JP4430739B2 - Casting method for casting products and press device used in the casting method - Google Patents

Description

  The present invention relates to a casting method of a cast product and a press device used in the casting method. More specifically, a casting product casting method for casting a cast product by pressing the upper mold so as to overlap the lower mold into which a predetermined amount of molten metal necessary for casting the cast product is injected, and pressing The present invention relates to a press apparatus used in the casting method.

  Conventionally, as a method of increasing the yield of castings, a method of casting by directly pressing the upper and lower molds after directly pouring the lower mold without a runner has been adopted. In such a casting manufacturing method, the following process is employed. That is, a lower mold having only a cavity required for casting product casting, which is a main mold formed by various mold making methods and does not have a cavity (runner or the like) necessary to achieve a casting plan, Cavity for casting product casting can be defined with the cavity of the lower mold, which is a main mold made by various mold making methods and does not have a cavity (runner, etc.) necessary to achieve the casting plan. Casting with an upper mold having a protruding portion, and after injecting an amount of molten metal necessary for casting only the casting product into the cavity of the lower mold, A casting method for pressing the upper mold so as to overlap the lower mold so as to define a cavity necessary for casting only the casting product by causing the protruding portion to enter the cavity of the molten metal injection ( Sand type press casting process) has been proposed (see Patent Document 1).

JP 2005-52871 A

  However, in the casting method, since the molten metal is supplied to the lower mold and then the upper mold is overlaid and pressed to form the product shape, in the pressing process, when the press speed is high, the molten metal is a sand mold. As a result of entering into the gap between the sand grains on the surface and solidifying as it is, the casting surface becomes rough and rough. This is called an insertion defect, and is generated when the flow rate of the molten metal is slower than the high press speed, and the molten metal in the mold is increased in pressure. Further, when the pressing speed is slow, internal defects may occur due to the generation of an oxide film, or the molten metal may solidify in the mold, and the mold shape may collapse if pressed as it is. As a result, conventionally, in the press process, the occurrence of product defects due to the press speed has become a problem, so that an excessive pressure is not applied to the molten metal and the press speed for realizing a quick press process is not required. Establishment of control is desired.

  Therefore, in view of the above circumstances, the present invention provides a high quality casting product by controlling the pressing speed of the upper mold in the pressing process when pressing the upper mold on the lower mold as a production condition of the casting. It is an object of the present invention to provide a casting method of a cast product and a press apparatus used in the casting method.

  The casting product casting method of the present invention includes a lower mold into which a predetermined amount of molten metal necessary for casting the cast product is injected, and pressing the mold so as to overlap the lower mold. A casting method for casting a cast product using a mold composed of an upper mold that defines a cavity for casting a mold, using pressure estimation means for molten metal in the mold based on shape data of upper and lower molds The press speed is controlled by estimating the pressure applied to the molten metal in the pressing process.

  The casting press device of the present invention is a press device used in the casting method of a cast product, and includes a movable frame, an elevating means provided on the movable frame, and a guide rod for guiding the elevating and lowering means. And a detecting means for detecting the state of the upper mold, and a pressure estimating means for the molten metal, controlling the operation of the movable frame, the lifting means and the fixing means, and based on the detection data of the detecting means And a control means for controlling the operation of the elevating means.

According to the present invention, it is possible to suppress an excessive increase in the molten metal pressure by switching the pressing speed before the molten metal pressure in the mold applied to the molten metal during pressing in the pressing process using the molten metal pressure estimation means becomes excessive pressure. Therefore, it is possible to suppress defects generated in the cast product and obtain a high-quality cast product.
Also, even if there is a variation in the liquid level position of the molten metal poured into the lower mold, the pressure fluctuation of the molten metal in the mold is estimated in advance, and the press speed is changed so that the desired molten metal pressure is obtained. High quality casting products can be obtained.

  Further, by detecting that the upper mold has contacted the molten metal in the lower mold from the reaction force value generated in the upper mold measured by the detecting means, and determining the timing for switching the lowering speed of the upper mold to the low speed pattern, Even when the amount of pouring varies and the liquid level of the molten metal varies, it is possible to perform a pressing process in which the upper mold is lowered at high speed.

When there is no means for detecting the reaction force value from the molten metal generated in the upper mold during pressing, the press speed switching position for suppressing the pressure rise can be determined by estimating the maximum amount of pouring in advance. The maximum pouring amount is a volume obtained by adding a positive error volume for the product portion cavity depending on the pouring accuracy to the product portion volume.
This application is based on Japanese Patent Application No. 2007-115456 filed on April 25, 2007 in Japan, the contents of which form part of the present application.
The present invention will also be more fully understood from the following detailed description. However, the detailed description and specific examples are preferred embodiments of the present invention and are described for illustrative purposes only. This is because various changes and modifications will be apparent to those skilled in the art from this detailed description.
The applicant does not intend to contribute any of the described embodiments to the public, and the disclosed modifications and alternatives that may not be included within the scope of the claims are equivalent. Part of the invention under discussion.
In this specification or in the claims, the use of nouns and similar directives should be interpreted to include both the singular and the plural unless specifically stated otherwise or clearly denied by context. The use of any examples or exemplary terms provided herein (eg, “etc.”) is merely intended to facilitate the description of the invention and is not specifically recited in the claims. .

