JP2022132267A - Micro-vibration press working method for metallic material by punch stroke control - Google Patents

Abstract

To provide a press working method for metallic material in which nano-level microscopic deformation behavior of ferrous and non-ferrous metallic materials is taken into consideration, this is adequately combined with practical macroscopic working condition, thereby enabling realization of excellent press working performance regardless of kinds of metallic materials.SOLUTION: According to a micro-vibration press working method for a metallic material by punch stroke control that vertically moves a punch to vibrate a punch stroke when press working a metallic material, in a punch advancement process in the punch stroke, a processing force to the metallic material is generated at the time of contact between the punch and the metallic material, molding of the metallic material advances, and in a retreat process of the punch and the following advancement process of the punch, a micro-vibration operation for alleviating and leveling nano-level microscopic stress field and strain field that are generated in the metallic material is applied to the punch stroke during non-contact until the punch contacts the metallic material.SELECTED DRAWING: Figure 7

Description

Based on the nano-level microscopic deformation behavior of ferrous and non-ferrous metal materials, the present invention appropriately combines this with practical macroscopic processing conditions to achieve excellent performance regardless of the type of metal material. The present invention relates to a press working method for a metal material that enables realization of press workability.

Elasto-plastic processing of ferrous and non-ferrous metal materials, mainly deep drawing, is conventionally performed at room temperature using mechanical/crank presses, hydraulic presses, and special presses that utilize liquid pressure, ultrasonic waves, electromagnetic force, etc. In recent years, a servo press machine with variable stroke operation is also used. Elastic-plastic working is often performed by cold working at room temperature or hot working at temperatures above the recrystallization temperature. A "fusion processing method" or the like that simultaneously controls the processing temperature and the processing temperature has also been proposed and some have been put into practical use (see Patent Documents 1 to 9 and Non-Patent Documents 1 to 9).
The most common elasto-plastic processing method is when a general-purpose crank press or hydraulic press is used at room temperature. It will be used for comparison with the processing methods related to the invention, and will be used to judge superiority or inferiority with the present invention.

JP-A-54-142168 JP-A-54-143763 JP-A-62-176617 JP-A-11-309518 JP-A-11-309519 WO2013/115401 JP 2015-020208 A JP-A-54-142462 JP-A-07-048589

Shigeyasu Koda: "Introduction to Metal Physics", (1967), [Corona Publishing] Edited by Japan Society for Technology of Plasticity: Handbook of Plasticity Processing, (2008), [Corona Publishing] D. McLean: ``Mechanical Properties of Metals'', (1962), [John Wiley & Sons, Inc.] William C. Leslie: “The Physical Metallurgy of Steels”, (1981) , [McGraw Hill, Inc.] Kiyohiko Nohara: "Efforts to Reduce the Cost of Thin Stainless Steel Sheets and Press Processing Technology," Press Technology (2007), [Nikkan Kogyo Shimbun] Edited by the Japan Institute of Metals: "Handbook of Metals", (2008), [Maruzen Co., Ltd.] Kiyohiko Nohara: "Complete Stainless Steel", (2016), [Nikkan Kogyo Shimbun] K. Nohara, Y. Watanabe and K. Yamahata:” Warm Press Forming of Stainless Steel Sheets “, (1990) , 1st Int. Conf. on New Manufacturing Tech. (Proc.), Japan K. Nohara, M. Shinohara, N. Kawabata, H. Nakamura, K. Miyajima, Y. Yamamoto, H. Hayano, M. Yamanaka, T. Saeki, and S. Kato: “Studies on Innovative Production Methods of HOM Coupler for SRF 9-Cell Cavity”, (2015) , Int. Particle Accelerator Conf.(Proc.), Richmond (Jefferson Lab. ), USA J. A. Elias, R. H. Heyer and J. H. Smith: Trans. AIME, 224 (1962), 679 Tomomi Maeno: "Automatic re-lubrication using low cycle vibration motion using servo press", Press Technology (2008), [Nikkan Kogyo Shimbun]

However, press working by the conventional room temperature working method, the ultrasonic working method, the warm working method, or the fusion working method of the above-mentioned prior art is all of the iron-based and non-ferrous metals that are the workpieces. Macroscopic processing methods, effects, and industrial applications based on observations of phenomena from a microscopic point of view regarding the crystal structure and internal structure of materials at the nano-atomic level (hereafter referred to as "nano-level") and their deformation behavior. Since we have not verified the feasibility of press working, in order to achieve excellent workability, there are various factors such as determination of appropriate conditions, degree of workability improvement, difficulty of work, initial investment, economic efficiency, etc. There was a problem. The object of the present invention is to obtain the results of development of an excellent processing method based on nano-level events and their studies.

That is, the present invention has been made in view of the above problems inherent in the prior art. Based on the nano-level microscopic deformation behavior of ferrous and non-ferrous metallic materials, the purpose is to appropriately combine this with practical macroscopic processing conditions to achieve excellent performance regardless of the type of metallic material. An object of the present invention is to propose a method of press working a metal material that enables realization of press workability.

In view of the above-mentioned current situation in this field, the inventors believe that the macroscopic deformation behavior, that is, the press workability, ultimately depends on the microscopic nano-level internal structure and deformation behavior of the metal material, or the crystal structure and its alteration. Based on the insight that it is controlled, the following studies were conducted, and the present invention was achieved.
i.e.
(1)
When pressing metal materials mainly by drawing,
A micro-vibration press working method for a metal material by means of punch stroke control in which the punch is moved up and down to vibrate the punch stroke,
During the forward movement of the punch in the punch stroke, a working force is generated on the metal material when the punch and the metal material come into contact with each other, and the forming of the metal material progresses.
In the retraction stroke of the punch and the subsequent forward stroke of the punch, when the punch is not in contact with the metal material, nano-level microscopic stress fields and strain fields are generated inside the metal material. The micro-vibration action that alleviates and smoothes the
A micro-vibration press working method for a metal material by punch stroke control, characterized in that it is applied to the punch stroke.
(2)
Assuming that the forward and backward distances of one punch stroke are X _P and X _{r ,}
The traveling distance during this period is ΔX=X _P −X _r,
Further, if the forward and backward speeds are V _P and V _r , and the forward and reverse times are t _P and t _r ,
The traveling speed during this period is ΔV=ΔX/(tP _{+ tr} )=( _VP · _tP )/( _{tP + tr} )≡( _XP +Xr)/( _tP + _tr ),
In this case, the micro-vibration operation is X _P >X _r , (that is, ΔX>0) and V _P >V _r , (that is, ΔV>0) (the forward direction of the punch is + and the backward direction is −). The micro-vibration press working method for a metal material by punch stroke control described in (1), wherein the filling is performed at the same time.
(3)
In the press working by the punch stroke with the fine vibration operation,
Assuming that the movement distance is X and the subscripts _{P and r denote} forward and backward linear motion, respectively,
X>0; 0 mm<X _P ≦100 mm; 0 mm<X _r ≦50 mm; X _P ≧X _r >0;
When the moving speed is V, both conditions of V _P ≥ 1 mm/sec; V _P ≥ V _r > 0 are satisfied. Micro-vibration press processing method.
(4)
The range of the frequency ν (Hz) of the micro-vibration operation applied to the punch stroke is 3 ≤ ν ≤ 10,
The micro-vibration pattern of the punch stroke of forward and backward vibration during machining by servo control from the top dead center to the bottom dead center of the punch stroke is as follows.
Conventional acceleration/deceleration linear constant speed forward/backward constant or non-uniform motion (P ₁ ),
Constant speed forward and backward constant or non-uniform motion (P ₂ ),
or sinusoidal constant angular velocity linear forward and backward uniform or non-uniform motion (P ₃ ),
Or _Pj C _j (j=1 or 2 or 3) combining these
A micro-vibration press working method for a metal material by punch stroke control according to any one of (1) to (3), characterized in that:
(5)
The ratio Ψ _j (j = 1 or 2 or 3) of P _j (j = 1 or 2 or 3) in _Pj C _j (j = 1 or 2 or 3) (assuming that ΣΨ _j = 1) can be arbitrarily set,
The number of repetitions N _i of the frequency ν (Hz) is 1 to 3.
(6)
Assuming that the average moving speed in the press working by the punch stroke with the fine vibration operation is V _ave , the maximum drawing depth is H _max , and the maximum drawing time is T _max ,
respectively,
V _ave =<Σ[∫{(X _P −X _r )/ν}·t]dt>/t _f
Hmax=[∫∫{(X _P −Xr)·ν}dvdt] _max
T _max =Σ<Σ[∫{(1/ν)dν}] _(Ni) > _i
(here, t _f is the time required for drawing out).
(7)
The processing temperature T of the metal material in the press working by the punch stroke with the micro-vibrating operation is based on the crystal system of the metal material under the following conditions Body-centered cubic material: room temperature ≤ T ≤ 200 ° C.
Face-centered cubic material: room temperature ≤ T ≤ 300°C
Dense hexagonal material: room temperature ≤ T ≤ 400°C
A micro-vibration press working method for a metal material by punch stroke control according to any one of (1) to (6), wherein
(8)
When the room temperature is 20° C., the metal material has the following crystal system:
Body-centered cubic materials: pure iron, carbon steel, high-strength steel,
Surface-treated steel, ferrite stainless steel,
β-type titanium alloy, tantalum, niobium Face-centered cubic materials: austenitic stainless steel, aluminum alloy
Copper alloy Close-packed hexagonal material: The micro-vibration press working method for a metal material by punch stroke control described in (7), characterized in that it is a magnesium alloy or an α-titanium alloy.
(9)
Depending on the processing temperature T,
kinematic viscosity Γ is
When T≤40°C: Γ = 25 to 100cSt
When T>40°C: Γ = over 80 ~ 800cSt
The micro-vibration press working method of a metal material by punch stroke control according to (7) or (8), characterized in that the lubricants of (7) and (8) are used, respectively.
(10)
It is characterized by using a servo device that imparts the fine vibration motion to the vertical movement of the punch stroke, and a temperature control device that controls the processing temperature of the die material by heat conduction from a die tool for press drawing. A micro-vibration press working method for a metal material by punch stroke control according to any one of (1) to (9).
(11)
(7) to (9), the molded body subjected to the micro-vibration press working method of a metal material by punch stroke control,
The processing temperature T is
When T = room temperature: in the conventional method,
When T = above room temperature to 200°C: in the warm press method,
A micro-vibration press working method for a metal material by punch stroke control, characterized by applying restrike processing or ironing processing.
(12)
Any one of (7) to (9) or the molded body that has undergone the micro-vibration press working method of a metal material by punch stroke control described in (11),
The processing temperature T is
When T = room temperature: in the conventional method,
When T = above room temperature to 200°C: in the warm press method,
A micro-vibration press working method for a metal material by punch stroke control, characterized by performing drilling or burring protrusion processing.
(13)
A pressed product by a single process that avoids annealing heat treatment and cutting by a machining center by using the micro-vibration press working method for metal materials by punch stroke control according to any one of (1) to (12). A method for manufacturing a pressed product, characterized by manufacturing
and

The present invention will be described in more detail below.
Metal materials, regardless of whether they are iron-based or non-ferrous, consist of microscopic metallographic structures, that is, polycrystalline bodies in which single crystals of various crystal systems are arranged in the front, back, left, right, and up and down directions. This polycrystal consists of an aggregate of many crystals having crystallographically different orientations, ie, many crystal grains. Grains are separated by grain boundaries and joined together to form a polycrystalline metallic material. However, the crystal coordination at the grain boundary is different from that inside the grain, and the coordination is disordered and the structure is also different. It is surmised that the nano-level microscopic deformation behavior that occurs during processing of polycrystalline practical materials with such morphology is the true factor that determines the macroscopic workability.

