and 13 to the upper die 14. In this case, the rods 12 and 13 are placed in the grooves 36 and 37 with a minimum gap, ensure accurate alignment of both matrices 3 and 14, and clamping the matrices 3 and 14 in the central sections 15 and 16 adjacent to the contour 30 of the forging 24 provides tight coupling of the surfaces of the connector 19 and 20 of the matrices 14 and 3 near the circuit 30 forgings 24 (figure 2).

After the formation of forgings 24, the upper plate with the punch 1 and the traverse 5 moves up. By means of bevels 9 and 10 of the pusher 8, the cams 25 and 26 of the rods 12 and 13 are opened and out of contact with the ejector 23, which, moving upward under the action of the pusher 8, removes the forging 24 from the lower matrix 3. At this point, the crosshead 5, acting on the cams 25 and 26, by means of rods 12 and 13 raises the upper matrix 14, forming a gap between the matrices 3 and 14, smaller than the height of the workpiece 27 (figure 3).

To hold the forging 24 in the lower die 3 after stamping, the stamping slopes in this die are smaller than in the upper die 14.

Example. A pilot batch of 24 forgings from 18X2H4BA steel is stamped. The diameter of the hub D _c = 42 mm; forging height 24 H _to = 26 mm; appendix diameter d ₀ = 21 mm; process length l ₀ = 24 mm; workpiece diameter 27 D ₃ = 40 mm; workpiece height 27 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 24 type of cross according to the formula

where r ₁ is the radius of curvature in the upper matrix 14, r ₁ = 1 mm;

r ₂ is the radius of curvature in the lower matrix 3, 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 24 in plan, mm ² .

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

Specific force p = 288.4 MPa.

To clarify, the value of the specific force p during the deformation of 18X2H4BA steel, depending on the degree of deformation and temperature, is selected according to the schedule in Fig. 5.25 (A. Atroshenko, Hot stamping of difficult to deform materials / A. P. Atroshenko, V. I. Fedorov. - L. : Engineering, 1979, p. 174).

The degree of deformation ε is found by the formula

$$\epsilon =\ln \frac{F}{f},(3)$$

where F is the cross-sectional area of the workpiece 27, mm ² ;

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

; $$F=\frac{\pi }{\mathrm{four}}{\mathrm{<figure-callout\; id="3"\; label="D"\; filenames="00000016.png"\; state="\{\{state\}\}">D</figure-callout>}}_3^2=\frac{\pi }{\mathrm{four}}\ast {40}^2=1256{\text{<figure-callout id="2" label="mm" filenames="00000016.png" state="{{state}}">mm</figure-callout>}}^{\text{2}}$$

;

; $$f=\frac{\pi }{\mathrm{four}}{d}_0^2=\frac{\pi }{\mathrm{four}}\ast {21}^2=346.2{\text{<figure-callout id="2" label="mm" filenames="00000016.png" state="{{state}}">mm</figure-callout>}}^{\text{2}}$$

;

. $$\epsilon =\ln \frac{1256}{346.2}=1.28$$

.

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

Then the stamping force

P = p Fn = 360 * 3401 = 1224360 H = 1224 kH.

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

2. Determine the maximum clamping force of the matrices 14 and 3 by the force attributable to the ejector 23 at the end of stamping:

$$R_s=R_{\mathrm{at}}=p\cdot f_{\mathrm{at}},(\mathrm{four})$$

where P _s - clamping force of the matrices 14 and 3, kN;

P _in - force on the ejector 23, kN.

f _in - the area of the end face of the ejector 23, equal to the area of the end face of the hub forgings 24, mm ² .

$$P_s=360\cdot \frac{\pi }{\mathrm{four}}\cdot {42}^2=500\mathrm{to}H,$$

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 area of the conjugate surface of the matrices 14 and 3 according to the formula (1).

As the material of the matrices 14 and 3 choose steel grade 4X4VMFS; the elastic limit of steel is taken equal to the yield strength of this steel, i.e. σ _y ≈σ _0.2 = 1080 MPa at a heating temperature of matrices 14 and 3 during stamping to 600 ° C (see the book Geller Yu.A. Tool steel. / Yu.A. Geller. - M .: Metallurgy, 1983 , p. 439).