According to the present invention, a predetermined amount of molten metal necessary for casting a cast product is injected, for example, a lower mold having a concave portion exhibiting a part of a product contour shape, and overlapping the lower mold, It is possible to use a mold that defines a cavity for casting a cast product, for example, an upper mold having a bulging portion that exhibits a part of the product contour shape. The present invention also uses the molten metal pressure estimation means based on the shape information of the upper and lower molds to estimate the pressure in the mold applied to the molten metal during pressing in the pressing step. In order to prevent the pressure in the mold applied to the molten metal during pressing in the pressing process from becoming excessive, the upper mold position (speed switching position) that reaches a predetermined set pressure is predicted and the speed switching is performed. The press speed of the upper mold is switched at the position. As the upper mold, an upper mold having a molten metal raised portion (cavity) in a predetermined portion, for example, a fitting portion located in the vicinity of the outer periphery of the bulging portion, can be used.
The lower mold and the upper mold can be appropriately molded using various mold molding methods such as a green mold, a shell mold, a cold box mold, and a self-hardening mold. In the present invention, the core may be disposed in the upper mold or the lower mold. The mold of the present invention includes a porous mold. Furthermore, the mold molding method is not limited to squeeze, blow squeeze, air pressure molding method, or a combination thereof, but can also be a molding method such as cutting or pouring. In addition, the said casting product removed casting methods, such as pouring systems, such as pouring gates, raising, and degassing, from the general casting raw material taken out from the casting_mold | template after an open frame, for example, pouring gates, runners, and weirs. It is a thing that is attached to the machine as a final part or sold separately, such as a circular brake drum or a square case. The molten metal refers to a material in which iron or non-ferrous metal is dissolved and can be injected into the lower mold.

Embodiment 1

Hereinafter, a casting method of a casting product of the present invention and a press device used in the casting method will be described with reference to the accompanying drawings. As shown in FIG. 1, the casting press apparatus 1 used in Embodiment 1 of the present invention is arranged to face a ladle tilting type pouring machine 2 along a molding line. The pressing device 1 includes a movable frame 3 connected to a traveling carriage (not shown) that reciprocates in the lateral direction (left and right direction in FIG. 1), elevating means 4 provided on the movable frame 3, The mold pressing plate 6 connected to the tip 5a of the rod 5 of the lifting means 4, the guide rod 7 standing on the mold pressing plate 6, and the upper mold F1 are opposed to each other among the four sides of the mold pressing plate 6. For example, four fixing means 8 supported from two sides, a detection means 10 for detecting a reaction force value applied to the upper mold by the pressure of the molten metal 9, and a control means 11 are provided.
A raised portion 14 of the molten metal 9 is formed in the fitting portion 13 located in the vicinity of the outer periphery of the bulging portion 12 of the upper mold F1. The number of the raised portions 14 is determined by the amount of surplus molten metal and the shape of the raised portion, and may be at least one, but in the first embodiment, in the circumferential direction of the fitting portion 13. Twelve are formed at equal intervals.

The lifting / lowering means 4 is not particularly limited in the present invention as long as the rod 5 can be lifted and lowered by an electric type, a hydraulic type or a pneumatic type. In the first embodiment, the position and speed of the rod 5 are determined. Electric servo cylinders that can be controlled with high precision are used. This electric servo cylinder incorporates a screw mechanism, a drive motor, a rotary encoder as a position detector, and the like. In place of the electric servo cylinder capable of controlling the position and speed of the rod 5, an electric servo cylinder capable of controlling only the speed and a linear scale are used in combination to detect the position of the upper mold and control the positioning. You can also.
The fixing means 8 is not particularly limited as long as it can support the upper mold F1 on the mold pressure plate 6. For example, a driving mechanism such as an air cylinder and the operation of the driving mechanism are supported. And a clamp member that rotates or expands and contracts. Alternatively, a support structure using an electromagnetic force or a support structure using an attractive force can be used.
The detecting means 10 is not particularly limited as long as it has a function of detecting a reaction force value applied to the upper mold by the pressure of the molten metal 9 during pressing. Can be selected. In the first embodiment, since an electric servo cylinder is used as the lifting / lowering means 4, a load cell provided at the rod tip 5 a of the lifting / lowering means 4 is selected.
Further, the control means 11 includes a driving circuit for reciprocating movement of the traveling carriage, a driving circuit for controlling the ascending / descending speed of the lifting / lowering means 4, a driving circuit for controlling stop, a driving circuit for the fixing means 8, and these driving circuits It is comprised from the memory etc. which memorize | stores the pressure estimation means of the molten metal etc. which are previously input and the molten metal pressure | voltage control.
Note that the molten metal pressure estimation means includes shape data of the upper and lower molds, for example, an inner diameter dimension and a height dimension, and changes in the pressure of the molten metal based on positional information where the upper mold contacts the liquid surface position of the molten metal. And a speed switching position for switching the lowering speed of the upper mold so that the pressure does not exceed a predetermined upper limit pressure is calculated. The predetermined upper limit pressure means a preset pressure at a level that does not cause defects such as insertion defects in the cast product.