In the following paragraphs 0009 to 0017 (paragraphs omitted below), metal physical nano-level microscopic deformation behavior will be described.
First, regarding nano-level plasticity during microscopic deformation, the microscopic internal structure of metal single crystals contains non-metallic inclusions and atoms other than the elements that make up the specific metal. Solid solution phenomena, that is, substitution at lattice points, penetration into specific spaces other than lattice points, precipitation reactions of atoms, and segregation phenomena occur, and their non-uniform distribution is unavoidable. In polycrystalline metals, in addition to these phenomena, the presence of grain boundaries causes various phenomena such as stress concentration and deformation pinning, changes in "crystal texture" during working, and localization of grain boundaries due to working heat. Recovery phenomenon, interrelationship between various grain boundary tilt angles and external force, effect of crystal rotation, effect of Schmidt factor, differences in the degree of stacking faults and twinning depending on the type of metal and processing temperature. There are various microscopic phenomena that affect macroscopic workability to a greater or lesser extent. These factors are considered to determine the dynamic behavior, that is, the macroscopic workability by the action of external conditions.
The Schmid factor is the force that causes microscopic slip and is determined by the angle between the external force, the normal to the slip surface, and the slip direction. Therefore, the slip system, which is a combination of the slip surface and the slip direction, is determined by the magnitude of the Schmid factor. This magnitude takes different values depending on the direction within the stereo triangle of the polycrystalline metal material.

Crystalline ferrous and non-ferrous metallic materials, both single crystals and polycrystals, are classified into one of 14 Bravais lattices. In particular, the crystal system of polycrystalline practical metal materials belongs to one of body-centered cubic lattice (BCC), face-centered cubic lattice (FCC), and hexagonal close-packed lattice (HCP).

In these crystal lattices, not all atoms of a given element are present at the lattice point positions according to the crystal system, and there are always "defects" (point defects) lacking the presence of the required atoms, and special treatments such as zonemelting are required. It is not possible to obtain a "perfect crystal" without defects unless carefully performing single crystallization, by-crystal formation, or the like. In addition to the point defects mentioned above, "defects" include line defects and surface defects, and macroscopic deformation/hardening behavior when an external force or load is applied is mainly movement/deformation due to nano-level line defects. be. This line defect, that is, the displacement of the linear arrangement of the crystal lattice that lacks the presence of atoms at lattice points is called "dislocation (line)" (Fig. 1; Non-Patent Document 2). When a dislocation moves (moves) (Fig. 2; Non-Patent Document 1), the magnitude and direction of the dislocation slip are important. This is called the scalar value b of the Burgers vector of the dislocation. "edge dislocations", and parallel dislocations are called "screw dislocations". A linear strain when a local portion of the crystal is displaced by b may be called a dislocation. The dislocation density (ρ), which is the amount of dislocations present in practical metallic materials, is ρ = 10 ⁵ to 10 ⁸ /cm ² , and influences the dynamics during deformation, that is, the generation, movement, propagation, and disappearance of a large number of dislocations. The microscopic behavior and conditions of crystals that give

FIG. 3 (Non-Patent Document 3) and FIG. 4 (Non-Patent Document 4) show examples of optical micrographs and electron micrographs after dislocation micro-slip. Fig. 3 shows a large number of mutually parallel traces (slip bands; corresponding to the direction of load) generated after dislocation motion, and Fig. 4 shows a direct observation image of dislocations after working. It is observed that there are many sites with high density and localized tangling. At the same time, "cross-slip" (dislocations crossing each other and moving) can also be seen here and there. Crossing slips are more likely to occur when the (0041) stacking fault energy, which will be described later, is large and the dislocation extension width is small, because the energy for contraction of the extension dislocations is small. It is expected that the application of micro-vibrating motion will act advantageously in this regard.

Next, "nano-level processing, that is, movement of dislocations" will be described. Movement of dislocations is hindered by the above-mentioned various metal structures, and pile up (state of superimposition) or "field" of stress concentration is generated, causing difficulty in microscopic deformation, and eventually macroscopic deformation. have a negative impact on physical transformation. That is, since it leads to deterioration of drawability, it is difficult to expect improvement thereof.

In view of the above circumstances, the present inventors facilitated the basic movement of dislocations and considered the above-mentioned "microscopic metal structure" and "microscopic deformation behavior". I thought about means to reduce factors that inhibit dislocation movement, such as metals, non-metallic inclusions, grain boundaries (including subgrain boundaries accompanying recovery in some cases), and lattice defects caused by dislocation movement. That is, instead of continuously loading the dislocation dynamic behavior in one direction, the punch is also returned in the opposite direction, that is, by controlling the punch stroke, there is time to relax the nano-level fine internal phenomenon. By giving It is conceived. The reason for this is that by giving a time margin for unloading after working, a phenomenon similar to a mechanical reaction force occurs, or a phenomenon of thermodynamic free energy and entropy increase/decrease occurs, resulting in continued movement of dislocations, In other words, it is due to the inference of the possibility of contributing to the progress of machining.

The specific reasons are as follows. First, we obtain a relational expression for the true strain ε ^* (ductility), which is the amount of deformation due to the movement of microscopic dislocations. The length of the dislocation is l (in this specification, the lowercase letter l (ell) indicating the length of the dislocation is underlined in order to clearly distinguish it from the number 1), and the distance over which the dislocation moves is s. Then, the area A where the dislocation has finished sliding is
A = ls ( 1 )
The crystal volume U is given by:
U = h F (2)
where h is the thickness of the crystal and F is the area of the slip surface. Now, when _n0 dislocations move in parallel, the microscopic/nano-level true strain ε ^* (the true strain in actual press working is ε, which will be described later) is
ε ^* =(n ₀ Ab)/U (3)
but the dislocation density is
ρ=n ₀ /(U/) l (4)
Therefore, ε ^* is finally expressed as:
ε ^* =ρsb (5)
where b is the scalar value of the Burgers vector b of the dislocation.

Microscopic plastic deformation is associated with upward movement and multiplication of dislocations (generation of point defects, activity of Frank-Reid sources (sources in which dislocations propagate due to external force), generation of cross slips, jog (dislocation lines It is caused by the occurrence of a staircase caused by moving from a slip surface to a parallel adjacent slip surface that is one atomic distance away from the slip surface. Assuming that the increase in dislocation density ρ is Δρ, the degree c of increase or decrease in lattice defects (atomic vacancies and interstitial interstitial atoms) in the crystal volume is
c=(A/μ)∫τ ^* (ε ^* )dε ^* (6)
(Here, τ ^* is the nano-level shear true stress; μ is the modulus of rigidity, which can be derived from Young's modulus E and Poisson's ratio π as μ=E/{2(π−1)}; 0 to ε ^* ), and when ε ^* is small, K is a constant,
Δρ=K・ε ^* (7)
, and Δρ becomes relatively large. Also, when ε ^* is large, with J and H as constants,
Δρ=H+ Jlnε ^* (8)
and Δρ becomes relatively small. These are empirically supported.

Secondly, although it is difficult to derive the deformation stress (strength) during microscopic deformation by theoretical calculation, many experimental results indicate that the following relationship exists between the microscopic true shear stress τ ^* and the dislocation density ρ. A correlation given by the formula has been found:
τ ^* = _τ0 ^* +βμb√ρ (9)
where τ ₀ ^* and β are constants. Then, τ ^* is represented by σ ^* cos θ, where σ ^* is the vertical true stress (θ is the angle between the vertical true stress and the shear true stress), so the expression for σ ^* is as follows: become:
σ ^* =( _τ0 ^* +βμb√ρ)/cos θ (10)

Here, in contrast to the microscopic viewpoint of "metal physics" such as 0009 to 0017, cylindrical deep drawing of practical metal materials that can be said to be a typical example of macroscopic processing mode from the viewpoint of "plastic working" , there is the following quantitative interrelationship (0019-0027).

The stress-strain (σ-ε) relationship, which is essential for elasto-plastic processing, will be mainly described. The reason is that the new idea content of imparting micro-vibration motion in the present invention indirectly and This is because it contributes to the understanding of the gist of the present invention, including the origin and mechanism, based on the prediction that it will be connected scientifically.

From a practical and industrial point of view, the evaluation index for deep drawability will be outlined below: First, the work hardening index n and the plastic strain ratio r are defined as follows, and when examining and verifying the drawability Useful:
n=(dσ/dε) and r=|ε _W /ε _t | (11)
Here, ε _W and ε _t represent the width true strain and thickness true strain of the parallel portion in uniaxial tensile deformation, respectively. Since there are cases of "+" and cases of "-", these values are indicated as "absolute values", and both of them serve as a measure of workability.

In uniaxial tensile deformation, it is generally known from actual measurement results that the following relationship holds between the true stress σ and the true strain ε (Ludwick's formula):
σ=Cε ⁿ (12)
Here, σ during work deformation of the polycrystalline metal material follows the equation (12) and at the same time depends on the strain rate (dε/dt) and the deformation temperature T as follows:
σ=F・ε ⁿ・(dε/dt) ^m (13)
lnσ =B+(Q/kT) (14)
Here, F and B are constants, m is the strain rate sensitivity index, Q is the activation energy, and k is the Boltzmann constant. These relationships are also useful when considering workability.

Here, in deep drawing, the frictional force between the die and wrinkle holding tool and the material surface accompanying deformation, that is, the flange deformation resistance is _Pd , and the critical rupture resistance of the metal material is _Pf . The latter is a deformation state diagram showing fracture force diagrams of various deformation modes in an orthogonal coordinate system consisting of ε _X and ε _Y , in which the deformation state of the compact is always in the deformation state (ε _x = 0, ε _y ). A certain deformation mode is called a "plane strain deformation mode", the critical rupture true stress _σcr is expressed in this case, Pf is expressed in this case, and the deformability is the smallest compared to other deformation modes. In the processing of _compacts including various deformation _modes , the plastic The size relationship in the vicinity of the boundary between the stable region and the plastically unstable region determines the limit of formability in drawability. In other words, in order to continue processing without breaking,
P _f >P _d (15)
must be satisfied. In the processing by various deformation modes corresponding to this critical zone, if the true stress σ corresponding to the critical zone just before that critical zone is σcr as described above, this value can be obtained using n and r and the plate thickness (t) as follows:
σ _cr =(2+√3) ¹⁺ⁿ ·[{(1+R)/2}/{(1+2R) ^1/2 /3}] ¹⁺ⁿ ·σ _u (t ₀ /t _f ) (16)
is shown (Non-Patent Document 7). Note that σ _u is the tensile true stress (tensile strength) in uniaxial tensile deformation.
Here, R is the average value of r, that is, the rolling direction angle when the material is cold rolled is 0 °, and the r values in each direction of 90 ° and 45 ° from there are r ₀ , r _90, r ₄₅ is defined by the calculated value in the following formula:
R≡(r ₀ +r ₉₀ +2r ₄₅ )/4 (17)
t ₀ and t _f are the average values of the initial plate thickness before processing and the plate thickness of the fracture surface after fracture, respectively.

In addition, by using the fact that the volume or weight of the material does not change before and after deformation, applying a simple differential calculation to equation (12) yields
n= _εu (18)
A theoretical relationship of Here, ε _u is the value of ε corresponding to tensile strength. This formula is convenient when examining and estimating workability from uniaxial tensile test data.

