RU2538063C1 - Forging hammer stock - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: forging hammer stock is provided with a blind axial stepped hole. Steps of the hole are located with reduction of their diameter from the stock end opposite to the place of its embedment into a hammer head. The result is achieved due to redistribution of stresses in different sections of the stock at impact action.

EFFECT: reduction of loads occurring in a stock embedment place, which allows reducing costs caused by replacement of stocks and failure of equipment during its replacement period.

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Description

The invention relates to the field of engineering and can be used in industrial production.

The objective of the invention is the creation of a forging hammer rod, which provides a technical result, consisting in increasing the reliability of the rod and increasing the service life by reducing mechanical stresses that occur during operation of the forging hammer.

Known forging hammer rods having a solid cross section according to GOST 9752-75.

From the analogues of the prior art, the rod of the forging hammer M1345 can be taken as a prototype (see GOST 9752-75). The existing stem design is shown in figure 1.

A disadvantage of the known design is the lack of reliability and durability of the rod in the place of its incorporation into the woman.

The technical result of the invention is to reduce the stresses arising at the place of stemming into the shaft, and is aimed at increasing the reliability of the rods, which allows to increase their service life and, thereby, reduce material losses from replacing the rods and from equipment downtime during their replacement.

The specified technical result in the invention is achieved by the fact that, as a new rod design, a rod with a blind axial stepped hole is used, the steps of which are located with decreasing diameter from one end opposite to the place where the rod is sealed in the hammer head.

The invention is illustrated by drawings, where figure 2 presents the proposed design of the rod having a blind axial stepped hole, the steps of which are located with a decrease in their diameter from one end opposite to the location of the rod in the hammer hammer;

figure 3 - schematic design diagram of the hammer, allowing for variant calculations in the case of the existing and proposed design of the rod, which shows 1-19 - system nodes, 20 - piston, 21 - rod, 22 - woman, 23 - top striker, 24 - billet, 25 - lower hammer, 26 - pillow, 27 - shabot, where sections 7-8, 12-13, 14-15 model joints, nodes 17, 18, 19 model an elastic base;

figure 4 - graphs of stresses σ (t) and the amplitude-phase-frequency characteristics (AFC) of the efforts at the site of embedment of the rod in the headstock for a workpiece made of steel 45 and the impact velocity V = 4 m / s;

figure 5 - distribution of the maximum stresses σ _max in the falling parts of the hammer upon impact with a speed of V = 3 m / s with a workpiece of size ⌀180 × 465 mm at time t = 0.01 s, where the solid line shows the stresses arising from the material billets - steel 45, dotted - with the material of the billet - aluminum alloy AK6;

6 - distribution of the maximum stresses in the falling parts of the hammer upon impact at a speed of V = 3 m / s with a workpiece of size ⌀180 × 465 mm at time t = 0.01, where the solid line is a curve, in the case of a known rod design, dashed line - curve, in the case of the proposed rod design;

Fig.7 is a comparison of theoretical and experimental amplitudes of stresses σ at the place of embedment of the rod into the woman in the case of different workpieces and impact speeds (a - steel 45, V = 4 m / s; b - titanium alloy OT4, V = 6 m / s; c - aluminum alloy AK6, V = 6 m / s), where the solid line is the experimental curve, the dashed line is the theoretical curve.

Stress reduction is achieved due to the redistribution of stresses during impact in various sections of the rod.

The strength of the parts of the hammer, the quality indicators of this machine depend on the strength of the forging resistance to deformation. Each hammer has a limiting forging, in which the durability of the weakest link (rod) is unsatisfactory. The rod of constant cross section is very far from an equal strength state, since it works under conditions of high shock loads, experiencing stress from longitudinal forces during impact. Two unfavorable factors act simultaneously in the place of stemming the rod into the woman: the maximum dynamic stress arises and the highest stress concentration takes place. As a result, the overwhelming number of breakdowns of such rods occurs in the same section - in the seal.

Thus, in the study of the reliability and durability of parts and components of the hammer, it becomes necessary to determine the current loads.

Consider, for example, an air-forged hammer forging arch type M1345 model (figure 3).

To perform calculations of the stress-strain state, as well as the calculation and design of a device for measuring the speed of the falling parts of the hammer, it is necessary to obtain the maximum speed value. It can be determined by the formula for kinetic energy

, $$K=\frac{m\cdot {\mathrm{<figure-callout\; id="2"\; label="V"\; filenames="00000028.png,00000029.png"\; state="\{\{state\}\}">V</figure-callout>}}^2}{2}$$

,

where m is the mass of the falling parts of the hammer, kg;

V is the initial impact velocity, m / s;

K - kinetic energy, J.