  In order to realize a rapid pressing process in the casting method, it is required to increase the pressing speed. However, the high-speed pressing causes an abrupt pressure change in the mold and causes an excessive pressure to be generated. May lead to defects. Therefore, in the present embodiment, the press speed is controlled in consideration of suppression of excessive pressure by the molten metal pressure estimation means. Here, it is necessary to measure the actual molten metal pressure in the mold, but it is difficult to use a contact-type pressure sensor for a high-temperature molten metal of about 1400 ° C., so that the load cell acts on the upper mold. By measuring the reaction force value (melt reaction force value at the time of pressing), a press speed pattern that descends quickly is set. FIG. 2 shows the configuration of a system for controlling the lowering speed of the upper mold in the press apparatus. Upper mold lowering position (vertical direction position) data, which is sequentially measured by an encoder attached to the electric servo cylinder, is processed by a programmable sequencer, which is an arithmetic processing unit, and an upper mold position command is transmitted. Position feedback control by a PID controller is configured to drive the electric servo cylinder and control the position of the upper mold based on the position command of the upper mold.

First, in the first embodiment, the melt pressure in the mold when the upper and lower molds are pressed is analyzed using a Computational Fluid Dynamics (CFD) model. As computational fluid dynamics software, FLOW-3D (manufactured by Flow Science) is used. This software is used in a wide range of fields such as flow analysis during discharge in dam design and dynamic characteristics analysis in continuous casting. Since FLOW-3D has a function of reproducing a moving obstacle to the fluid, it is possible to analyze a filling behavior during a press operation.
In addition, a molten metal press experiment is performed using an actual machine, and the molten metal pressure in the mold is verified by CFD analysis against the reaction force value from the load cell at that time. In the verification, the outline of the pressing process is shown in FIG. In FIG.
M _U : Mass of upper mold M _G : Mass of guide rod M _M : Weight of molten metal (kg)
ρ: Density of molten metal (kg / m ³ )
γ: Molten metal viscosity (Pa · s)
A: Surface area of the lower surface of the upper mold (m ² )
Z (t): Upper mold position (distance) (m)
h (t): Liquid surface position of the molten metal (deviation between the lower end surface of the upper mold and the surface of the molten metal) (m)
It is.
Table 1 shows the conditions of the verification experiment.

そして、検証例として、表１の条件における、プレス実験でのロードセルの反力データと、ＣＦＤ解析での圧力値を比較する。ここで、ＣＦＤ解析による数値計算のサンプリング周期は０．０１（ｓ）であり、ＣＦＤ解析における分割メッシュブロックは２（ｍｍ）幅の立方体としている。ＣＦＤ解析で得られた圧力Ｐ_Ｃ（Ｐａ）とロードセルで計測される反力値Ｆ_ｕ（Ｎ）との関係は、つぎの式（１）で示される。

As a verification example, the reaction force data of the load cell in the press experiment under the conditions shown in Table 1 is compared with the pressure value in the CFD analysis. Here, the sampling period of the numerical calculation by CFD analysis is 0.01 (s), and the divided mesh block in the CFD analysis is a cube having a width of 2 (mm). The relationship between the pressure P _C (Pa) obtained by CFD analysis and the reaction force value F _u (N) measured by the load cell is expressed by the following equation (1).

比較結果を図４に示す。図４において、破線がプレス実験の結果であり、実線がＣＦＤ解析によるシミュレーション結果である。プレス実験での応答とＣＦＤ解析での応答について、勾配が急激に上昇するタイミング、すなわち、揚がり部に溶湯が進入する時刻（２．０２（ｓ））がほとんど一致している。しかし、１．９（ｓ）付近から、解析値に対してロードセル値が５０〜８０（Ｎ）程度大きい。原因として、上下鋳型を正確に位置合わせするために設けているはめ合いピン２１が、嵌合部２２に接触することに因ると考えられる。また、終盤での反力値の増加量は大きく異なっている。これは、上鋳型が下鋳型に接触することによって上鋳型の重量分の負荷が軽減されるからである。
これらのことから、ＣＦＤ解析から得られた反力値は、プレス実験の結果とほぼ一致していることがわかる。したがって、ＣＦＤ解析による溶湯の圧力値が実際の鋳型内の溶湯圧力を再現していることがわかる。

The comparison results are shown in FIG. In FIG. 4, the broken line is the result of the press experiment, and the solid line is the simulation result by CFD analysis. Regarding the response in the press experiment and the response in the CFD analysis, the timing at which the gradient abruptly rises, that is, the time (2.02 (s)) at which the molten metal enters the raised portion is almost the same. However, from around 1.9 (s), the load cell value is about 50 to 80 (N) greater than the analysis value. The cause is considered to be that the fitting pin 21 provided for accurately aligning the upper and lower molds comes into contact with the fitting portion 22. Further, the amount of increase in the reaction force value at the end is greatly different. This is because the load corresponding to the weight of the upper mold is reduced by the upper mold coming into contact with the lower mold.
From these facts, it can be seen that the reaction force value obtained from the CFD analysis almost coincides with the result of the press experiment. Therefore, it can be seen that the molten metal pressure value by CFD analysis reproduces the actual molten metal pressure in the mold.