By the way, the conventional stress S and the conventional strains λ, σ, and ε, which are generally used for commercial transactions, are linked to each other by the following relational expressions when differential and integral calculations are performed, starting from their definitions. However, in the plastic deformation region in actual machining, that is, deformation between S ₀ and S _max , although it does not completely match the theoretical formula, it can be regarded as a useful approximation formula, and formulas (19) and (20) ) may be used. :
σ=S(1+λ) (19)
ε=ln( 1 +λ) (20)

In addition, as an index for comparing formability such as deformability in cylindrical drawing, from the viewpoint of plastic working, the "drawing ratio" DR and its limit value, that is, when drawing is done without breaking or wrinkling A corresponding "critical draw ratio" LDR is often used. However, problems such as "plastic anisotropy (earing)" remain. Each expression is defined by the following equation, where D _p is the diameter of the punch and D ₀ is the diameter of the circular blank as the base plate:
DR[identical to]( _D0 / _Dp ); LDR[identical to]( _D0 / _Dp ) _max (21)
The reciprocals of these are called "drawing ratios", which also serve as an evaluation index.

Furthermore, if the drawability is represented by the drawing depth H (equal to the moving distance (stroke) in one direction from the top dead center of the punch to the bottom dead center), it is easy to intuitively judge the workability. , where τ is the plate thickness reduction rate due to drawing, and the blank weight does not change before and after processing, so in the case of an isotropic material,
H _max =<(D _p /4)[{(D ₀ /D _p ) ² /(1−τ)}−1]> _max (22)
(Patent Document 7).
When illustrated, H _max is indicated by yD _p (y: variable), and it is easier to see if it is expressed by the yD _p -DR relationship (see FIG. 10). Here, H _max corresponding to LDR represents the maximum drawing depth.

LDR can be expressed by the following equation as a function of the n value and r value (using the average value R of the r value shown in equation (17) for analysis) in the case of flat-bottomed cylindrical drawing (Non-Patent Document 2) :
LDR=(1+R) ² ·{(1+R)/(1+2R) ^1/2 } ⁿ (23)
However, in order to be moldable, as can be seen from the formula (15),
η≡P _f /P _d >1 (24)
must be satisfied.

As described above, regarding the processing of metal materials mainly by drawing, "microscopic metal structure and deformation behavior mainly based on the existence and behavior of dislocations" based on nano-level "metal physics" and macroscopic practical application ``Macroscopic deformation behavior and its evaluation index centered mainly on deep drawing'' based on ``plastic working science'' at the working level was investigated.
The reason and purpose is to provide an understanding of the means and effects of the invention.

The inventors considered that the macroscopic deep drawing performance is closely related to the properties of microscopic dislocations, as shown in FIG. It was presumed that it is essential to control. The present invention is based on the fact that a large number of dislocations, which are microscopic line defects, are present in the material that is delivered after being blunted, and that the dislocations migrate and proliferate due to the load of an external force, but the degree of the dislocations decreases rapidly, resulting in deformation. In order to avoid the difficulty of the behavior, it was conceived to provide a working time and an unloading time by applying a micro-vibration motion, and came up with the idea of improving the deep drawing ability.

From the macroscopic analysis, considering that the deep drawability is related to the n value and the r value as described above, the n value and the r value can be controlled by the external action on the dislocations from the following two microscopic viewpoints. I thought it would be.

The first is that the formation and mobility of dislocations will be changed by the “application of microvibration”. In other words, the punch moves in one direction as a whole (machining the material) while causing the punch to vibrate in both vertical directions. (the contact period between the material and the punch)", and the situation of microscopic dislocations that hinder further movement and the internal state of microscopic dislocations that hinder further movement caused by the non-contact state of the two during the working period are improved ( The amount of dislocations generated (dislocation density) should be changed by alternately providing “non-working periods (non-contact periods between the material and the punch)”, which correspond to the time margins due to the release and dispersion of the stress field and strain field. Brazing also affects the state of motion of dislocations, changes the degree of difficulty of mobility, reduces (mitigates) the degree of decrease in the n-value, which is unavoidable due to deterioration (decrease) due to processing, and deep drawability becomes advantageous. I expected that it would be possible to control

Part 2: In general, the r value decreases due to processing, but by "applying microvibration motion", the distribution and density of dislocation formation are made uniform (especially within the plate thickness) of the material, and the dynamic r value (external force The r value has stress dependence depending on the load), but the decreasing tendency is lower than when microvibration is not applied, and the degree of reduction in the thickness of the material is moderated, so deep drawability can be improved. I came to the conclusion that I was deaf.

The reason why these 0031 and 0032 occur is that, among the various phenomena related to dislocation movement, the "application of microvibration motion" is related to the following microscopic items, and the moldability is improved. This is because I predicted that it would contribute to the improvement and actually found out. The five viewpoints are summarized below.

1) When the material is subjected to external force working, new dislocations are generated and proliferated, and grain boundaries, precipitates, impurities such as oxides and sulfides, solid solution atoms, etc., which exist unevenly in the annealing state It is conceivable that stress concentration occurs at the same time that it accumulates and creates strain/stress fields. It is predicted that the time for easing such a situation is ensured by "applying micro-vibration motion", the thermodynamic free energy tends to decrease, and the microstructure is homogenized. This contributes to improving moldability.

2) It is expected that the three-dimensional dislocation distribution/arrangement will be maintained in a relatively uniform state due to the "application of micro-vibration motion" and the deformation will progress, and "cross-slip" will be facilitated to a considerable extent. Since it is considered to occur more easily, the deformation progress will be made with a relatively small external force/stress. Since the possibility of such a phenomenon occurring is sufficiently conceivable from the viewpoint of materials, this leads to an improvement in moldability.

3) When processing is performed while executing the behavior of "micro-vibration operation", forming processing, for example, deep drawing, progresses with the contact between the punch and the material to be processed, and dislocations are generated inside during the non-contact time period. A state change occurs. That is, it is expected that the variability of material deformation and hardening will be facilitated by controlling the appropriate external conditions using the movement of operating dislocations as the basic process. Therefore, it is possible to control the n-value and r-value depending on the material type and the transition behavior of the crystal texture. In other words, moldability can be controlled.

4) The crystal system of metallic materials is mostly either BCC, FCC or HCP. The slip plane and slip direction of each crystal system originating from the dislocation are crystallographically and thermodynamically determined. For example, the major slip deformation of BCC is {110}<111> (the minor slip deformations are {112}<111> and {123}<111>). Here, generally {hk l } is the Miller index of each crystal plane, and <uvw> is the Miller index indicating each crystal orientation. In the case of BCC, the slip direction of micro-slip deformation is <111>, but from a different point of view, it is calculated that if the {111} planes accumulate in the plane perpendicular to the vertical direction of the material surface, micro-slip is likely to occur. and experimentally demonstrated (Non-Patent Document 10).

The principal slip plane/direction of FCC is {111}<110>, and the principal slip plane/direction of HCP is {1000}<1110>. Both have fewer slip systems than BCC.

When macroscopic deformation progresses due to the application of microvibration action to the punch, which is completely different from conventional ultrasonic vibration machining intended for hammering effect and lubricant dispersion effect, by applying a load in the horizontal direction to the die, 0037 and Considering 0038, in any crystal system, the crystal plane / orientation indicated by {hk l } <uvw> (the stroke distance in the processing direction is set larger than the stroke distance in the opposite direction for each vibration) "Crystal rotation" and "rearrangement of dislocations" become easier in the process of slip progress, and it is speculated that this has an advantageous effect on workability itself. As an example of known vibration machining, there is "ultrasonic machining" described in 0045.

5) Although it depends on the type of metal material and processing temperature, the energy that determines the difficulty of generating stacking faults SF (a planar defect phenomenon in which the stacking of atoms as crystals does not follow a certain period and causes “shift”), that is, When the stacking fault energy SFE is small, the width of the dislocation is expanded by an external force, resulting in "twin deformation". Plastic deformation (permanent deformation) of a material consists of the sum of both "slip deformation" and "twinning deformation" mentioned above. hindrance to By "providing micro-vibration motion", it becomes difficult for the SFE to decrease, the formation of extended dislocations is suppressed, and twinning becomes difficult to occur. can be expected. As a result, it was inferred that it acts favorably on molding.

A large stacking fault energy means that stacking faults are less likely to occur, so that "cross slip" tends to occur during slip deformation behavior, which can improve moldability. It can be expected that such a workability-enhancing phenomenon will function through the interrelationship between the "application of micro-vibration motion" and the stacking fault energy.

The qualitative relationship between the punch stroke and some of the above nano-level microscopic effects, such as dislocation density, dislocation rearrangement and crystal rotation, cross slip, stacking faults and twinning, is shown schematically. FIG. 6 schematically shows this. The characteristics of both processing methods are shown by comparing the conventional method and the “micro-vibration press processing method”.

Furthermore, regarding the forming processability of practical metal polycrystalline materials, such as deep drawability, it is based on the generation of dislocations, which are microscopic line defects, and the change in mobility accompanying the "imposition of microvibration motion". From the consideration of the mechanism of properly controlling the influence on the r-value and the influence on the related microscopic phenomenon change based on the homogenization of the distribution and density of dislocation formation, especially within the plate thickness, The possibility of improving macroscopic plastic deformability/formability was conceived. In short, if σ _cr is σ _cr ^* when micro-vibration motion is applied,
σ _cr ^* >σ _cr (25)
I found out the feasibility of

Next, the means and conditions of the present invention relating to application of micro-vibration motion in practical use will be described below based on the results of basic and development studies.

As suggested in 0039, conventionally, for "vibration working" related to press working, "ultrasonic machining method" is known (Non-Patent Document 2). Methods are being considered. The purpose of application to deep drawing is to intermittently apply the vibration generated by the ultrasonic device to the die and the mold tool that is a wrinkle holder to achieve the hammering effect of the flange and indirectly the lubrication effect to the blank. , and does not apply vibration to the nano-level microscopic deformation behavior of the work material of the present invention and to the punch that makes direct contact with the work material to progress deformation processing.
Further, unlike the present invention, it is nothing more than a single vibration transmitted to the tool, which is different in frequency and pattern from the present invention, and has not been put into practical use. The reasons for this are the lack of improvement in workability, the lack of operability and stability of machinery, the high cost of ultrasonic instruments and tools, and the unclear relationship between processing phenomena and processing conditions. be.

With the spread of servo press machines, a method of "automatic relubrication using low cycle motion" in forging has been made public (Non-Patent Document 11), but this Using elastic deformation and plastic deformation of the material, the slide is lifted and unloaded several times during the forging process, lubricating the material through gaps around the material and re-lubricating the slide, using a servo mechanism. However, no consideration is given to the nature of the internal deformation of the material, and it cannot be applied to general press working other than forging, such as drawing. The improvement of lubricity will be referred to later from a separate and different point of view.

Specific technical ideas/principles, means, and effects of the present invention will be described in detail below. The present invention consists of the following viewpoints: During press working (mainly deep drawing), metal materials (ferrous and non-ferrous; classified by crystal system, BCC, FCC, HCP) processing ( The essence of plastic working / permanent working) is due to the existence of "dislocations", which are nano-level linear defects, and their movement due to external forces and loads, that is, microscopic strain deformation and microscopic twinning deformation. conceived that the former microscopic deformation is the main cause, and connected it to practical means and effects.

Then, the true stress σ ^* required for the movement of dislocations in this microscopic strain deformation and the resulting true strain ε ^* and ε etc.) are roughly represented by the following equations,
σ ^* =( _τ0 ^* +βμb√ρ)/cos θ (10)
ε ^* =(n ₀ Ab)/U (3)
(The meaning of each symbol has already been described), and these relationships are expressed in the plane strain deformation region (in the case of flat-bottom cylindrical drawing , corresponding to the vicinity of the shoulder _radius of the punch) is shown by the following equation (Non-Patent Documents 5, 6):
σ _cr =(2+√3) ¹⁺ⁿ ·[{(1+R)/2}/{(1+2R) ^1/2 /3}] ¹⁺ⁿ ·σ _u (t ₀ /t _f ) (16)
The meaning of the letters in these formulas has already been given.

