RU2098259C1 - Method of static-pulse working by surface plastic deformation - Google Patents

Abstract

FIELD: technique of finishing-hardening working of parts from steel and alloys by surface plastic deformation. SUBSTANCE: plastic deformation is accomplished by tool to which constant static load and periodic pulse load are applied normally to treated surface. Periodic pulse load is applied by means of striker and waveguide. Mathematical relations are offered for determination of shape, amplitude, duration and frequency of single pulses of deformation force. EFFECT: higher efficiency. 3 cl, 2 dwg, 1 tbl

Description

 The invention relates to mechanical engineering technology, in particular to methods for finishing and hardening processing of parts from steels and alloys by surface plastic deformation.

 A known method of hardening the outer cylindrical surfaces and fillet transitions with a vibrating roller [1] in which the feed movement and the processing speed of the tool and the workpiece are contacted under constant static and periodic pulsed load from a pneumatic riveting hammer applied normally to the machined surface. The method has a high energy intensity, low efficiency, insufficiently large depth of the hardened layer and insufficiently high degree of hardening of the treated surface.

 A known method of finishing and hardening of parts by rolling [2] in which the feed motion and the processing speed of the tool and the workpiece are contacted under a constant static load applied normally to the surface being machined in the range of forces ensuring the movement of a given roughness and periodic impulse load, which varies in the set range from minimum to maximum value. The frequency of the ripple load is selected depending on the required depth of hardening. The method is characterized by low efficiency, the greatest depth of the reinforcing layer.

 The technical result of the invention is the expansion of the technological capabilities of static-pulse treatment by surface plastic deformation by increasing the efficiency of the process, increasing the depth of the hardened layer and the degree of hardening.

 The technical result is achieved due to a more complete realization of the energy of the additional pulsed action, the efficient use of the energy of reflected deformation waves when exposed to a pulsed load of the tool through the striker and waveguide.

 In FIG. 1 is a diagram of a static-pulse treatment by surface plastic deformation; in FIG. 2 is a diagram of the formation of an impulse of deformation force in a contact patch of a tool and a workpiece.

 The method of static-pulse treatment by surface plastic deformation is as follows.

где Pk(t); Pk_i; Pk_max текущее значение гп i-том временном интервале и амплитуда динамической составляющей силы деформирования соответственно H;
P_ст статическая составляющая силы деформирования, H;
m количество волн деформации, действующих на обрабатываемую поверхность в течение одного динамического цикла;
V скорость обработки, м/мин;
i порядковый номер временного интервала и отраженного импульса;
z количество импульсов, формирующих максимальную амплитуду силы деформирования;
E[L₁/(2•L₂)] целая часть числа [L₁/(2•L₂)]
D диаметр обрабатываемой поверхности, мм;
R приведенный радиус деформирующей поверхности инструмента, мм;
S подача инструмента относительно обрабатываемой поверхности, мм/мин;
R_z высота микронеровностей обрабатываемой поверхности по R_z, мм;
НД величина пластической твердости обрабатываемого материала, МПа;
η_нд динамический коэффициент пластической твердости обрабатываемого материала;
W скорость перемещения бойка в момент удара по волноводу, м/с;
C₁, C₂ ударная жесткость бойка волновода соответственно, кг/с;
L₁, L₂ длина бойка и волновода соответственно, кг/с;
E₁, E₂ модуль упругости материала бойка и волновода соответственно, Па:
F₁, F₂ площадь поперечного сечения бойка и волновода соответственно, м₂;
ρ₁, ρ₂ плотность материала бойка и волновода соответственно, кг/м₃;
b, ψ коэффициенты;
Заготовку 1 устанавливают в патроне 2 или (и) центрах 3 токарного станка, а деформирующее устройство 4, оснащенное механизмами статического и импульсного нагружения инструмента, в резцедержателе станка 5 (фиг. 1). Инструменту и заготовке сообщают движение подачи и скорости обработки, вводят их в контакт. В направлении нормали к обрабатываемой поверхности к деформирующему инструменту прикладывают постоянную статическую и периодическую импульсную нагрузку.