The molten metal pressure value in the CFD analysis was confirmed to be reliable by the result of the press experiment, but because the CFD analysis is an off-line calculation, it is caused by variations in the initial liquid level position of the actual pouring amount. It is impossible to predict the behavior change of the molten metal pressure. However, in the pressing process, it is possible to estimate the pressure fluctuation of the molten metal using the reaction force value data of the load cell.
That is, it is possible to specify the time when the tip of the upper mold contacts the molten metal from the data of the reaction force value of the load cell, and using this time and the press position data by the encoder, the initial liquid surface position of the poured molten metal Therefore, the pressure fluctuation of the molten metal relative to the press speed can be estimated from the estimated initial liquid surface position of the molten metal.
By estimating the pressure fluctuation with respect to the pressing speed, it is possible to control the pressing speed for suppressing an excessive pressure at which insertion defects occur.

Therefore, from these facts, a melt pressure estimating means is constructed in order to determine the press speed. First, as shown in FIG. 3, the upper mold shape of the mold used is a shape having a small convex at the convex tip of the surface area A. It has been found that the insertion defect occurs outside the lower surface of the convex portion having the surface area A. Using a simple mold that excludes the curved portion, the inclined portion, and the draft portion in the original mold shape, the pressure change in the defect occurrence portion is examined. The shape of the simple mold used in this pressure estimation means is shown in FIG. In FIG. 5, b _{1 to} b ₂ and d _{1 to} d ₄ indicate the shape information of the height and diameter of each mold. P _j (j = 1, 2) is a place where defects are likely to occur. z (t) is the downward displacement of the upper mold from the position at the moment when the lowermost part of the upper mold descending comes into contact with the liquid surface after pouring. h ₀ is the initial molten metal height (liquid level position). H (t) indicates the maximum height of the liquid from the lowermost part of the upper mold, which directly represents the head pressure applied to the point Pj. As the press speed increases, dynamic pressure expressing the difficulty of flow is added.
Next, a molten metal pressure model is considered based on an ideal fluid that assumes incompressibility and non-viscosity based on dimensional information of the mold shape, and the pressure fluctuation of the molten metal during pressing is predicted. First, the tip of the molten metal flowing upward, that is, from the dynamic pressure due to the flow velocity at the maximum liquid level position height portion it is contemplated that also participate in P _j point, the pressure P _b in the P _j point, static Dynamic pressure is added to the pressure, and is expressed by the following equation (2).

ここで、ｇ（ｍ／ｓ^２）は重力加速度を示す。図５より、溶湯の上昇液面位置は流動路が異なる、ｃａｓｅ１：ｄ_２−ｄ_１間、ｃａｓｅ２：ｄ_３−ｄ_１間、およびｃａｓｅ３：ｄ_４の３つの流動パターンを持つことがわかる。それぞれの液面位置の変化について、溶湯が非圧縮性流体であると仮定すると、容易につぎの式（４）を得ることができる。ここで、揚がり部の本数ｎが１２本であるため、揚がり部の数ｎは１２である。

Here, g (m / s ² ) represents the gravitational acceleration. From FIG. 5, it can be seen that the rising liquid surface position of the molten metal has three flow patterns of different flow paths: between case 1: d ₂ -d _1, between case ₂ : d ₃ -d ₁ , and case 3: d ₄ . Assuming that the molten metal is an incompressible fluid for each change in the liquid level position, the following equation (4) can be easily obtained. Here, since the number n of the raised portions is 12, the number n of the raised portions is 12.

また、ｈ_ｓｗｌ、ｂ_１は、ｈ（ｔ）によるｃａｓｅ１→ｃａｓｅ２、ｃａｓｅ２→ｃａｓｅ３の切り替え条件であり、ｈ_ｓｗｌはつぎの式（５）のようになる。

Further, h _swl and b ₁ are switching conditions of case 1 → case 2 and case 2 → case 3 according to h (t), and h _swl is _{expressed by} the following equation (5).

前記液面位置ｈ（ｔ）がｈ_ｓｗｌと等しくなったとき、式（４）はｃａｓｅ１からｃａｓｅ２に切替えられる。液面位置ｈ（ｔ）がｂ_１に達したとき、式（４）はｃａｓｅ２からｃａｓｅ３へ切り替えられる。以上のように、プレス速度に起因する溶湯の圧力応答は、初期溶湯高さ（充填量）と鋳型形状によって決定されることになる。

When the liquid surface position h (t) becomes equal to h _swl , Expression (4) is switched from case 1 to case 2. When the liquid level position h (t) reaches b ₁ , the equation (4) is switched from case 2 to case 3. As described above, the pressure response of the molten metal resulting from the pressing speed is determined by the initial molten metal height (filling amount) and the mold shape.

Next, the pressure estimation means of the molten metal in the mold is verified for the fluid behavior analysis during pressing by FLOW-3D of CFD analysis software.
FIG. 6 shows a graph comparing the fluid level position h (t) obtained by assuming that the molten metal is an ideal fluid based on the simple mold and the fluid level position h (t) as a result of CFD analysis. In FIG. 6, the broken line indicates the estimation result of the fluid level position based on the molten metal pressure estimation means, and the solid line indicates the result of CFD analysis. As a result of the CFD analysis, the measurement point M _{h (t) i} in FIG. 5 is measured. The liquid level position for the four raised portions is measured, and h (t) is calculated. Here, the press speed is set to 5 (mm / s). In the response by the CFD analysis, the molten metal is compressed by the influence of gravity, and the fluid level position is low at the end of the process.