Furthermore, based on the above, the present invention considers the quantitative relationship between the nano-level microscopic deformation behavior and the macroscopic deformation behavior, and proposes a general mechanical press (with a built-in servo device). , or otherwise equipped with a servomechanism), microvibration is applied to the punch stroke (hereinafter referred to as "microvibration punch stroke").

In the present invention, the metal material is deformed and processed by contact external force from the punch during the forward movement of the punch due to this fine vibration punch stroke, and until it contacts the material during the backward movement of the punch and the next forward movement of the punch. There is no contact between the punch and the material, and the material is not subjected to an external force load, and a time margin is given for a microscopic relaxation phenomenon to occur inside. As a result, the press workability of the metal material is greatly improved, and a single press work process (hereinafter referred to as "single process") that avoids multiple processes enables extremely deep drawing. Can be processed.

Let _Xp be the distance the punch advances and _Xr the distance the punch retracts in the "fine vibration punch stroke" during a single stroke. Therefore, the movement distance ΔX of the material/punch in the deep drawing advancing direction of one micro-vibration punch stroke is X _p −X _r . Further, when the forward speed of the micro-vibration punch stroke is V _p and the backward speed is V _r , V _p =X _p /t and V _r =X _r /t (t: time). And micro-vibration action
0<ΔX<X _p (26)
V _p ≧V _r (27)
should be performed under conditions that simultaneously satisfy
Here, equation (26) is essential for deep drawing to progress under the condition of "vibration motion", and equation (27) equals the backward speed to the forward speed so that the effect of the microvibration motion can be realized. Alternatively, it is slowed down to allow time to facilitate the movement of the dislocations in the next stage.

The meaning of "fine vibration operation" in the present invention is "movement stroke (stroke, ram, slide)" (hereinafter referred to as "stroke ”), as is customary, the punch and the material to be processed are always in contact with each other at a constant speed, and the processing force is applied to move the punch. It is to move while moving forward and backward), that is, while giving "oscillating" action.
The frequency ν (Hz) of the vibration is 3≦ν (Hz)≦10; preferably ν=5 or 6 (28)
It has been found that a pattern of micro-vibration motion, which is a straight linear motion, is particularly suitable. The micro-vibration punch stroke is called (P ₁ ).

Then, we reached the conclusion that it is appropriate to set three basic motion patterns consisting of linear linear motion of this micro-vibration motion and to express them as P _j (j = 1, 2 or 3; see the next paragraph)). did. In addition, as shown in 0057 described later, the "number of steps" when setting different vibration frequencies or micro-vibration patterns (the actual pattern consists of the number of combinations indicated by _{PjCi )} is set to N _i and
It was determined that setting i=1, 2, or 3 is realistic. And even if v changes within the conditions of equation (28) (denoted by v _i ), it does not affect the present invention.

The linear (straight line) stroke (or slide or ram) pattern of the current conventional mechanical servo press machine is "stop, acceleration, maximum speed, deceleration, stop" when moving forward, and "acceleration, maximum speed, deceleration" when moving backward.・Stop”. Practically, the micro-vibration punch stroke of the present invention can be roughly applied to "acceleration/deceleration linear forward/backward uniform/non-uniform vibration" (P ₁ ) (however, there is no time to hold the maximum speed, and " forward velocity V _p >reverse velocity V _r '). Furthermore, a pattern of "constant linear forward/backward constant/non _- uniform vibration" (P2) or "sinusoidal constant angular speed linear forward/reverse constant/non-uniform vibration" ( _P3 ) is more desirable. These micro-vibration patterns P _j (j=1, 2, 3) are indicated by symbols P ₁ , P ₂ , P ₃ in the order described above.

The practical situation of the micro-vibration operation pattern P _j (j=1, 2, 3) is as follows. First, the choice is any appropriate condition represented by _Pj C _i (C is the number of permutation combinations). As described in the previous paragraph, one full pattern of micro-vibration motion of the present invention is as follows:
₃ C ₁ = 3 ways: P ₁ or P ₂ or P ₃ (29a)
₃ C ₂ = 3 ways: (P ₁ +P ₂ ) or (P ₂ +P ₃ ) or (P ₃ +P ₁ ) (29b)
₃ C ₃ = 1 way: P ₁ +P ₂ +P ₃ (29c)

In the seven pattern configurations represented by these _three equations, the ratio of the length of time occupied by P1 _, P2 _, and P3 from the top dead center to the bottom dead center is Ψj ( _j is 1 or 2). or 3), k _1, k _{2, and} k ₃ respectively for equation (29a), l _1, l _{2, and} l ₃ for equation (29b), and The cases are m ₁ , m _{2 and} m ₃ . Then,
k1 ₌ k2= _k3 = ₁ (30a)
l ₁ + l ₂ = l ₂ + l ₃ = l ₃ + l ₁ = 1 (30b)
m1+ _m2 +m3= _{1 (} 30c)
becomes. Ψ is determined experimentally in advance so that the machinability is optimized depending on the material type (in the case of k ₁ , Ψ ₁ =1 automatically).
In the experimental example,
Ψ _k ≡ = 1 (unchanged) (31a) when using a 1 k-system pattern
Ψ _l = 1/2 (31b) when using a 2 l system pattern
When using a 3 m system pattern Ψ _m = 1/3 (31c)
It is desirable to adopt

In addition, it is necessary to determine the number of steps Ni (i=1, 2, 3) of the frequency ν in the seven pattern configurations (i is realistic up to 3 as indicated by 0053). That is, when the frequency is constant between the top dead center and the bottom dead center, the frequency is ν (=ν ₁ ) at N=1 in any of the seven patterns, and the frequency is n times. When changing, N=n and the frequency becomes Σν _i . N is determined experimentally in advance so that the machinability is best for the grade (v _i =v if the frequency is constant over the entire stroke).

FIG. 7 shows a conceptual diagram of a conventional punch stroke and a micro-vibration punch stroke. The figure also shows die height (in this case, the entire stroke), top dead center, bottom dead center, knockout, and so on. In the case of the conventional method, when the punch (stroke) reaches the top dead center at a high speed and contacts the blank and forming starts, the process progresses at an average speed v, and the processing is completed to a predetermined drawing depth. , the punch returns to its initial position by the stroke motion.

On the other hand, in the case of application of micro-vibration, when the punch reaches the top dead center at a high speed and comes into contact with the blank and forming starts, the punch first advances at a speed V _p to a distance X _p , Next, the punch leaves the workpiece (unloaded, non-contact state) and retreats at a speed V _r to a distance X _r (single vibration process (single vibration); as a result, the punch moves a distance ΔX=Xp−X _r ). The punch then moves on to the next vibration process and remains in a non-contact state for a distance up to the material in the previous advance position, and then reaches a contact state and processing progresses. In this way, it finally reaches the bottom dead center while repeating the slight vibration motion of forward and backward movements. FIG. 7 schematically shows the case of V _p =V _r .

The basic factors (elementary process) of the "fine vibration operation" between the top dead center and the bottom dead center are "distance X", "time t" for the punch and "metal (alloy) work material" , “vibration/frequency (number) ν”, and as secondary factors, “the ratio Ψ _j of P _j in combination by _Pj C _i for pattern P _j and P _j of micro-vibration motion and step N _i (Number)”, “Processing temperature T”, “Lubricant L” and the like are added.

In practical application of the present invention based on the above, the following three points should be taken into consideration in terms of industrial application:1. average moving speed of the punch;2. 3. processing amount (drawing through depth); Total processing (extraction) time. I will write about these below. Any of the patterns of micro-vibration operation described in 0054, 0055, and 0056 can be used, and they are regarded as parameters, and there are no particular restrictions on the above elements. Processing temperature and lubricant conditions are also parameters.

1. The movement speed V of the punch stroke with fine vibration is as follows, where _Xi is the distance to an arbitrary position between the top dead center and the bottom dead center:
X _i = ∫ [{(X _p −X _r )/ν}·t] dt (integration range: t = 0 to t _i
(32a)
V=(ΣX _i )/t _f (32b)
Here, t _{i and} t _f are the elapsed time from the middle of the punch stroke to the bottom dead center. Here, V is related to nano-level material internal changes, lubrication, friction, and heat generation, and is also a factor affecting cost through productivity.

2. The working amount (drawing through depth) H _max is an important factor representing the quality of workability in a single pressing step (one pressing step) of the present invention. _Assuming that the punch travel distance from the top dead center is Hi, it can be expressed as follows:
H=∫{(X _p −X _r )ν}dν (integration range: ν=ν ₁ to ν _i ) (33a)
H _max = ∫H dt (integration range: t = 0 to t _f ) (33b)
_tf is the elapsed time from the top dead center to the bottom dead center. Here, H _max is affected by the microscopic and macroscopic conditions due to the action of the micro-vibration described above, thereby making it possible to achieve a drawing depth surpassing that of the conventional method.

3. The draw-through processing time t _max is the reciprocal of the frequency ν _i of the _i -th (X _p −X _r ) _{i = ΔX i} , and the P _j Since the machining is performed with the number of steps N _i through the ratio Ψ _j ,
T _i =Σ[∫{(1/ν)}·dν] _(Ni) (ν=1 to νi; N _i =1 to 3) (34a)
T _max =ΣT _i (i = top dead center to bottom dead center) (34b)
Since Tmax greatly controls production efficiency and is deeply related to product cost and economy, it is an important processing requirement.

Here, I will discuss quantitatively the problem of "contact" and "non-contact" between the punch and the material, which is a feature of the macroscopic behavior of micro-vibration motion. The time Δt during which the punch is out of contact with the material during a single oscillation process for the change (relaxation) of the dislocation state inside the material and the stress/strain field is given by the following equation:
Δt=(X _r /V _r )+(X _r /V _p )=X _r {(1/V _r )+(1/V _p )}(35)
Therefore, if V _p =V _r , then:
Δt= _2Xr / _Vr = _2Xr / _Vp (36)
In general, for frequency ν,
Δt=∫[X _r {(1/V _r )+(1/V _p )}]ν dt (integration range: 0 to t _i )
(37)
In consideration of productivity and mass productivity, the average speed V represented by the formula (32a, b) is
V>v (38)
As much as possible, control conditions and workability are optimized. At this time, it is of course necessary to take into account the _{micro -} vibration patterns _Pj , _{PjCj , Ψj} , and _Ni as _described above. = V _r (“both are variable control”), it is realistic to properly control X _p and X _r and ν _i and N _i , and sufficient effects can be obtained.

Such vibration punch strokes are repeated until the bottom dead center is reached. Strictly speaking, the punch that has reached the bottom dead center returns to the initial position at a high speed without performing the backward movement of _Xr . In FIG. 7, for comparison with the conventional method, the vibration is 5 times (more precisely, 4 and a half times) and the same bottom dead center as the conventional method is reached. Increase the frequency (see next paragraph) to significantly cause the above internal changes. In addition, since the drawing depth is significantly improved as compared with the conventional method, the bottom dead center is different between the two, but they are drawn equally for comparison.

Further, FIG. 8 specifically shows an example of the operation of the micro-vibration punch stroke method. Again, for ease of understanding, the relationship between punch stroke distance and time per frequency is shown. X _r can be small as long as the punch is in a non-contact state with the molding material in the working process. The total time (that is, processing time and cost/economy) to complete deep processing must also be taken into consideration.