For the hammer of model M1345, the mass of the falling parts is m = 3150 kg, K = 80 kJ. Then the maximum speed will be equal

. $$V_{\max }=\sqrt{\frac{2\cdot K}{m}}=7,\mathrm{one}\frac{m}{\mathrm{from}}$$

.

It is proved that the dynamic calculation of the falling parts of the forging hammer without taking into account the deformation of the forging is completely unacceptable [Scheglov, V.F. Perfection of forging equipment of shock action / V.F. Shcheglov. - M.: Mechanical Engineering, 1968. - 222 p., Seidenberg, G.Ya. Issues of the dynamics of high-speed stamping hammers: abstract of a thesis of ... Dr. tech. sciences / G.Ya. Seidenberg. - M, 1970, - 31 s]. The forging is modeled as a Maxwell viscoelastic body. The lining under the Shabbat, consisting of oak beams, is modeled by an elastic base with concentrated stiffness c in the corresponding nodes of the system. Since the connection of the upper striker with a woman, the lower striker with a pillow and pillow with a shabot is carried out by a curly dovetail groove, the contact interaction of such joints can be modeled by a spring. The methodology for calculating contact deformations of joints, taking into account real conditions, was borrowed from [Levina, Z.M. Contact rigidity of machines / Z.M. Levina, D.N. Reshetov. - M.: Mechanical Engineering, 1971. - 267 p.].

Consider the frequency method for the dynamic calculation of unsteady oscillations of a forging hammer during impact interaction with a workpiece. The proposed methodology uses a modification of the finite element method (FEM) based on the exact integration of the differential equation for the finite element [Sankin, Yu.N. Dynamic characteristics of viscoelastic systems with distributed parameters / Yu.N. Sankin. - Saratov: Publishing house of Sarat. Univ., 1977. - 312 p.] and allows one to calculate the longitudinal and transverse vibrations of rods of stepwise variable cross section with or without energy dissipation in collisions with a hard obstacle [Sankin, Yu.N. Longitudinal vibrations of elastic rods of stepwise variable cross section upon impact with a rigid obstacle / Yu.N. Sankin, N.A. Yuganova // Applied Mathematics and Mechanics. - M .: Publishing House "Science", 2001. - Volume 65. Issue 3. - S. 444-450].

The proposed approach is valid for rods of unlimited length, therefore, the division into sections of the hammer can be carried out in any sections, but it is most advisable where the physical or geometric characteristics of the object change. When drawing up the calculation scheme of the hammer, it was believed that longitudinal oscillations occur in the stock, woman, strikers, pillow and upper part of the Shabot, and transverse at the base of the Shabot.

Thus, the design scheme of the forging hammer (figure 3) will consist of 19 nodes. Sections 7-8, 12-13, and 14-15 model joints. Knots 17, 18 and 19 have an elastic base, replacing the influence of the lining of oak beams. In sections between the nodes 1 and 18, longitudinal vibrations take place, and in sections 17-18 and 18-19 there are transverse vibrations. At the final stage of the impact, the upper striker is considered to have joined the workpiece (figure 3).

The proposed calculation scheme corresponds to the following system of resolving equations for constructing amplitude-phase-frequency characteristics (AFC) of displacements:

(S _1,2 -mω ² ) W ₁ -T _1,2 W ₂ = -T _1,2 [u ₂ ];

-T _1,2 W ₁ + (S _1,2 + S _2,3 ) W ₂ -T _2,3 W ₃ = -T _1,2 [u ₁ ] -T _2,3 [u ₃ ];

-T _2.3 W ₂ + (S _2.3 + S _3.4 ) W ₃ -T _3.4 W ₄ = -T _2.3 [u ₂ ] -T _3.4 [u ₄ ];

-T _3.4 W ₃ + (S _3.4 + S _4.5 ) W ₄ -T _4.5 W ₅ = -T _3.4 [u ₃ ] -T _4.5 [u ₅ ];

-T _4.5 W ₄ + (S _4.5 + S _5.6 ) W ₆ -T _5.6 W ₆ = -T _4.5 [u ₄ ] -T _5.6 [u ₆ ];

-T _5.6 W ₅ + (S _5.6 + S _6.7 ) W ₆ -T _6.7 W ₇ = -T _5.6 [u ₅ ] -T _6.7 [u ₇ ];