Next, comparative evaluation is performed on the fluctuation of the pressure value of the molten metal at the insertion defect occurrence portion. In the analysis here, the simple template described above is used.
The CFD analysis shows only the pressure variation at the _{P 2} portion in FIG. Here, it was confirmed that there is no difference in change in P ₁ and P _2. In the case of the press speed to 5 (mm / s) and 30 (mm / s), the pressure fluctuation of the molten metal in the _{P 2} moieties are shown in FIGS. In FIGS. 7 and 8, the broken line indicates the calculation result by the molten metal pressure estimation means using the equation (2), and the solid line indicates the result of the CFD analysis. Assuming that the molten metal is an ideal fluid, it can be seen that the pressure response calculated by the pressure estimation means of the molten metal and the pressure response obtained as a result of the CFD analysis are in good agreement. From this, it can be seen that the pressure value calculated by the molten metal pressure estimation means using Equation (2) is appropriate.
It has already been confirmed that an insertion defect that is a problem in the pressing process occurs at a pressing speed of 80 (mm / s) or more. At higher press speeds, when the molten metal flows through the frying part, an excessive pressure that causes a defect is generated. Therefore, the pressing speed is controlled so that the pressing speed is switched when the molten metal enters the frying part. . FIG. 9 shows a flowchart of sequence speed control for pressing speed switching. The speed switching position at which the pressing speed is switched is calculated using the above formulas (4) and (5).

Next, an example of pressure suppression verification in a molten metal pressure suppression simulation by CFD analysis is shown. First, the initial press speed as the first speed is set to 100 (mm / s), and the press speed is switched to the low speed of 10 (mm / s) as the second speed at the entry position to the lifting portion. At this time, the initial liquid level position (pouring amount) is set to 19.2 (mm). In this case, the speed is changed by the upper die press (upper die) after the tip of the upper die contacts the surface of the molten metal. This is performed at a position moved 29.90 (mm) downward in the vertical direction. Further, the molten metal temperature in the mold is assumed to be 1300 degrees.
The result of the molten metal pressure suppression simulation is shown in FIG. The upper part in FIG. 10 shows the lowering speed (pressing speed) of the upper mold, and the lower part shows the molten metal pressure in the mold. The lower solid line in FIG. 10 shows the pressure response of the molten metal when the pressing speed is switched, and the broken line shows the pressure response of the molten metal when the pressing speed is not switched. It can be seen that the pressure fluctuation is much smaller in the case of the case than in the case where the press speed is not switched. At a time of about 1.17 (s) (liquid level detection position), the molten metal pressure rises by colliding with the upper mold and the surface of the molten metal. From this, when the press speed was not switched and the pressurization was performed at a constant press speed of 100 (mm / s), the excessive pressure generated when the molten metal flowed through the raised portion increased to 304080 (Pa). From FIG. 10, it can be seen that the rapid increase in the melt pressure can be suppressed by switching the press speed to be small at a position immediately before the melt enters the frying portion. In FIG. 10, the molten metal pressure at the liquid level detection position and the symbol S exceeds the set pressure 5 (KPa), which is an error caused by calculation.
FIG. 11 shows a block diagram of press speed control in the first embodiment. In FIG. 11, R _Fout is the reaction force value of the load cell. Here, Z _in is the target value of the upper mold position, Z _out is the position (encoder value) of the upper mold, and M is the sum of the mass of the upper mold and the mass of the guide rod. W ₁ and W ₂ mean conversion expressed by the following equation (6).

  In the first embodiment, by using the melt pressure estimation means in the mold, the press speed can be switched from the predetermined first speed to the second speed at the set position before the melt pressure in the mold becomes excessive. This makes it possible to perform the pressing process at a high speed, suppress the occurrence of insertion defects, and obtain a high-quality casting product.

Embodiment 2

Next, as a second embodiment according to the present invention, a molten metal pressure estimating means that switches the lowering speed of the upper mold using the relationship between the lowering speed of the upper mold and the molten metal pressure in the mold will be described.
Consider a case where the mold shape shown in FIG. 12 is press-molded. Here, h (t) and Z (t) in FIG. 5 are replaced with e _h (t) and Z _h (t). As a result, the melt pressure P _b (t) at the point P ₁ near the top end surface of the upper mold at the time of press molding is expressed by the following equation (7) using the deviation e _h (t) between the lower end surface of the upper mold and the liquid surface: ).

ｅ_ｈ（ｔ）＝ｆ（Ｚ（ｔ），ｈ_０）であることから、式（７）から、プレス成形前の溶湯高さｈ_０と上鋳型位置Ｚ（ｔ）から鋳型内の溶湯圧力を得ることができる。
また、ロードセルによる反力値Ｆ_ｕと溶湯圧力Ｐ_ｂの関係は、つぎの式（８）となる。

Since e _h (t) = f (Z (t), h ₀ ), from formula (7), the melt pressure h ₀ before press molding and the melt pressure in the mold from the upper mold position Z (t) Can be obtained.
The relationship between reaction force value F _u and the melt pressure P _b by the load cell, the following equation (8).