The present invention continuously moves from the top dead center to the bottom dead center at the forward speed V _p and the backward speed V _r while imparting micro-vibration motion to the punch stroke (in the case of the conventional method without micro-vibration motion, , the punch (stroke) speed is constant and v). Then, the machining of the blank is advanced by the oscillating motion of the punch stroke, where S _i is the moving distance at an arbitrary position in the machining process and t _i is the moving time. In practice, it is necessary to remove the molded product using a knockout tool. It is applied only during the production period to improve production efficiency.

In the present invention, a further effect can be expected by taking into account the compounding of the pattern of micro-vibration motions of advancing and retracting the punch. That is, normally, the micro-vibration pattern P _j (j=1, 2, or 3) is constant, but as described in equations (29) and (30), vibration combinations _pj C _j and P _j It is desirable to set a plurality of patterns in consideration of the ratio Ψ _j of , and the number of steps N _i of the frequency ν _i . The value of N _i at this time is in the range of N _I =1 to 3 times in consideration of practicality.

The relationship between the drawing depth H and the drawing ratio DR, the limit drawing ratio _LDR and the n value are already shown in the formulas (16), (22), and (23), respectively. and the relationship with the r value. Here, FIG. 9 shows that σ _cr is more dependent on the r value than on the n value (Non-Patent Document 5). In the present invention, the r-value of the material used is already determined, but it is important to suggest that the application of the micro-vibration action suppresses the decrease in the r-value due to processing. FIG. 10 shows the relationship between DR and H (H is represented by _yDp as indicated by 0026; y is a variable) in the drawing of an isotropic material so that the conventional method and the present invention can be roughly compared. The position in the figure is indicated. However, the positions of DR and H (=yD _p ) occupied by each processing method are not determined to be constant values, and "penetration phenomenon (there is an overlapping portion)" exists.

Based on the above description, the present invention limits the range of ν as follows as specific conditions and means for realizing and executing it. The reason for this is that if the following ranges are not met, the relaxation and uniform distribution of the stress field and strain field caused by the sliding movement of dislocations caused by working will not change appropriately for drawing. . Therefore, the range of ν is limited to
3≦ν≦10; preferably ν=5 or 6
Therefore, based on the contents of the above description, the present invention provides specific conditions and means in order to appropriately realize the micro-vibration operation, in which the punch stroke frequency ν satisfies the above equation and the micro-vibration operation pattern P _j (j = 1, 2, 3 single or combined complex processes) are "acceleration/deceleration linear advance/retreat constant/non-uniform vibration" and "constant linear advance/retreat constant/non-uniform motion" as described in 0054. , "sinusoidal constant angular velocity linear forward/reverse constant/non-uniform oscillation" or a combination thereof.

The present invention is characterized by the following conditions for single micro-vibration punch stroke distance (X _p , X _r ) and velocity (V _p , V _r ) and normal uniform machining stroke velocity v. :
0 mm<X _p ≦100 mm; 0 mm<X _r <100 mm; X _p >X _r (39)
_Vp ≧1 mm/sec; _Vr ≦100 mm/sec; _Vp ≧ _Vr (40)
1mm/sec≤V≤500mm/sec (41)
V>v (42)
where V is the average punch stroke velocity in all microvibration motions. When the full stroke of normal continuous machining is represented by H (the distance from the top dead center to the bottom dead center), any single micro-vibration operation will
V _r <V≦V _p (43)
must be controlled to satisfy

In the present invention, it is desirable that the processing temperature T of the material in the micro-vibration operation conforms to the following conditions depending on the crystal system of the metal material, which is a pure metal or an alloy.
Body-centered cubic material: RT≤T≤200°C (44)
Face-centered cubic material: RT≤T≤300°C (45)
Dense hexagonal material: RT≤T≤400°C (46)
Here, "RT" stands for "room temperature". The reason why the upper limit temperature differs depending on the crystal system is that the degree and localization of the accumulation/entanglement of microscopic dislocation groups and the internal stress/strain field due to working generally becomes BCC<FCC<HCP. Mainly, when the types of practically used elements belonging to each crystal system are compared, the degree of difference in atomic density and interatomic force is different.

The metallic materials are very diverse, including pure metals and their alloys. In terms of usage, there are a huge number of fields of application, including advanced scientific fields such as particle physics, accelerators, and medical genetic engineering. In the present invention, with respect to metallic materials, ferrous and non-ferrous materials, or BCC, FCC, and HCP were also classified and examined from the aspect of crystal structure. The reason for this is that in the deep drawing of all metal materials according to the present invention, the essential cause that determines the processing performance is the presence of "dislocations", which are nano-level linear defects, and their dynamic deformation behavior. because they are affected by ferrous/non-ferrous materials, or materials with different crystal systems as mentioned above.

Among them, metal materials that are practically important, frequently used, and difficult to process are listed by crystal system as follows (ferrous and non-ferrous are mixed): High as a BCC material Purity iron, high-carbon steel, high-manganese steel, high-strength steel, surface-treated steel plate, electrical steel plate, niobium, tantalum; FCC-based materials such as austenitic stainless steel, aluminum (alloy), nickel (alloy), copper (alloy) HCP-based materials include magnesium (alloy), titanium (alloy), zinc (alloy), zirconium (alloy), tantalum (alloy), and the like.

These materials have a common deformation behavior of microscopic dislocations, which influences the macroscopic deep drawing performance. Therefore, the formability is improved by applying microvibration motion.

The present invention is further characterized in that microvibration motion is imparted to the punch stroke when performing deep drawing of the above metal materials.

The processing lubricant in the present invention is a liquid oily system. The reason for this is that when micro-vibration is performed, the punch moves up and down while machining progresses in a predetermined direction. This is because it is desirable to use a liquid lubricant with better mobility than a solid film lubricant because a uniform and stable coating is maintained on the surface, and workability deterioration and seizure due to dynamic friction are less likely to occur. At the same time, according to the present invention, since the material and the punch alternately repeat contact and non-contact states, the lubricating liquid is likely to disperse and move, and the lubricating performance is likely to be exhibited and maintained.

As for the performance of an oil-based liquid lubricant, when the "kinematic viscosity" defined by the following equation is represented by Γ,
Γ≡ (absolute viscosity)/(lubricating oil density at processing temperature)
is defined as Here the method of measuring Γ is as follows: obtained by measuring the time it takes a constant volume of sample oil to pass through a capillary using a calibrated capillary viscometer. Considering that Γ has temperature dependence,
In the case of processing at RT ≤ 40 ° C., the following Γ values are used regardless of the type of metal material,
Γ=25 to 100 cSt (less than)
In addition, in the case of processing various metal materials at RT > 40°C,
Γ=over 100 to 800cSt
should be used.

The present invention applies a drawing-out press deep-drawing molded body to which micro-vibration motion is imparted to "restrike processing" (correction processing in which the strain caused by a single pre-forming process is removed by a pressing machine) and / or "ironing". (a press working method in which the clearance (gap) between the punch and the die is made narrower than the wall thickness in order to make the wall thickness of the drawn product uniform).

These processes can be easily performed by drawing a molded product (primary molded product ) has room for post-processing. The reason for this is that severe deep drawing generally results in a large amount of dislocation accumulation, entanglement and non-uniformity, whereas the present invention greatly reduces the degree of dislocation accumulation and entanglement.

This "deformation margin" is represented by the parameter "ζ", and as a result of examining the expression of ζ, it is appropriate to evaluate ζ as a function of the wrinkle holding load F in the drawing process. I found out. That is, assuming that f represents a functional relationship,
ζ=f(F)=f[{F ₀ (φ/φ ₀ )} ^β ] (50)
Here, F ₀ is the wrinkle holding load at the initial stage of drawing, φ and φ ₀ are the volume of the flange during the drawing process and the initial flange volume (area x plate thickness), and β is a "power exponent" determined by the metal material in the drawing process. It is known from the results of basic experiments that the crystal system exhibits the following:
For body-centered cubic metal: 0 < β ≤ 3 (51)
For face-centered cubic metals: 1 ≤ β ≤ 3 (52)
For dense hexagonal metal: 2 ≤ β ≤ 3 (53)

In the present invention, which avoids multiple steps and annealing, supplementary working can be applied as necessary after the press drawing, depending on the final compact structure.
In other words, plastic working (press working) is classified into "primary working", "1.5 working", and "secondary working" according to working modes.
Here, "primary processing" is the main processing of the present invention, and the most important issue is how to improve this with a new method (by press processing in one step) and contribute to industrial application.
In general, it is often the case that the dimensional accuracy, shape fixability, and drawing depth of the primary processed product are not sufficient to meet the specifications from the viewpoint of the single processing limit. It may be processed or ironed. This is called "1.5th processing".
Further, after the primary processing or the 1.5 processing, drilling and burring processing for projecting are often performed. This is based on the customer's design requirements and is called "secondary processing." According to the primary processing, which is the subject of the present invention, the sufficiently large "deformation margin ζ (of the primary processed product)" facilitates the 1.5 and secondary processing. This is not possible with conventional methods.

In general, "secondary processing" includes trimming, hemming, flanging, flanging, protruding, drilling, burring, blowing, caulking, seaming, seaming, caulking, riveting, mouth tightening, and mouth widening. There are various processing forms such as.
In particular, it is extremely difficult to perform these secondary processes after deep drawing (primary process) by the conventional method, and a special treatment method is required. There were issues with productivity and economy.
According to the present invention, "extreme deep drawing" is facilitated and not only the primary workability is improved, but also the secondary workability can be improved, so that a great contribution is made to the final product. You can.

The reason for this is the same as described in 0082. The existence of nano-level dislocations after the primary working is different from that of the conventional method, that is, the microscopic working structure is leveled, and the "deformation margin ζ" is reduced. to improve. This event expands the industrial applicability.

In press drawing, "shape fixability" is important as well as "formability". Generally, the phenomenon related to the shape at the time of design, its accuracy/dimensions, and its accuracy/stable freezeability due to the lapse of time deteriorates as the formability is improved. The reason for this is that more microscopic/macroscopic strain is increased and localized in the compact.

Restriking is a method commonly used for the purpose of removing or reducing distortion in a molded product. is relatively large, it is easy to obtain good results. That is, it is easy to improve the shape and dimension accuracy.

As for the shape fixability of flat-bottomed cylindrical drawing, springback and/or spring-go are likely to occur because the amount of deformation at the bottom of the drawing is small. In order to alleviate this problem to some extent, the motion of the punch is stopped when the punch reaches the bottom dead center during the drawing process. It is known and may be practiced to keep it pressed down for a period of time.

As in the present invention, when performing ultra-deep drawing/ultra-deep drawing processing with improved deep drawability, the strain at the bottom becomes larger than in the conventional method, and the processing force retention at the bottom dead center is essentially as described above. It is difficult to say that this method works well, and the holding time must generally be long.

However, according to the punch load retaining action on the flat bottom portion of the drawn body obtained by the present invention, as shown in FIG. , was found to be close to 0. This result shows that the shape fixability in the ultra-drawing process of the present invention is rather improved, contrary to expectations, although it was commonly expected that it would be difficult.

This is because the dislocations and their strain fields are less-complicated in the material (the microstructure is less complicated than the conventional method and is averaged, and the free energy It can be speculated that the elastic deformation is easily released within the non-contact time between the material and the punch in the process of micro-vibration motion, that is, the activation barrier is relatively low.

The above press (drawing) processing uses the speed and temperature conditions of the punch stroke as parameters, and uses a servo device that enables micro-vibration and speed control for its movement and movement, a press (drawing) processing die, and an appropriate It is preferable to use a liquid lubricant having a kinematic viscosity and a temperature control device for controlling the processing temperature of the metal material by heat conduction from the mold.

By using the micro-vibration press working method for metal materials by punch stroke control as described above, it is possible to solve the conventional problems and manufacture pressed products.