F _c = P _s / σ _y = (0.5 / 1080) · 10 ⁶ , mm ² = 463 mm ² .

Since the presence of macro-irregularities and waviness of the surfaces of the matrices 14 and 3 after grinding reduce the actual contact area by 5-10 times (see the book RI Gzhirov, Designer's Quick Reference / RI Gzhirov. - L .: Engineering, Leningrad Branch, 1983 , p.160), then the area of the actual clamping of the matrices 14 and 3 increases by 8 times. Then

F _sf = 8 · F _s = 8 · 463 = 2904 mm ² .

The shape of the clamping area of the matrices 14 and 3 is taken in the form of a strip of the central portion 15 or 16 of the surfaces of the connector 19 or 20 adjacent to the contour of the forging 24 in the plane of the connector 31 of the matrices 14 and 3, i.e.

$$F_{\mathrm{from}f}={\mathrm{at}}_{P\mathrm{about}l}\cdot {\ell }_{PeR},(5)$$

where in the _floor is the width of the strip of the central section 15 or 16 of the surfaces of the connector 19 and 20 of the matrices 14 and 3, mm;

ℓ _per - the length of the perimeter of the contour of the forgings 24 in the plane of the connector 31 of the matrix 14 and 3, equal to 342 mm

From here

to the _floor = F _sf / ℓ _per = 2904/342 = 8.5 mm.

Take in the _floor = 10 mm.

4. Determine the cross-sectional area of the rods 12 and 13, transmitting force to the upper matrix 14

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

where P _t is the force per one thrust.

Operating stress σ _p in traction

$${\sigma }_R=P_t/S_t,(6)$$

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

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

where σ _m is the yield strength of the traction material.

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

Since the width In the groove 4 in the lower plate of the stamp 22 should be greater than the diameter of the ejector 23, equal to the diameter of the hub D _{c of the} forging 24 by the amount of clearance, then

B = D _c + Z,

where Z = 3 mm is the gap between the lateral surface of the ejector 23 and the walls of the groove 4;

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.

5. 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 24 and the surface of the connector 19 of the upper matrix 14, necessary for the convenience of removing the forgings 24;

h _VM = 26 + 10 = 36 mm,

which is half the height of the workpiece 27, equal to H ₃ = 64 mm, placed at the end of the ejector 23 in the upper matrix 14.

6. Calculate the stroke of the ejector 23 (h _in ) equal to

$$h_{\mathrm{at}}=\left(H_{\mathrm{from}}/2\right)+Z_{\mathrm{at}},\text{(7)}$$

where Z _in = 4 mm is the accepted gap between the support of the ejector 23 and the lower surface of the lower matrix 3;

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

Forgings 24 obtained by the proposed method had no burrs on the plane of the connector 31 of the matrices 14 and 3.

Thus, the proposed invention significantly improves the quality of forgings such as crosses, as it provides tight clamping of the matrices along the contour of the forgings as a result of plastic deformation of macro-irregularities and waviness that are inevitable after grinding of the contact surfaces of the matrices, and the use of tie rods of the matrices as guides provides more accurate combination of matrices and further improves the quality of forgings.

Claims (1)

A stamp with a horizontal die connector for stamping cross-type forgings, comprising a top plate with a punch installed on it, a bottom plate on which the lower die is mounted, a cross-arm placed in the lower plate, an upper die that is connected to the cross-arm by means of rods, is made with a central and peripheral portions of the surface of the connector equal to the Central and peripheral portions of the surface of the connector of the lower matrix, and has the ability to move relative to the lower matrix with the formation of mating central parts of the surfaces of the connector of both matrices of the closed die cavity, as well as an ejector placed in the lower matrix with support through a spring-loaded pusher on the beam, characterized in that the peripheral parts of the surfaces of the connector of the lower and upper matrices are made with slopes in the matrix body towards their side surfaces, the area of the mating Central sections of the surfaces of the connector of the lower and upper matrices F _{c is} determined from the ratio:
F _c = P _s / σ _y
where P _s - the clamping force of the lower and upper matrices;
σ _y - the elastic limit of the material of the lower and upper matrices,
and the rods are placed in straight through grooves made in the opposite side walls of the lower and upper matrices parallel to the axis of symmetry of the stamp.

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