ここで、Ａは，溶湯中の上鋳型水平面積（ｍ^２）を示す。ｍは上鋳型の段差数を示し、Ａ_ｉはｉ番目の段差における水平面積（ｍ^２）、Ｐ_ｉはｉ番目の段差付近の圧力（Ｐａ）となる。図１２において、段差数はｍ＝２となり、面積Ａ_ｉと圧力Ｐ_ｉはそれぞれ式（９）と式（１０）となる。

Here, A indicates the upper mold horizontal area (m ² ) in the molten metal. m represents the number of steps of the upper mold, A _i represents the horizontal area (m ² ) at the i-th step, and P _i represents the pressure (Pa) near the i-th step. In FIG. 12, the number of steps is m = 2, and the area A _i and the pressure P _i are expressed by the equations (9) and (10), respectively.

Formula 1

Formula 2

Formula 3

Formula 4

Formula 5

Equation 6

Equation 7

Equation 8

これより、プレス成形時における上鋳型の降下速度は式（１４）、（１５）および式（１８）を用いて、つぎの式（１９）に演算される。

From this, the lowering speed of the upper mold at the time of press molding is calculated into the following equation (19) using the equations (14), (15) and (18).

この式（１９）を用いた上鋳型の降下速度を制御するフローチャートを図１３に示す。

FIG. 13 shows a flowchart for controlling the lowering speed of the upper mold using the equation (19).

Equation 9

Embodiment 3

Next, a third embodiment according to the present invention will be described. FIG. 14 shows a flowchart for switching the lowering speed of the upper mold according to the third embodiment. According to this flowchart, first, as initial information, the first speed (V1) that is the lowering speed of the upper mold, the second speed (V2) that is the lowering speed of the upper mold, the shape data of the upper and lower molds, and the lower surface of the upper mold The position of the upper mold just before contacting the molten metal surface (H), the allowable maximum pressure (set pressure) of the molten metal that does not cause insertion (P1), the position of the upper mold when the press is completed, and the mold will not be deformed. The position of the mold, the pressing force (load cell reaction force value) (P2) of the upper mold that does not cause mold deformation of the mold, and the like are input (step S1). Next, after starting the pressing process, the upper mold is lowered at the first speed V1 (steps S2 and S3). Then, after detecting that the upper mold has reached the predetermined position (H), the speed is switched and the upper mold is lowered at the second speed V2 (step S4). Next, when it is detected that the tip of the upper mold is in contact with the liquid surface of the molten metal (step S5), data on the position where the upper mold is in contact with the liquid surface using the pressure estimation means of the molten metal and shape data of the upper and lower molds. In addition, the pressure fluctuation of the molten metal in the mold is estimated. At this time, based on the estimation result of the pressure fluctuation, the position Z1 of the upper mold that reaches the set pressure P1 is calculated. Next, after detecting that the upper mold has reached the position Z1, the speed of the upper mold is switched, and the upper mold is lowered at the third speed V3 (step S6). Then, after detecting a predetermined pressure P2 (load cell reaction force value), the lowering of the upper mold is stopped at the press completion position, and a series of pressing processes is completed (steps S7 to S9). The second and third speeds may be calculated using the molten metal pressure estimation means in the second embodiment.
In the present third embodiment, the molten metal 9 that has been poured into the lower mold F2 is solidified quickly by using the molten metal pressure estimating means in the second or third embodiment before the upper mold F1 is solidified. Since the shape of the cast product needs to be transferred by overlapping and pressing, the descending speed of the rod 5 of the elevating means 4 is set in the following three stages.
(1) a first speed at which the upper mold descends to a position immediately before the upper mold starts to contact the surface of the molten metal 9 poured into the recess 15 of the lower mold F2,
(2) a second speed for lowering the upper mold F1 from a position immediately before the upper mold starts to contact the surface of the molten metal 9 to a position where the pressure of the molten metal 9 in the mold reaches a preset pressure;
(3) The speed after the position where the preset pressure is reached is switched to a third speed at which the upper mold is lowered to the press completion position.
Here, the third speed is set slower than the second speed, and the second speed is set slower than the first speed.
The detection means 10 includes a reaction force value acting on the upper mold by the pressure of the molten metal 9 and a reaction force value (upper and lower molds) that the upper mold F1 receives from the lower mold F2 when the upper mold F1 is superimposed on the lower mold F2. ) Is detected.
In the third embodiment, the detection means 10 detects the reaction force value received by the upper mold F1 superimposed on the lower mold F2 from the molten metal 9 and the lower mold F2, and the reaction force value is calculated. Based on this detection signal, the operation of the elevating means 4 is controlled so as to stop the lowering of the upper mold F1 at the press completion position based on the detection signal. ing.