The effects of the present invention can be summarized as follows in comparison with the conventional method. Most of the meanings of the letters in the formulas used here have already been used and explained in previous formulas, with a few exceptions.

(1) It is effective in improving press deep drawability. That is, as a direct index, the amount of processing (depth of drawing) H _max is expressed by the following formula by combining the formulas (33a) and (33b):
H _max =[∫∫{(X _p −X _r )ν}dνdt] _max (54)
And, when compared with the drawing depth h of the conventional method, which is a non-vibration method,
H>h (55)
As a result, the workability (deep drawability) is excellent in terms of the amount of work (depth of drawing).

In addition, in the case of the present invention, the improvement of workability (drawability) is achieved by increasing the critical rupture force σ _cr ^* due to plane strain deformation, which is a rupture risk site, and increasing the rupture resistance in the deformation state diagram. to cause. That is, the critical rupture force σ _cr ^* according to the present invention is as follows when compared with σ _cr according to the conventional method even for the same material (same n value, r value, and plate thickness t):
σ _cr ^* >σ _cr (=f(n, r, t)) (56)
(f represents a functional relationship).

As explained above, the main mechanism is that the external force and load are dispersed, and the collective entanglement of nano-level linear defect dislocations during the machining process and at the end of the machining is relaxed, and at the same time the distribution becomes uniform. be.

(2) The present invention requires a plurality of steps in the conventional method, and even if there is no choice but to insert a heat treatment step in order to soften the work-hardened material between the steps, a single step It can be processed into a molded body through drawing. Therefore, the cost and economic efficiency are greatly improved.

(3) Compared with the present invention in the case of having a shape and dimension that can be processed by a conventional method in a single process, the conventional method requires low-speed processing (change to a hydraulic press instead of a mechanical press, etc.) , the use and cleaning of high-viscosity solid lubricants, or the devising and adopting of warm press processing methods and fusion processing methods, etc., are necessary, resulting in disadvantages. Since the present invention is based on the machining of metal materials by micro-vibration punch stroke control by servoing a mechanical press machine, the average machining speed V, which directly governs productivity/mass production, is significantly shortened, and equation (32a) and (32b) are combined to give:
V=<Σ[∫{(X _p −X _r )/ν}·tdt]>/t _f (57)
This formula is a formula with the parameters of the micro- _vibration operation pattern _Pj , the related item _PjCj , the ratio _Ψj of the selected _Pj , and the number of steps _Ni . Comparing with the average processing speed v, by proper selection of conditions,
V>v (58)
As a result, it is economical in terms of production speed and efficiency.

That is, the processing time t _max per molded product by the conventional method is given by the following, where v is the average processing speed between the top dead center and the bottom dead center, and S is the moving distance of the punch from the top dead center.
t _max =∫(S/v)dv (integral is 0 to S _max ) (59)
becomes. On the other hand, if the processing time (total time including non-contact time) in the case of the present invention is _Tmax , the following equation can be obtained by combining equations (34a) and (35b):
T _max =Σ<Σ[∫{(1/ν)dν}N _i ])> _i (60)
In this case, the control range of the vibration frequency _ν , the number of micro-vibration motion patterns _Pj , the number of combinations thereof _PjCj , and the number of steps _Ni can be varied.
T _max <t _max (61)
is easily possible. Therefore, the present invention is superior to the conventional method in terms of productivity, mass productivity and economy since the time for processing each compact can be shortened.

(4) Even if the type of metal material (component composition and crystal system) varies, the machining control conditions appropriate for the material can be easily selected and implemented by adopting the various conditions variable machining means of the present invention. can be done.

(5) The drawability is superior to that of the conventional method, making it possible to reduce the difficulty (easiness) of forming. That is, in press drawing, the degree of freedom in the type of material and the shape and size of molded bodies and products is increased, and the range of application of press working is expanded.

(6) Improving the deformation margin based on nano-level microscopic behavior facilitates restriking and ironing, as well as facilitates drilling, burring, protruding, flaring, and other secondary workability. .

(7) Since it is a practical processing method that aims at delocalization and uniform distribution of the microstructure (dislocation) of the compact, it is possible to improve the shape freezeability indicated by the shape and thickness dimensional accuracy. can.

FIG. 2 is a diagram two-dimensionally showing a linear defect in a crystal group forming a metal material; A circle indicates a substitutional atom located at a lattice point. Above and below the horizontal dotted line in the central part, the positions and existence states of the atoms at the lattice point are different, and the number of atomic planes perpendicular to the paper surface is different. Dislocations (edge dislocations) corresponding to misalignment are shown two-dimensionally. When a part of a crystal group of a metallic material is represented on a two-dimensional plane, dislocations move horizontally by the scalar distance (approximately the interatomic distance) of the Burgers vector in the part where dislocations exist, resulting in a microscopic It is a figure explaining that sliding deformation occurs. An optical micrograph of the surface of a polycrystalline metal material in which dislocations have caused slip deformation shows streaky traces of slip (slip bands). 2 is an electron micrograph showing the aspect of dislocations inside a polycrystal of a metal material in which dislocations have caused slip deformation. Dislocation entanglement and cross-slip phenomena are observed here and there. To clarify the relationship between metal materials and their plastic working from a microscopic point of view, including nano-level factors, and a macroscopic point of view, including hardware devices, and to develop factors and processes for advancing material processing from a practical point of view. It is a figure which shows a means, an effect, and utility. Dislocation density, crystal rotation/dislocation rearrangement, cross slip, stacking fault (twin) among microscopic internal changes (dislocation state change, etc.) during metal material processing Focusing on the difference in the accompanying machining aspects, it is a conceptual diagram comparing on the time-stroke relationship. It is a figure explaining the concept of the stroke change in the conventional method within the die height range in press work, and the stroke change in micro-vibration operation. Under the condition that the punch descending speed _Vp and the punch ascending speed _Vr are 100 mm/min and Vr=50 mm/min respectively, an example of a micro-vibration operation state consisting of alternating forward and backward punch strokes is modeled. It is a diagram showing. FIG. 4 is a diagram showing analysis results of the critical rupture force σ _cr of a material in plane strain deformation; The relationship between _σcr and the average value R of r values is drawn, and the n value is used as a parameter. It is known that the r value has a greater influence than the n value. Using the derivation formula for the drawing depth H during flat-bottom cylindrical drawing of an isotropic material at room temperature, H (denoted by yD _p ; y is a variable) and DR = D ₀ /D _p (where D ₀ , D _p indicates the diameter of the blank and the diameter of the punch, respectively) (with the thickness reduction rate τ as a parameter). A range of DR is shown in the figure, including the approximate limiting draw ratio (LDR) of the conventional method and the present invention with micro-vibration operation. It is a conceptual diagram for qualitatively explaining the difference between the bottom dead center retention time and the springback amount/springgo amount, that is, the shape freezeability, between the conventional method and the present invention.

As described above, in recent years, there has been a strong demand for improved elasto-plastic workability of metal materials, especially for improved “drawing workability” in press working, which is a typical working method. The reason for this is that it is possible to expect effects such as process reduction, productivity improvement, material yield improvement, work environment improvement, cost reduction, and economic efficiency by converting the method from machine cutting to press processing. .

When press drawing is used, if the drawing depth of the processed product is relatively small or if the shape and dimensions are simple, a single process is sufficient. requires multiple steps (two or more steps). For example, in the case of processing a lithium-ion battery case, the required depth is greater than the shape of a cylinder or square cylinder (more than twice the diameter of a cylindrical case), and 10 to 20 processes are required. Work-hardened materials must be softened by outsourcing multiple times of heat treatment or by in-house production in a heat treatment furnace in which equipment has been invested. As a result, the number of press machines and mold tools increases, disturbing the "flow" of the manufacturing process, requiring a large amount of initial investment and manufacturing time, and causing inconsistencies in mass productivity and economic efficiency.

Therefore, peripheral heating deep drawing method and warm deep drawing method using “heat”, counter hydraulic deep drawing method and hydraulic lubrication deep drawing method using “hydraulic pressure”, friction assisted deep drawing method and wrinkle holding force Means such as controlled deep drawing or fusion pressing have been devised. Although some of them are effectively put into practical use, it is not easy to satisfy the above requirements, and a more advanced press working method has been longed for.

Therefore, as described in FIG. 5, attention was paid to the fact that the macroscopic working of metal materials during press working is attributed to strain deformation/movement of "dislocations", which are nano-level linear defects. Also, in recent years, servo equipment has been installed in press machines, and it has become possible to reduce the energy used in press working and to control stroke speed and motion. Paying attention to such a situation, the invention of the ultra-deep drawing method by the "micro-vibration punch stroke control" of the present invention has been made.

Since the present invention is carried out under an appropriate combination of the following conditions/factors (1) and (2), there are a wide variety of specific processing methods in practice:
(1) Types of metallic materials (ferrous and non-ferrous), crystal systems, dislocation structures, and crystal textures.
(2) Conditions for applying micro-vibration motion (vibration mode = conditions for forward and backward motion of punch stroke), frequency, pattern of micro-vibration motion, combination of patterns, ratio of patterns in combination of patterns, number of steps in pattern・Depth of drawing, processing speed, processing time, processing temperature, kinematic viscosity of oil-based lubricant.
Therefore, as an example, "embodiment mode/tendency" is compared with the conventional method, and illustrated by symbols and explanations. In that case, the metal material and processing conditions are factors, and the results are a summary of the effects on five items of mechanical properties in uniaxial tensile deformation: strength, ductility, n value, r value, and critical breaking strength, and processing performance. and a summary of effects on five items of deep drawability, working anisotropy, 1.5 workability, secondary workability, and shape fixability in deep drawing deformation. Concerning the former material property relationship and the latter deep drawability relationship, specific events are taken up, and the qualitative tendency of performance results compared with the conventional method is shown below.

Table 1 compares the material properties by uniaxial tensile deformation with micro-vibration motion to the properties when normal uniaxial tensile deformation is performed (each average speed V and v is 3 mm / sec) mark the trend. In this case, metal materials are broadly divided into iron-based and non-ferrous-based materials, and these are classified into crystal systems (BCC, FCC, HCP). rice field. In some cases, individual metal species (including pure metals and their alloys) have been characterized.
At the time of these "micro-vibration motions" (expressed as "micro-vibration motions" because they correspond to basic tests in which the deformation motion is slightly different from that during press working), the forward distance X _p = 6 mm and the forward speed V _p = 6 mm/sec. , retraction distance X _r = 0 mm (because of uniaxial tensile deformation, retraction compression motion is impossible), retraction velocity V _r = 0 (stop), and 1 sec of unloading/stopping/relaxation time was given for each X _p . Therefore, as described above, the average tensile velocity V was set to 3 mm/sec, which is the same as v in the case of conventional uniaxial tensile deformation. The vibration frequency ν is 5 Hz, the tensile temperature T is RT and T′≦T<RT, and the pattern of the micro-vibration operation is repetition of “forward→stop (time)”. Note that T' should be changed depending on the type of material, but for the purpose of making a relative comparison here, a constant condition of 100° C. was used. JIS No. 13B was used for the test piece.