where Pk (t); Pk _i ; Pk _{max the} current value of the GP i-th time interval and the amplitude of the dynamic component of the deformation force, respectively, H;
P _{article the} static component of the deformation force, H;
m is the number of deformation waves acting on the surface to be treated during one dynamic cycle;
V processing speed, m / min;
i serial number of the time interval and the reflected pulse;
z is the number of pulses forming the maximum amplitude of the deformation force;
E [L ₁ / (2 • L ₂ )] the integer part of the number [L ₁ / (2 • L ₂ )]
D diameter of the processed surface, mm;
R is the reduced radius of the deforming surface of the tool, mm;
S tool feed relative to the work surface, mm / min;
R _{z the} height of the microroughness of the treated surface according to R _z , mm;
ND is the value of plastic hardness of the processed material, MPa;
η _nd dynamic coefficient of plastic hardness of the processed material;
W is the velocity of the striker at the moment of impact on the waveguide, m / s;
C ₁ , C ₂ impact stiffness of the striker of the waveguide, respectively, kg / s;
L ₁ , L _{2 the} length of the striker and the waveguide, respectively, kg / s;
E ₁ , E _{2 the} elastic modulus of the material of the striker and the waveguide, respectively, Pa:
F ₁ , F ₂ the cross-sectional area of the striker and the waveguide, respectively, m ₂ ;
ρ ₁ , ρ _{2 the} density of the material of the striker and the waveguide, respectively, kg / m ₃ ;
b, ψ coefficients;
The blank 1 is installed in the chuck 2 or (and) the centers 3 of the lathe, and the deforming device 4, equipped with mechanisms of static and pulse loading of the tool, in the tool holder 5 (Fig. 1). The tool and the workpiece are informed of the feed movement and processing speed, and they are brought into contact. In the direction of the normal to the workpiece, a constant static and periodic impulse load is applied to the deforming tool.

 Static loading is carried out, for example, by means of a spring 6 mounted on the waveguide 7. The value of the static deformation force is selected as the largest of the elastic material that provides elastic contact deformation of the processed material.

 Pulse loading is carried out by hitting the striker 8 at the end of the waveguide 7 (Fig. 2), which is an instrument. As a result of an impact, shock-wave pulses of opposite amplitude and duration occur in the striker and waveguide, each of which will affect the surface being treated with a cycle equal to double pulse duration. Having reached the surface to be treated, the shock pulse is distributed on the passing and reflecting. The transmitted pulse forms the dynamic component of the deformation force.

Pk_i=4•W•C₂•[C₁/(C₁+ C₂)]ⁱ⁺¹•(l-e^-b)•(e^-b)^i-1,(2)
z=E[L₁/(2•L₂)]
m=2•z,
b=k•2•L₁/(E₁•F₁),

а частота приложения импульсной нагрузки;
k коэффициент, характеризующий сопротивление обрабатывающего материала внедрению инструмента: k=2,3•10⁷.8•10⁷Н/м;
В результате статико-испульсной обработки поверхностным пластическим деформированем можно воздействовать на обрабатываемую поверхность импульсом заданной формы, амплитуды и продолжительности, адаптированной к обрабатываемому материалу, что позволяет повысить качество обрабатываемой поверхности детали. Предварительное статическое нагружение обрабатываемой поверхности в упругой области позволяет создавать условия для увеличения количества энергии динамического воздействия, затрачиваемого на пластическую деформацию.The reflected shock pulse, reaching the end of the waveguide, is in contact with the striker, distributed between the striker and the waveguide: part of it will go through the striker, and some, reflected with the opposite sign, will again affect the surface to be treated. When the ratio of the length of the striker and the waveguide is more than two (L ₁ / L ₂ > 2) (Fig. 2), the tail portion of the deformation force pulse, consisting of reflected shock pulses superimposed on one another, is superimposed on the head part. The current value of the deformation force is determined by the formula

Pk _i = 4 • W • C ₂ • [C ₁ / (C ₁ + C ₂ )] ^{i + 1} • (le- ^b ) • (e- ^b ) ^i-1 , (2)
z = E [L ₁ / (2 • L ₂ )]
m = 2 • z,
b = k • 2 • L ₁ / (E ₁ • F ₁ ),

and the frequency of application of the pulse load;
k coefficient characterizing the resistance of the processing material to the introduction of the tool: k = 2,3 • 10 ⁷ .8 • 10 ⁷ N / m;
As a result of static-pulse treatment with surface plastic deformation, it is possible to influence the surface to be treated with a pulse of a given shape, amplitude and duration adapted to the material being processed, which improves the quality of the surface of the workpiece. Preliminary static loading of the treated surface in the elastic region allows creating conditions for increasing the amount of energy of the dynamic action expended on plastic deformation.