-T _6.7 W ₆ + S _6.7 W ₇ + c _7.8 (W ₇ -W ₈ ) = - T _6.7 [u ₆ ];

S _8.9 W ₈ + c _7.8 (W ₈ -W ₇ ) -T _8.9 W ₉ = -T _8.9 [u ₉ ];

-T _8.9 W ₉ + (S _8.9 + S _9.10 ) W ₉ -T _9.10 W ₁₀ = -T _8.9 [u ₈ ] -T _9.10 [u ₁₀ ];

-T _9.10 W ₉ + (S _9.10 + S _10.11 ) W ₁₀ -T _10.11 W ₁₁ = 0;

-T _10.11 W ₁₀ + (S _10.11 + S _11.12 ) W ₁₁ -T _11.12 W ₁₂ = 0;

-T _11.12 W ₁₁ + S _11.12 W ₁₂ + c _12.13 (W ₁₂ -W ₁₃ ) = 0;

S _13.14 W ₁₂ + c _12.13 (W ₁₃ -W ₁₂ ) -T _13.14 W ₁₄ = 0;

-T _13.14 W ₁₃ + S _13.14 W ₁₄ + c _14.15 (W ₁₄ -W ₁₅ ) = 0;

S _15.16 W ₁₅ + c _14.15 (W ₁₅ -W ₁₄ ) -T _15.16 W ₁₆ = 0;

-T _15.16 W ₁₅ + (S _15.16 + S ₁₆ , ₁₇ ) W ₁₆ -T _16.17 W ₁₇ = 0;

-T _16.17 W ₁₆ + (S _16.17 + G _17.18 + G _17.19 + c ₁₇ ) W ₁₇ -H _17.18 W ₁₈ + D _17.18 φ ₈ -H _17.19 W ₁₉ + D _17.19 φ ₉ = 0;

-H _17.18 W ₁₇ + (G _17.18 + c ₁₈ ) W ₁₈ -K _17.18 φ ₁₈ = 0;

D _17.18 W ₁₇ -K _17.18 W ₁₈ + A _17.18 φ ₁₈ = 0;

-H _17.19 W ₁₇ + (G _17.19 + c ₁₉ ) W ₁₉ -K _17.19 φ ₁₉ = 0;

-D _17.19 W ₁₇ -K _17.19 W ₁₉ + A _17.19 φ ₁₉ = 0,

Where:

, $$T_{nk}=\frac{E_{nk}\cdot F_{nk}}{l_{nk}}+\frac{{\mu }_{nk}\cdot l_{nk}}{6}\cdot {\omega }^2$$

; $$S_{nk}=\frac{E_{nk}\cdot F_{nk}}{l_{nk}}-\frac{{\mu }_{nk}\cdot l_{n\mathrm{<figure-callout\; id="3"\; label="k"\; filenames="00000028.png,00000029.png"\; state="\{\{state\}\}">k</figure-callout>}}}{3}\cdot {\mathrm{<figure-callout\; id="2"\; label="\omega "\; filenames="00000028.png,00000029.png"\; state="\{\{state\}\}">\omega </figure-callout>}}^2$$

, $$T_{nk}=\frac{E_{nk}\cdot F_{nk}}{l_{nk}}+\frac{{\mu }_{nk}\cdot l_{n\mathrm{<figure-callout\; id="6"\; label="k"\; filenames="00000028.png,00000030.png"\; state="\{\{state\}\}">k</figure-callout>}}}{6}\cdot {\mathrm{<figure-callout\; id="2"\; label="\omega "\; filenames="00000028.png,00000029.png"\; state="\{\{state\}\}">\omega </figure-callout>}}^2$$

;

; [u_k]=[u_n]; $$[u_n]=-\frac{{\mu }_{kn}{V}_0{l}_{kn}^2}{E_{kn}{F}_{kn}(\mathrm{one}+i\omega {\gamma }_{kn})}\cdot \frac{\mathrm{one}-\cos {\alpha }_{kn}}{{\mathrm{<figure-callout\; id="2"\; label="\alpha \; k\; n"\; filenames="00000028.png,00000029.png"\; state="\{\{state\}\}">\alpha \; </figure-callout>}}_{kn}^{}}$$

; [u _k ] = [u _n ];

; $${\text{A}}_{\text{nk}}={\text{i}}_{\text{nk}}{a}_{\text{nk}};$$

; $$i_{nk}=\frac{E_{nk}{J}_{nk}}{l_{nk}}$$

; $${\alpha }_{kn}=\omega l_{kn}\sqrt{\frac{{\mu }_{kn}}{F_{kn}{E}_{kn}(\mathrm{one}+i\omega {\gamma }_{kn})}}$$