  The predetermined position of the upper mold F1 (the position at which the lowering speed of the upper mold is switched from the first speed to the second speed) is the first speed of the shape of the bulging portion 12 of the upper mold F1 and the lowering speed of the upper mold. It is determined depending on. For example, when the surface of the bulging portion 12 is flat and the first speed is high, the wind pressure due to the lowering of the upper mold F1 is increased, the surface of the molten metal 9 is disturbed, and the air flows when the upper and lower molds F1, F2 are overlapped. Therefore, it is necessary to set the position where the lower mold lowering speed is switched from the first speed to the second speed upward. That is, it is necessary to widen the distance between the position of the upper mold where the lowering speed of the upper mold is switched from the first speed to the second speed and the surface of the molten metal 9. On the other hand, when the first speed is slow, the molten metal 9 is solidified during the pressing process, and the upper mold F1 may not reach the press completion position. The distance between the position of the upper mold for switching from the speed to the second speed and the surface of the molten metal 9 must be reduced. Accordingly, the predetermined position (the position at which the lowering speed of the upper mold is switched from the first speed to the second speed) and the first speed, which is the first lowering speed of the upper mold, are determined in advance in the form of the cast product or the molten metal. It is desirable to set experimentally considering the pouring temperature and the material of the molten metal. In the present embodiment, the bulging portion 12 as a form of the cast product has a pyramid shape, and the molten metal pouring temperature is higher than the melting point temperature by 100 to 200 ° C., so the first speed is set. The maximum speed according to the specifications of the electric servo cylinder as the lifting means 4 is set to, for example, about 375 mm / s, and a predetermined position (position where the lowering speed of the upper mold is switched from the first speed to the second speed) is set to 1 to 2. It is set to 100 mm.

In order to stop the upper mold F1 at a position where the upper and lower molds F1 and F2 start to contact and do not cause the mold to be deformed, the predetermined pressing force P2 is determined by the area of the parting surface of the upper mold and the form of the upper and lower molds. It is desirable to set beforehand by experiment based on the press speed.
In the third embodiment, the experiment was performed by changing the temperature of the molten metal (the pouring temperature). According to the pressurizing curve when the pouring temperature is about 1406 ° C (shown experimentally, the horizontal axis is the lowering distance of the upper mold and the vertical axis is the molten metal's pressing force) For example, after the upper mold is lowered at the second speed, the applied pressure gradually increases from the position where the upper mold starts to contact the lower mold, and is applied in a substantially linear state from the position where the upper mold is lowered to a predetermined distance. The pressure begins to rise. In the applied pressure curve of this experiment, the difference in applied pressure from the position where the upper mold started to contact the lower mold to the position where the mold was not deformed was 0.010 MPa. The experimental condition was that the area of the parting surface of the upper mold was 88842 mm ² , and the second speed as the lowering speed of the lifting means 4 was 30 mm / s.

Next, an experiment was conducted in the case where the pouring temperature was about 1363 ° C. under the same experimental conditions. The pressure curve of this experiment is the same as the pressure curve described above, after the upper mold is lowered at the second speed and the upper mold starts to contact the lower mold, and then the pressure increases gradually. The pressing force starts to increase in a substantially straight line from the position where the mold has been lowered to a predetermined distance. In the applied pressure curve of this experiment, the difference in applied pressure from the position where the upper mold started to contact the lower mold to the position where the mold was not deformed was 0.011 MPa. Therefore, even if the pouring temperature changes, the applied pressure curve is almost the same, and the applied pressure until the upper mold starts to contact the lower mold is the same as when the bulging part of the upper mold enters the molten metal in the lower mold. Although there is a slight difference in the pressure applied to the position where the upper and lower molds start to contact, due to the viscosity of the molten metal, etc., there is a difference from the position where the upper mold starts to contact the lower mold to the position where mold deformation does not occur. The pressure draws a similar curve. (In other words, there is not much difference due to the pouring temperature.)
For this reason, in the present invention, the pressure curve shows the same characteristics even when the pouring temperature changes, and therefore, from the position where the upper mold starts to contact the lower mold to the position where the mold is not deformed. In this range, the lowering of the upper mold can be stopped at an appropriate position based on the distance by which the upper mold is lowered. In this case, position detectors such as the rotary encoder and linear scale can be used as means for detecting the position of the upper mold.

In the third embodiment, the pressurizing curve shows the same characteristics even when the pouring temperature changes, so the press completion position (upper mold stop position) is set according to the lower mold lowering distance. You can do that. That is, the lowering distance of the upper mold is set in a state where molten metal (molten metal) is poured into the lower mold. However, the lowering distance in the state with the molten metal is the lowering distance when the reaction force of the molten metal is applied to the upper mold. For this reason, there is a possibility that the actual descent distance is not accurately reflected. In addition, sand molds vary in mold dimensions, particularly mold height, with changes in molding pressure, sand properties, model shape, and the like.
Therefore, in order to set a more accurate descent distance, the pressure (pressing force) applied to the upper mold in the process of overlaying the upper mold on the lower mold is measured in a state where there is no molten metal in the lower mold, and a predetermined applied pressure is measured. A lowering distance of the upper mold is set as a press completion position where the lowering of the upper mold is stopped when pressure is applied.

  In the present embodiment, the press speed is switched at a set position before the pressure in the mold generated when the molten metal enters the upper mold having the raised portion becomes an excessive pressure, but in the present invention, However, the present invention is not limited to this, and for example, it can also be applied to upper and lower molds in which the shape of the cast product is complicated in addition to the raised portion, and pressure fluctuation during press tends to occur.

  In this case, the press speed to be applied in the case of a complicated mold shape is designed. A pressure rise interval during pressing is estimated from the shape data of the mold, and a pressing speed for suppressing the pressure fluctuation below a desired pressure constraint value is determined. The press speed is switched in multiple stages according to changes in the flow path of the molten metal below the molten metal surface. In order to speed up the pressing process, the maximum output speed of the lifting device is used until immediately before the upper mold contacts the molten metal. Thereafter, in order to satisfy the pressure constraint, the press speed is sequentially switched to the low speed side by multistage switching.