где Ak_i количество энергии, переданное в обрабатываемую поверхность единичным импульсом силы деформации;
Ak количество энергии, передаваемое в обрабатываемую поверхность.The use of a waveguide during static-pulse hardening makes it possible to increase the amplitude of a single impulse of the deformation force in comparison with the direct impact on the treated surface by 1.3.1.5 times. Accordingly, this increases the amount of energy transferred to the processed surface by 2.2.3 times:

where Ak _{i is the} amount of energy transferred to the surface to be treated with a single impulse of deformation force;
Ak is the amount of energy transferred to the work surface.

The striker and the waveguide are made in the form of rods of the same diameter, and the ratio of their lengths is selected from a range of 2.10 depending on the value of the coefficient characterizing the resistance of the processed material to tool penetration, the value of which for metals is 2.3 • 10 ₇ .7.8 • 10 ₇ N / m Following these recommendations, it is possible to increase the amplitude of the deformation force impulse, and therefore, according to (6), (7), the fraction of energy transmitted to the treated surface by 4.20%
Example. Given: for steel 20-ND = 1440 MPa,
for steel 30HGSA-ND = 4710 MPa,
F ₁ = F ₂ = 0.00049 m ² , E ₁ = E ₂ = 2 • 10 ¹¹ , L ₁ = 0.6 m, L ₂ = 0.06 m, W = 10 m / s, ρ ₁ = ρ ₂ = 8000 kg / m ³ , R = 5 mm.

 The calculation results by the formula (2) are shown in the table.

The table shows that the additional energy obtained through the use of reflected deformation waves is about 6% for steel 20 and 13% for 30KhGSA steel
An analysis of the results shows that with an increase in the resistance to tool penetration into the metal, the amount of transmitted energy Ak into the work surface increases under the influence of the first single impulse of the deformation force. However, the fraction of the energy of the superimposed reflected pulses on the first decreases. It follows that it is advisable to process a more pliable metal with the largest ratio of the striker and waveguide lengths L ₁ / L ₂ ranging from 2 to 10.

Claims (3)

A method of static-pulse treatment by surface plastic deformation, in which a static load and a periodic pulse load are applied to the tool normally to the surface being treated, characterized in that the pulse load is communicated by means of a striker and waveguide, and the shape, amplitude, effective duration and frequency of single pulses of the deformation force are determined by formulas

z E [L ₁ / (2L ₂ )]
m 2 • z;
b K • 2 • L ₁ / (E ₁ • F ₁ );

where P _k (t),

the current value, the value on the i-th time interval and the amplitude of the dynamic component of the strain force, respectively, H;
P _{ct is the} static component of the deformation force, H;
N frequency of application of the pulse load, min ^-1 ;
S feed tool mm / rev. m is the number of deformation waves acting on the surface to be treated during one dynamic cycle;
v processing speed, m / min;
i serial number of the time interval and the reflected pulse;
z is the number of pulses forming the maximum amplitude of the deformation force;
E [L ₁ / (2L ₂ )] the integer part of the number [L ₁ / (2L ₂ )]
R _{z the} required height of the microroughness in R _z , mm;
ND is the value of plastic hardness of the processed material, MPa;
η _ND - dynamic coefficient of plastic hardness of the processed material;
W is the velocity of the striker at the moment of impact on the waveguide, m / s;
L ₁ , L _{2 the} length of the striker and the waveguide, respectively, m;
C ₁ , C ₂ impact stiffness of the striker and waveguide, respectively, kg / s;
E ₁ , E _{2 the} elastic modulus of the material of the striker and the waveguide, respectively, Pa;
F ₁ , F ₂ the cross-sectional area of the striker and the waveguide, respectively, m ² ;
ρ ₁ , ρ ₂ - the density of the material of the striker and the waveguide, respectively, kg / m ³ ;
b, ψ are the coefficients;
K coefficient characterizing the resistance of the processed material to the introduction of the tool, K (2.3 8.0) • 10 ⁷ N / m.  2. The method according to claim 1, characterized in that the magnitude of the static component of the deformation force is selected the largest of the elastic surface deformations of the treated surface.  3. The method according to claim 1 or 2, characterized in that the striker and the waveguide are made in the form of rods of the same diameter, and the length of the striker is 2 10 times the length of the waveguide.

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