; $${\text{A}}_{\text{nk}}={\text{i}}_{\text{nk}}{a}_{\text{nk}};$$

; $$i_{nk}=\frac{E_{nk}{J}_{nk}}{l_{nk}}$$

;

; $${\lambda }_{nk}=l_{nk}\cdot \sqrt[4]{\frac{{\mu }_{nk}\cdot {\omega }^2}{E_{nk}\cdot J_{nk}}}$$

; $$a_{\text{nk}}=\left(\sin {\lambda }_{nk}\cdot ch{\lambda }_{nk}\cdot \cos {\lambda }_{nk}\right)\cdot {\lambda }_{nk}\cdot t_{nk}$$

; $${\lambda }_{nk}=l_{nk}\cdot \sqrt[\mathrm{four}]{\frac{{\mu }_{nk}\cdot {\omega }^2}{E_{nk}\cdot J_{nk}}}$$

;

; $$k_{nk}=sh{\lambda }_{nk}\cdot \sin {\lambda }_{nk}\cdot {\lambda }_{nk}^2\cdot t_{nk}$$

$$\frac{\mathrm{one}}{t_{nk}}=\mathrm{one}-\cos {\lambda }_{nk}\cdot ch{\lambda }_{nk}$$

; $$k_{nk}=sh{\lambda }_{nk}\cdot \sin {\lambda }_{nk}\cdot {\lambda }_{n\mathrm{<figure-callout\; id="2"\; label="k"\; filenames="00000028.png,00000029.png"\; state="\{\{state\}\}">k</figure-callout>}}^2\cdot t_{nk}$$

; $$G_{nk}=\frac{i_{nk}}{l_{nk}^2}{g}_{nk}$$

; $$H_{nk}=\frac{i_{nk}}{l_{nk}^2}{h}_{nk}$$

; $$K_{nk}=\frac{i_{nk}}{l_{nk}}{k}_{nk}$$

; $$D_{nk}=\frac{i_{nk}}{l_{nk}}{d}_{nk}$$

; $$G_{nk}=\frac{i_{nk}}{l_{nk}^2}{g}_{nk}$$

; $$H_{nk}=\frac{i_{nk}}{l_{nk}^2}{h}_{nk}$$

; $$K_{nk}=\frac{i_{nk}}{l_{nk}}{k}_{nk}$$

;

; $$h_{nk}=(\sin {\lambda }_{nk}+sh{\lambda }_{nk})\cdot {\lambda }_{nk}^{}{}^3\cdot t_{nk}$$

; $$d_{nk}=(ch{\lambda }_{nk}-\cos {\lambda }_{nk})\cdot {\mathrm{<figure-callout\; id="2"\; label="\lambda \; n\; k"\; filenames="00000028.png,00000029.png"\; state="\{\{state\}\}">\lambda \; </figure-callout>}}_{nk}^{}{}^2\cdot t_{nk}$$

; $$h_{nk}=(\sin {\lambda }_{nk}+sh{\lambda }_{nk})\cdot {\mathrm{<figure-callout\; id="3"\; label="\lambda \; n\; k"\; filenames="00000028.png,00000029.png"\; state="\{\{state\}\}">\lambda \; </figure-callout>}}_{nk}^{}{}^3\cdot t_{nk}$$

;

; $$g_{nk}=(\sin {\lambda }_{nk}\cdot ch{\lambda }_{nk}+sh{\lambda }_{nk}\cdot \cos {\lambda }_{nk})\cdot {\mathrm{<figure-callout\; id="3"\; label="\lambda \; n\; k"\; filenames="00000028.png,00000029.png"\; state="\{\{state\}\}">\lambda \; </figure-callout>}}_{nk}^{}{}^3\cdot t_{nk}$$

;

n, k are indices indicating the beginning and end of the section, respectively;

j is the node number (i = 1, 2 ... 19);

;i is the imaginary unit $$\sqrt{i}=-\mathrm{one}$$

;

J _nk is the axial moment of inertia of the section of the section nk, m ⁴ ;

E _nk is the elastic modulus of the plot nk, Pa;

F _nk is the cross-sectional area of the plot nk, m ² ;

l _nk is the length of the plot nk, m;

;µ _nk is the mass of the unit length of the rod of the plot nk, $$\frac{\mathrm{to}g}{m}$$

;

V ₀ - the speed of impact with the workpiece, m / s;

γ _nk is the coefficient of resistance of the plot nk;

ω is the oscillation frequency, s ^-1 ;

W _j - j-th moving assembly, m;

φ _j is the angle of rotation of the j-th node, rad;

;c _j - stiffness of the springs, modeling the elastic base in the j-th node, $$\frac{\mathrm{to}g}{m}$$

;

.c _nk - stiffness of the springs modeling joints nk, $$\frac{\mathrm{to}g}{m}$$

.