これらの単軸引張変形特性は、直接的にはプレス深絞り加工特性を示唆するものとはいえないが、間接的に深絞り加工特性と関連する基本的性質を与えるもので、本発明の微振動動作の付与の効果を端的に把握するうえで、簡便で、肝要かつ基礎的な実証試験である。
表１の結果から以下の諸事項を知ることができる。ここで、そのための評価方法として、微振動動作を伴う加工法による結果と従来法による結果との相対比率を次式のρ_１で定義し、検討することとする：
ρ_１＝（微振動法単軸引張特性）／（従来法単軸引張特性）（６２）

These uniaxial tensile deformation properties cannot be said to directly suggest press deep drawing properties, but indirectly provide basic properties related to deep drawing properties. This is a simple, essential, and basic demonstration test for simply grasping the effect of imparting vibration motion.
From the results of Table 1, the following matters can be known. Here, as an evaluation method for that purpose, the relative ratio between the result of the machining method with micro-vibration operation and the result of the conventional method is defined as ρ ₁ in the following equation and examined:
ρ ₁ = (Micro vibration method uniaxial tensile property) / (Conventional method uniaxial tensile property) (62)

First, "strength properties" are usually indicated by conventional tensile strength TS or flow stress S as data, but calculated true stress σ (= S (1 + λ); see formula (19)) and true strain ε (= ln( 1 +λ); see equation (20)) is more accurate and technical. According to the results of the comparison of the influence of the presence or absence of microvibration (unloading and deformation stop in this case), it depends on the material type and crystal system, but in general, the application of microvibration causes ρ ₁ < 1, indicating a tendency for the strength to decrease. And the extent of it varies slightly depending on the material type and crystal system. This decrease in strength is due to the ease of movement of dislocations and the improvement in mobility compared to the conventional method of unidirectional and continuous tensile deformation only. That is, as described above, dislocation groups (corresponding to a large number of microscopic line defects) that have migrated inside the work plastic body form grain boundaries, impurities, non-metallic inclusions, precipitates, substitutional atoms, and solids. It is presumed that various "inhibitory conditions" such as the stress field of the solubilized atom, the existence of its own pile up or other dislocations (groups) are "relaxed" while the movement of the specimen is stopped, and the movement of dislocations proceeds. be done. The reason why the extent differs depending on the material type and the crystal system is that the above-mentioned inhibition conditions differ. Thermodynamically, the reason why the "relaxation" phenomenon occurs can be said to be based on the "law of entropy increase."

The reduction in macroscopic strength due to such microscopic dislocation behavior is as expected and suggests the possibility of achieving the object of the present invention. This is because an excessive increase in strength tends to locally cause excessive hardening and easily exceed the critical breaking strength σ _cr of the material. That is, the decrease in strength due to the application of microvibration is
σ _cr ^* > σ _cr
It can be said that the relationship of

For strength characteristics, not only TS but also the yield point YS and flow stress S between YS and TS should be considered, but regarding this, the n value definition formula (11) , n=(dσ/dε).

Next, we will focus on “ductility”. Ductility is usually indicated by total elongation EL or elongation rate λ in uniaxial tensile deformation. Uniform elongation EL _u (elongation rate λ _u ) and local elongation EL l (elongation rate λ _l ) are also used if analysis is required. In this case, we have the following relationships: EL≡EL _t =EL _u +EL _l ; λ≡λ _t =λ _u +λ _l ). Here, the lower bracket t represents total. These are "elongation amounts" that represent ductility parameters commonly used in uniaxial tensile tests, and, as in the case of strength, when represented by true strain ε, ε = l n (1 + λ) (Equation (20 )).

The results in Table 1 show that ρ ₁ >1 and the elongation is clearly improved under almost all conditions. For metallic materials, it has been demonstrated that the Ludwick relation of equation (12) holds, σ=Cε ⁿ , so ε is
ε=exp {(σ/C)}/n} (63)
Therefore, if σ is assumed to be constant (C is a constant), the drawing depth can be efficiently deepened in the case of drawing for the same σ, improving press drawing workability It means that there is a possibility.

This means that the so-called microscopic strain will lead to the realization of good macroscopic formability by facilitating the movement of dislocations even if the degree of working is the same according to the present invention. do. Therefore, since it is considered that it acts favorably in actual press drawing, it is clear that it has the possibility of contributing to the improvement of press drawability, which is the target of the present invention.

Judging the results of the "work hardening exponent _n value" from the index ρ1, there is almost no change in the case of BCC metal, and there is a slight increase in the case of FCC metal. Also, no change is seen in the case of the HCP metal. The reason for this is considered to be that in BCC and HCP, since the atomic density of the unit cell is relatively low, dislocation propagation does not increase so much and the degree of work hardening is relatively small. On the other hand, since the FCC unit cell has a higher atomic density than the BCC or HCP, dislocation propagation becomes active, and the dislocation density increases. It is considered that the increase in the n value is caused by

Ultimately, the critical rupture force σ _cr ^* of formula (15) defines the deep drawability, but this functional relationship is again expressed by the following formula (see formula (16)):
σ _cr ^* = f(n, r, σ _u , t) (64)
In this functional relationship, as can be seen from FIG. 9, the n value generally has a slight effect. However, for FCC metals, as noted in 0019, an increase in the n value has a positive effect on workability.

Judging the result of "plastic strain _ratio r value" from the index ρ1, in the case of BCC metal during uniaxial tensile deformation, "suppression/relaxation" of the "decreasing tendency" that generally occurs as the working progresses occurs. On the other hand, FCC and HCP metals show a consistent downward trend (when annealed materials are worked, the slip system is randomized, so the r-value generally decreases). The cause of this BCC is that the above-mentioned atomic density, that is, the dislocation density and the influence of the Schmid factor on the stereo triangle diagram (inverse pole figure) make it easier for crystal rotation to occur during processing, and furthermore, due to the change in free energy inside the material, It is presumed that the micro-vibration operation is involved in the maintenance and generation of the {111} plane strength that is advantageous for drawing, and that this is facilitated. On the other hand, in the case of FCC and HCP, the r-value declines consistently with the progress of processing, according to a microscopic mechanism that conflicts with BCC (for example, the likelihood of randomization of the crystal texture). it is conceivable that.

As in the case of the n value, the drawability is finally determined according to formula (16) (calculation formula for σ _cr ) and formula (54) (calculation formula for drawing depth H _max ). However, the effect of the r value on σ _cr for Eq. (15) (working force P _f >flange resistance P _f ) is much larger than the n value (FIG. 9). Therefore, in the cylindrical deep drawing test, the effect of micro-vibration operation is expected. However, judging from the results of these uniaxial tensile deformation characteristics, it is expected that the BCC metal is more effective in improving formability than the FCC metal and the HCP metal.

Regarding the "critical breaking force σ _cr (actually measured by equibiaxial tensile deformation instead of the above uniaxial tensile deformation)", there is generally a tendency of ρ ₁ >1. This is in line with the fact that the strength characteristics described above generally show a tendency of ρ ₁ >1, and the result is considered to be the basis for suggesting the possibility that the application of microvibration operation will improve workability. It's becoming

As described above, judging from the index ρ1 for _each characteristic value when the "processing temperature" is raised from room temperature to 100° C., the decrease in strength and the increase in ductility (elongation) tend to be emphasized. As the processing progressed, a slight increase in the n value and an increase in the effect of suppressing the reduction of the r value were observed, contrary to the case at room temperature. That is, the increase in processing temperature contributes to the mechanical properties. The reason for this is thought to be that thermal energy is involved in the disappearance of dislocations, the elimination of working strain, and the opening of stress fields, and the initial recovery of the worked structure of the material is brought about. These phenomena all mean that they have an effect of improving deep drawability. That is, it can be said that it was discovered that press working by applying micro-vibration motion of the punch has the effect of promoting and promoting change and improvement of the processed structure inside the material.

Table 2 shows the relative application of micro-vibration motion to the conventional method in flat-bottom cylindrical drawing (no micro-vibration motion of punch; temperature T is room temperature; speed v is 3 mm / sec, which is the same as during uniaxial tensile deformation) The ratio (ρ ₂ ) related to the positive effect is defined in the same manner as the formula (62) in Table 1 (next paragraph), and is shown classified by metal species and metal crystal system. Here, the deep drawing was performed by flat-bottom cylindrical drawing with a diameter of 40 mm, and the lubricant used was a liquid oil having a kinematic viscosity of 245 cSt at 40°C. The micro-vibration punch stroke distance is forward X _p =2.5 mm, backward X _r =0.5 mm, frequency ν=3 Hz, therefore forward speed V _p =7.5 mm/sec, backward speed V _r =1.5 mm/ sec, the average velocity V=3 mm/sec, which is the same as in the conventional method. The micro-vibration motion pattern _Pj was a uniform acceleration/deceleration forward _/ backward motion (P1) until the throttle was released, following the conventional method. The processing temperature T was divided into RT and T'≤T<RT. Although T' should be changed depending on the material type, it is set at 100°C here.

実施例１と同様に、従来法に対して微振動動作を付与したときの加工性の結果とその傾向を評価する評価指標として、次式で示されるρ_２を用いる：
ρ_２＝（微振動動作の付与の結果・傾向）／（従来法の結果・傾向）（６５）
よって、両加工方法による種々の条件における結果と・傾向をρ_２によって微振動動作の付与の可否を判断することができる。

As in Example 1, ρ ₂ given by the following formula is used as an evaluation index for evaluating the result and tendency of workability when microvibration motion is applied to the conventional method:
ρ ₂ = (result/tendency of application of micro-vibration motion)/(result/tendency of conventional method) (65)
Therefore, it is possible to judge whether or not to apply the micro-vibration operation by means of the results and tendencies of ρ2 under various conditions by _both processing methods.

The "deep drawability" comparing the deep drawing method of the present invention and the conventional method is one of the drawing ratio DR normally used in cylindrical deep drawing and the critical drawing ratio LDR indicating the fracture limit. is defined by the following formula,
DR[identical to]( _D0 / _Dp ); LDR[identical to]( _D0 / _Dp ) _max (21)
These are used as indices. where D ₀ and D _p represent the diameter of the circular blank and the diameter of the punch, respectively. Secondly, as described above, the drawing depth H and the fracture limit depth _Hmax are directly used as data. These data are linked by the following relational expression. However, it is assumed that the molded product has no ears or can be ignored (see formula (22)):
H _max =<(D _p /4)[{DR ² /(1−τ)}−1]> _max (22)
Here, τ is the average plate thickness reduction rate.

First, the "drawability" at room temperature will be described. Looking at the workability in terms of LDR and H _max , the drawing method to which the micro-vibration motion is imparted is, without exception, the relative ratio ρ ₂ >>1; significantly larger than that of the conventional method; The effect of imparting is occurring in all metals and alloys. This clearly indicates that the above-described idea content and mechanism are working as expected, since it is considered that the microscopic deformation mechanism is reflected in the macroscopic drawability.
As a related result, regarding the "deformation margin ζ", η≡P _f >Pd (the right side of the symbol ≡ is the flange deformation resistance and the critical breaking resistance) must be satisfied.

This action mechanism has a magnitude relationship depending on processing conditions (material and crystal system). Below, "iron-based materials", which mostly belong to BCC (body-centered cubic) system crystals, will be described from two viewpoints.

First, comparing the results of iron-based and non-ferrous materials, which are roughly classified by type of material, the effect of the invention is greater for iron-based materials. The reason for this is not clear, but empirically, iron elements and their alloys are known to be strong and easy to process, as the materials used historically have changed from stoneware to earthenware to bronze to ironware. It's been in use for years. Inferring this from the nano-level state and behavior, the element number of iron is 26 and the atomic weight is "moderate" among all elements, and the sum of the protons and neutrons that make up the nucleus is an even number. Based on the fact that dislocations are relatively stable so-called "Bose particles", it is speculated that the movement of nano-level dislocations is evenly affected by the interatomic force, and that this is related to the fact that the degree of influence is relatively small ( Going back to nuclear reactions, the same explanation is given for the fact that the abundance ratio of the metallic element "iron" in the universe is abnormally large.) At the same time, the crystal orientation and crystal rotation on the inverse pole figure that define the Schmidt factor cannot be ignored.