  Further, in the embodiments so far, a framed mold is used. However, in the present invention, the present invention is not limited to this. For example, a back metal mold or a sand mold from a cast frame after molding or after mold matching. It is possible to use a punched frame mold for extracting. In addition, when using a punched frame mold for extracting the sand mold from the casting frame after this mold matching, a stamping means for separating the cast frame and the sand mold is provided in the press device, so that the mold added to the tip of the rod of the lifting means is added. A pressing device having a configuration in which the pressure plate and the fixing means for supporting the upper mold are omitted, the upper mold and the lower mold after molding are supported as guide rods, and the lifting / lowering means is guided.

1 is a schematic configuration diagram of a casting press apparatus according to Embodiment 1 of the present invention. It is a figure which shows the structure of the system which controls the descent speed of an upper casting_mold | template. It is the schematic of a press process. It is a figure which shows the relationship between the reaction force which acts on the upper casting_mold | template obtained by CFD analysis, and the reaction force value measured with a load cell. It is a figure which shows the shape of a simple mold (thing for giving the mathematical model on analysis). It is a figure which shows the change of the fluid liquid level position in a simple mold (thing for giving the mathematical model on analysis). It is a figure which shows the fluctuation | variation of a pressure in case a press speed is 5 (mm / s). It is a figure which shows the fluctuation | variation of a pressure in case a press speed is 30 (mm / s). It is a flowchart of sequence speed control for upper mold lowering speed change. It is a figure which shows the result of the simulation analysis for evaluating the inhibitory effect of the molten metal pressure by switching the descent speed of an upper casting_mold | template. FIG. 2 is a control block diagram of a press apparatus. It is a figure which shows the shape of the simple casting_mold | template in Embodiment 2. FIG. 10 is a flowchart for controlling the lowering speed of the upper mold in the second embodiment. 12 is a flowchart for switching the lowering speed of the upper mold according to the third embodiment.

Claims (11)

A lower mold into which a predetermined amount of molten metal necessary for casting the cast product is injected, and a cavity for casting the cast product are defined by pressing the lower mold so as to overlap the lower mold. A casting method for casting a cast product using a mold composed of an upper mold,
A casting product casting method for controlling the press speed by estimating the pressure applied to the molten metal in the pressing process using the pressure estimation means of the molten metal in the mold based on the shape data of the upper and lower molds. 2. The casting product casting method according to claim 1, wherein the molten metal pressure estimating means estimates the molten metal pressure in the mold using the descending speed of the upper mold as a parameter. The casting method for a cast product according to claim 1, further comprising a step of switching a press speed when the pressure of the molten metal in the mold reaches a preset pressure. 3. The casting method for a cast product according to claim 1, wherein the upper mold has a raised portion of a molten metal at a predetermined portion. Detecting the position of the upper mold when the upper mold starts to contact the molten metal when the upper mold is superimposed on the lower mold and pressed;
4. The casting product according to claim 3, further comprising the step of stopping the lowering of the upper mold after detecting that the upper mold is further lowered and the position of the upper mold has reached a predetermined position. Casting method. Detecting the reaction force from the molten metal acting on the upper mold when the upper mold starts to contact the molten metal when the upper mold is superimposed on the lower mold and pressed;
And a step of stopping the lowering of the upper mold after detecting that the upper mold is further lowered and the reaction force from the molten metal acting on the upper mold reaches a predetermined value. The casting method of the cast product according to claim 3. A press apparatus used in a casting method for a cast product according to claim 1 or 2,
A movable frame;
Elevating means provided on the movable frame;
A guide rod for guiding the raising and lowering of the elevating means;
Detecting means for detecting the state of the upper mold;
Storing the pressure estimation means of the molten metal, and controlling the operations of the movable frame, the lifting means and the fixing means, and the control means for controlling the operation of the lifting means based on the detection data of the detection means. A casting press machine characterized by the above. 8. The casting press apparatus according to claim 7, wherein the upper mold has a raised portion of molten metal at a predetermined site. A lowering speed of the upper mold driven by the elevating means includes a first speed for lowering the upper mold to a position where the pressure of the molten metal in the mold reaches a preset pressure, and a melting in the mold. The metal pressure is set to a second speed for lowering the upper mold in a region below the position where the preset pressure is reached, and the second speed is set lower than the first speed. The casting pressing device according to claim 7 or 8. The detecting means detects the external force acting on the upper mold superimposed on the lower mold or the position of the upper mold, and the control means stores the external force data acting on the upper mold or the position data of the upper mold. The casting press apparatus according to claim 7 or 8, wherein A lowering speed of the upper mold driven by the elevating means includes a first speed for lowering the upper mold to a position where the upper mold starts to contact the liquid surface of the molten metal, and a molten metal in the mold applied to the upper mold. A second speed for further lowering the upper mold until the pressure reaches a preset pressure, and after the pressure of the molten metal in the mold applied to the upper mold reaches the preset pressure, the upper mold is moved to the completion position. 11. The casting according to claim 10, wherein the second speed is set lower than the first speed, and the third speed is set lower than the second speed. Press device.

Images