From this system, there are images of displacements in the nodes of the system. Knowing the movement of the beginning and end of the rod, the longitudinal forces N _i (ω) are calculated (Fig. 4). Turning to the originals N (t) are the stresses σ (t) and strain ε (t), which are associated with the efforts of the following relationships (figure 4):

; $$\epsilon (t)=\frac{N(t)}{EF}$$

, $$\sigma (t)=\frac{N(t)}{F}$$

; $$\epsilon (t)=\frac{N(t)}{EF}$$

,

where: σ (t) is the voltage, Pa;

N (t) is the longitudinal force, H;

t is the time, s;

ε (t) - strain, m;

F is the cross-sectional area, m ² ;

E is the modulus of elasticity, Pa.

In the course of the research, an informative frequency range was revealed that made it possible to identify the obtained AFCs. To this end, an analysis was made of the vibration spectrum of the falling parts of the hammer during a hard impact and upon impact on workpieces of various sizes and materials with different impact velocities in the frequency range from 0 to 500 s ^-1 at various nodes of the core system.

All further calculations are carried out in the identified informative frequency range. Variable parameters during hammer operation include impact speed, material, and forging dimensions. Theoretical studies have shown that the stresses arising in various nodes of the system during the collision of falling parts with the workpiece are affected by all of the above parameters, while an increase in the collision velocity leads to an increase in stresses. This allows us to draw conclusions about the influence of the size of the workpiece on the emerging stresses and the frequency of natural vibrations in 3 nodes (the place of rod stocking in a woman).

All possible combinations of lengths and parameters of the workpieces are analyzed within the range of acceptable values for them. The length of the workpiece can take values up to 0.6 m, because the height of the working area for the considered model of the hammer is 0.63 m, and the diameter should not exceed 0.3. It is observed that with a fixed diameter, the voltages fall with increasing length, and the larger the diameter, the higher the voltage. At a fixed length, stresses increase with increasing diameter. With a simultaneous increase in the length and diameter, the stresses also increase, and in the opposite case, respectively, decrease. It is established that when the falling parts collide with a steel billet at a speed of 5 m / s, the maximum stress in the rod, depending on the size of the billet, is possible up to 90 MPa. When speed increases or decreases, voltages increase or decrease accordingly. Considering that the maximum possible collision velocity is 7.1 m / s, stresses at the place of stem insertion into the head can reach (130-150) MPa.

It was established that the maximum stresses, several times higher than the stresses in other nodes of the system, arise at the site of the rod plugging into the shaft (5th node of Fig. 5), which confirms preliminary information from practice on the overwhelming number of breakdowns in this section.

The following way is proposed to reduce the loads that occur at the place of stemming into the woman. You can distribute the load across several sections. To do this, as a new rod design, use a rod with a blind axial stepped hole, the steps of which are located with a decrease in their diameter from one end opposite to the location of the rod in the hammer hammer (Fig.2).

In the dynamic analysis of structures with such a rod, a voltage reduction of 3 knots was obtained by 15% in the case of a steel billet and by 16% in the case of aluminum.

This is achieved by redistributing stresses at 2, 3, 4, and 5 nodes. So, when using the proposed rod design, the voltage in the problematic 5th section decreases from 31.2 to 27.5 MPa in the case of a steel billet and from 20.3 to 17 MPa in the case of aluminum. And in the second and third nodes, the voltages increase approximately three and two times, respectively, which is insignificant compared to the voltage at 5 nodes. In this case, there is a decrease in stresses (5-6)% in the remaining nodes of the system (Fig.6).

The results of a comparison of theoretical and experimental results showed that the average calculation error is 14% for natural frequencies and 25% for vibration amplitudes (Fig. 7).

The proposed changes in the rod design reduce the stresses occurring at the place of the rod stemming into the shaft by (18-20)% and are aimed at increasing the reliability of the rods, which allows to increase their service life and, thereby, reduce material losses from rod replacement and equipment downtime in period of their replacement.

Claims (1)

Forging hammer stock, characterized in that it is made with a blind axial stepped hole, the steps of which are located with decreasing diameter from the end of the stem, opposite to the place where it is embedded in the hammer head.

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