Secondly, as described above, most iron-based materials have a BCC crystal structure, which has a relatively low atomic density, easy dislocation movement, and relatively easy slip behavior. As a proof of this, in Table ₂ , the results of niobium and tantalum, which are non-ferrous metals and are BCC-based, have a large ρ2.

In other words, the effect of the crystal system of the material exists when applying the microvibration motion. This fact also matches the ρ ₁ values for the r values in Table 1. In BCC, even if the movement of dislocations is disturbed, the stress field and strain field generated within the punch-material non-contact margin time due to the retreat of the punch exhibit a smaller atomic density than in FCC and HCP. It is considered that the policy is likely to be easily mitigated. Then, the continuation of this relaxation phenomenon by the application of repeated microvibration causes a significant improvement in drawability.

Next, when the processing anisotropy was examined, a positive effect was clearly observed although the degree was not large. In other words, practical metal materials do not exhibit isotropy when processed, but are composed of polycrystalline textures with various planes and orientations. It presents. As a processed product, only the recessed ear can be used, so it is desirable that the depth of drawing up to the recessed ear is deep, in other words, it is isotropic processed so that the difference between the convex ear and the concave ear is as small as possible. Therefore, it can be said that the present invention is a processing method excellent in reducing anisotropy, since the edge difference and concave edge depth are clearly larger than those of the conventional method.
The reason why the "ears" were reduced somewhat by the application of microvibration is that the relaxation phenomenon averages the stress field and strain field, randomizes the microscopic slipping phenomenon, and decreases the r value due to the progress of processing. Even taking into account the negative effect of the ear, the total positive effect, that is, it contributed to the deterioration of the ear.

At the end of the results column in Table 2, the tendency of "shape fixability/dimensional accuracy" is shown.
In the case of flat-bottom cylindrical draw forming, the shape freezeability is
Mainly
・Roundness (Because the generation of ears is usually inevitable to some extent, it is judged from the dimensional changes in the diameter in various directions (angles) at each position from directly below the concave ears to the flat bottom),
· Cylindricity (measure the diameter at each position in the vertical direction of the cylinder of the molded body and judge from the dimensional change tendency in the depth direction), and · Bottom flatness (judgment from the flatness of the flat bottom of the molded body, It is desirable to also measure the change in the continuous part of the cylinder and the flat bottom (equivalent to the shoulder radius of the punch))
Three points are related.

The shape fixability is mainly determined by elastic strain (springback and springgo) during elastic deformation, and is affected by the properties and distribution of microscopic plastic strain of the compact. Although the mutual quantitative relationship is unknown, the results in Table 2 show that ρ ₂ >1 is obtained for all the materials regardless of the degree, so the effect of imparting microvibration motion appears.

Although it is difficult to prove the reason, it can be explained as follows as a hypothesis. That is, since there is a time during which the external force load becomes 0 in the entire processing process including elastic deformation, the state of the internal tissue caused by the load is restored to some extent and returns to its original state, that is, a relaxation phenomenon occurs. As a result, the dislocation structure and the processed texture are more uniform than in the conventional processing method, and the elastic deformation after processing tends to return to its original state. Become. As a result, shape/dimensional accuracy (shape fixability) due to macroscopic strain is improved. Furthermore, since the fact that the deformation margin ζ value is improved makes it possible to work with a margin, the internal stress that tries to return to the original state after processing is reduced, so it can be inferred that the shape fixability is effective.

Furthermore, when looking at the results of the draw-formed product and the 1.5th workability (restrike and ironing), the ρ2 value is higher than ₁ in both cases, and the shape correction ability is improved compared to the conventional method. is doing. This is because the margin of deformation .zeta. shown in the equation (50) is increased by applying the micro-vibration motion as described above.

Similarly, the same results as in the previous paragraph were obtained with regard to secondary workability (drilling and burring protrusion processing). It is clear that the main reason for this is the increase in ζ. This fact is very advantageous for industrial application, is expected to expand the range of application, and is important when considering industrial applicability.

In Example 2 above, if the "working temperature" is raised from RT to 100° C., the deep drawability is further improved. Macroscopically, this has a close relationship with the uniaxial tensile deformation behavior shown in Example 1, i.e., the uniaxial tensile properties, and at the same time facilitates the microscopic movement of dislocations due to external force loading. becomes even more pronounced.

In addition, in any of deep drawing workability, processing anisotropy, shape fixability (dimensional accuracy), 1.5 workability (restrike and ironing), and secondary workability (drilling and burring protrusion workability) Also, it can be seen that the heating treatment at a relatively low temperature of 100°C has a positive effect on the microscopic vibration deep drawability. Therefore, it is desirable to superimpose temperature effects, if desired. It goes without saying that appropriate values for external force load, speed, frequency, advance distance, retreat distance, relaxation time, etc. are related to and associated with various materials.

The technique of the present invention is not limited to deep drawing, which is a typical field of plastic working, as described above, but other techniques that may fall under the category of plastic working, such as extrusion, drawing, and forging. It can also be applied to various fields such as rolling, bending, and bulging.

The specific business targets to which the press working method based on the micro-vibration punch stroke control according to the present invention, which is based on drawing, can actually be applied include the following: houseware goods, kitchen equipment, and cooking. Water heater/water heater field, office building equipment field, food/plumbing (including pipe) field, civil engineering/construction (including thick/medium plate/pipe) field, home appliance (housing, gun parts, etc.) ) field, automobile-related fields (outer panels, membranes, disc brakes, exhaust gas parts, oil pans, and various items around the engine), railroad vehicle fields, cameras, copiers, stationery fields, personal computers, electric and electronic parts, mobile bodies Information equipment and control-related products (including battery cases and sensor cases), vending machines, thermos bottles, and beverage-related fields, medical equipment-related fields (explants and implant products), energy equipment/nuclear fields, advanced science fields ( LNG tanks, nuclear reactors, radioactive material reprocessing equipment, nuclear fusion reactors, heavy ion accelerators, elementary particle accelerators, synchrotron radiation facilities, giant tanks for neutrino detection, gravitational wave detectors), astrophysics, space physics, etc. Niche-related fields, etc.

Claims (13)

When pressing metal materials mainly by drawing,
A micro-vibration press working method for a metal material by means of punch stroke control in which the punch is moved up and down to vibrate the punch stroke,
During the forward movement of the punch in the punch stroke, a working force is generated on the metal material when the punch and the metal material come into contact with each other, and the forming of the metal material progresses.
In the retraction stroke of the punch and the subsequent forward stroke of the punch, when the punch is not in contact with the metal material, nano-level microscopic stress fields and strain fields are generated inside the metal material. The micro-vibration action that alleviates and smoothes the
A micro-vibration press working method for a metal material by punch stroke control, characterized in that it is applied to the punch stroke. Assuming that the forward and backward distances of one punch stroke are X _P and X _{r ,}
The traveling distance during this period is ΔX=X _P −X _r,
Further, if the forward and backward speeds are V _P and V _r , and the forward and reverse times are t _P and t _r ,
The traveling speed during this period is ΔV=ΔX/(tP _{+ tr} )=( _VP · _tP )/( _{tP + tr} )≡( _XP +Xr)/( _tP + _tr ),
In this case, the micro-vibration operation is X _P >X _r , (that is, ΔX>0) and V _P >V _r , (that is, ΔV>0) (the forward direction of the punch is + and the backward direction is −). 2. The micro-vibration press working method for metal materials by punch stroke control according to claim 1, wherein the filling is performed at the same time. In the press working by the punch stroke with the fine vibration operation,
Assuming that the movement distance is X and the subscripts _{P and r denote} forward and backward linear motion, respectively,
X>0; 0 mm<X _P ≦100 mm; 0 mm<X _r ≦50 mm; X _P ≧X _r >0;
When the movement speed is V, both conditions of V _P ≥ 1 mm/sec and V _P ≥ V _r > 0 are satisfied. Micro-vibration press processing method. The range of the frequency ν (Hz) of the micro-vibration operation applied to the punch stroke is 3 ≤ ν ≤ 10,
The micro-vibration pattern of the punch stroke of forward and backward vibration during machining by servo control from the top dead center to the bottom dead center of the punch stroke is as follows.
Conventional acceleration/deceleration linear constant speed forward/backward constant or non-uniform motion (P ₁ ),
Constant speed forward and backward constant or non-uniform motion (P ₂ ),
or sinusoidal constant angular velocity linear forward and backward uniform or non-uniform motion (P ₃ ),
Or _Pj C _j (j=1 or 2 or 3) combining these
The micro-vibration press working method for a metal material by punch stroke control according to any one of claims 1 to 3, characterized in that: The ratio Ψ _j (j = 1 or 2 or 3) of P _j (j = 1 or 2 or 3) in _Pj C _j (j = 1 or 2 or 3) (assuming that ΣΨ _j = 1) can be arbitrarily set,
5. The micro-vibration press working method for a metal material by punch stroke control according to claim 4, wherein the repetition number N _i of said frequency ν (Hz) is 1 to 3 times. Assuming that the average moving speed in the press working by the punch stroke with the fine vibration operation is V _ave , the maximum drawing depth is H _max , and the maximum drawing time is T _max ,
respectively,
V _ave =<Σ[∫{(X _P −X _r )/ν}·t]dt>/t _f
Hmax=[∫∫{(X _P −Xr)·ν}dvdt] _max
T _max =Σ<Σ[∫{(1/ν)dν}] _(Ni) > _i
(here, t _f is the time required for drawing out). The processing temperature T of the metal material in the press working by the punch stroke with the micro-vibrating operation is based on the crystal system of the metal material under the following conditions Body-centered cubic material: room temperature ≤ T ≤ 200 ° C.
Face-centered cubic material: room temperature ≤ T ≤ 300°C
Dense hexagonal material: room temperature ≤ T ≤ 400°C
The micro-vibration press working method for a metal material by punch stroke control according to any one of claims 1 to 6, wherein When the room temperature is 20° C., the metal material has the following crystal system:
Body-centered cubic materials: pure iron, carbon steel, high-strength steel,
Surface-treated steel, ferrite stainless steel,
β-type titanium alloy, tantalum, niobium Face-centered cubic materials: austenitic stainless steel, aluminum alloy
Copper alloy Close-packed hexagonal material: Magnesium alloy/α-titanium alloy. Depending on the processing temperature T,
kinematic viscosity Γ is
When T≤40°C: Γ = 25 to 100cSt
When T>40°C: Γ = over 80 ~ 800cSt
9. The micro-vibration press working method for a metal material by punch stroke control according to claim 7 or 8, wherein each lubricant is used. It is characterized by using a servo device that imparts the fine vibration motion to the vertical movement of the punch stroke, and a temperature control device that controls the processing temperature of the die material by heat conduction from a die tool for press drawing. The micro-vibration press working method for a metal material by punch stroke control according to any one of claims 1 to 9. The molded body that has undergone the micro-vibration press working method for a metal material by punch stroke control according to any one of claims 7 to 9,
The processing temperature T is
When T = room temperature: in the conventional method,
When T = above room temperature to 200°C: in the warm press method,
A micro-vibration press working method for a metal material by punch stroke control, characterized by applying restrike processing or ironing processing. Any one of claims 7 to 9 or the molded body that has undergone the micro-vibration press working method for metal materials by punch stroke control according to claim 11,
The processing temperature T is
When T = room temperature: in the conventional method,
When T = above room temperature to 200°C: in the warm press method,
A micro-vibration press working method for a metal material by punch stroke control, characterized by performing drilling or burring protrusion processing. Press working in a single step that avoids annealing heat treatment and cutting by a machining center by using the micro-vibration press working method for metal materials by punch stroke control according to any one of claims 1 to 12. A method for manufacturing a pressed product, comprising manufacturing a product.

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