JP2007069235A - Gravity casting machine, and method of gravity casting to be used for the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gravity casting machine which can freely set a dropping speed without relying upon the gravity, the dropping speed having a most remarkable effect on the relationship between the filling rate and the speed of molten metal. <P>SOLUTION: A hydraulic servo mechanism 16 is arranged between a speed control valve 14 and a hydraulic cylinder 17. The hydraulic servo mechanism 16 is used for damping and controlling a vibration, and is added at the back of the speed control valve 14. When the gravity casting is carried out, the casting machine is tilted from 0° to 90° by the extending motion of the hydraulic cylinder 17 while extending and contracting it within the range of a response frequency. In this case, the frictional resistance greatly decreases by the minute vibration due to the extension and contraction of the hydraulic cylinder 17, and the molten metal drops while being accelerated by the effect of inertia. When the molten metal flows into the cavity of a metallic die 1, gas is necessarily generated. However, the air and gas existing in the cavity of the metallic die 1 are forcedly discharged by incorporating the hydraulic servo mechanism 16 as an exciting means of the hydraulic cylinder 17. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a gravity casting machine and a gravity casting method used therefor, and in particular, among casting methods that are a method of pouring molten metal into a mold to obtain a required casting shape, a casting is made using a casting machine having a tilt function. It relates to gravity casting.

  In recent years, the technical development of high-speed and high-pressure casting centering on die casting has been remarkable, but the casting machine with a tilt mechanism, so-called gravity casting method, is not controlled from the outside, such as high-speed and high-pressure, but literally it is left to gravity. The recognition of a casting method is common (see, for example, Patent Document 1). There has been no major technological advancement in this casting process for more than a quarter century.

  It is said that this casting method has advantages such as small die investment and suitable for small to medium volume production compared to die casting, but in terms of casting quality, casting work (pouring molten metal) is gravity. Since it is only left to fall, it is greatly influenced by the manufacturing know-how of molds, and the investment merit as before is fading, such as not much different from die-casting molds depending on the size.

Japanese Utility Model Publication No. 63-127661

  In the conventional gravity casting method described above, as shown in FIG. 2, the pouring cup 3 is filled with molten metal, and the hydraulic cylinder 4 is raised through the runner 2 to raise the internal cavity of the mold 1 (hereinafter referred to as a cavity). ) Is generally used.

In general, in most cases, filling is completed in the vicinity of an inclination angle of 45 degrees, and the falling speed v of the molten metal depends on the flow rate coefficient (C) with the inclination angle as a variable.
ν = C√2gh
The speed at the time of falling is determined by the height of the gate cup. Usually, for convenience, the drop speed at the height of the gate cup when the inclination angle is 45 degrees is estimated.

  As the name suggests, gravity casting is based on gravity drop, and the drop rate when molten metal fills the cavity is an important factor in casting quality (particularly the metal filling rate and speed). In order to arbitrarily set the speed at the time of falling, which is an effective means of improving these defects, such as nests that are internal defects in castings, poor hot water, etc. Effective measures cannot be taken as a function of

  Accordingly, an object of the present invention is to solve the above-mentioned problems, and a gravity casting machine that can arbitrarily set a falling speed that is most prominent in the relationship between the metal filling rate and the speed without depending on gravity, and to it. It is to provide a gravity casting method to be used.

The gravity casting machine according to the present invention is a gravity casting machine that injects molten metal into the mold by tilting the mold by raising a hydraulic cylinder,
A mechanism for accelerating the molten metal poured into the mold when the mold is tilted by the hydraulic cylinder is provided.

  The gravity casting method according to the present invention is a gravity casting method in which a molten metal is poured into the mold by tilting the mold by raising the hydraulic cylinder, and the mold is tilted when the mold is tilted by the hydraulic cylinder. The molten metal that is poured into is accelerated.

  That is, the gravity casting machine of the present invention is a gravity casting method for producing a casting by using a casting machine having an inclination function among casting methods that are a method of pouring molten metal into a mold and obtaining a required casting shape. In this case, the runway through which molten metal is poured into the mold is tilted, and at the same time, vibration is applied to the mold and the runway to greatly reduce the coefficient of friction and accelerate the fall speed due to gravity with the effect of inertia. The speed of reaching the inside of the mold can be arbitrarily set.

  More specifically, the gravity casting machine of the present invention adds a hydraulic servo for applying vibration to a hydraulic cylinder for inclining a runner into which molten metal is poured, thereby simultaneously inclining the mold and the machine while inclining the machine. The runner vibrates and drops the molten metal while accelerating it.

  As a result, in the gravity casting machine of the present invention, the hydraulic servo used for the damping effect and damping control is incorporated into the hydraulic system of the tilt casting machine as an oscillating function, so that the molten metal is filled in the mold while tilting. By constantly applying vibration, the frictional resistance is greatly reduced, and with the effect of inertia, the falling speed that is most prominent in the relationship between metal filling rate and speed is arbitrarily set without relying on gravity. It becomes possible.

  Further, in the gravity casting machine of the present invention, the molten metal is filled in the cavity, so that air and generated gas can be forcibly discharged by vibration from the escape route originally designed for the mold. Therefore, in the gravity casting machine of the present invention, in a gravity casting method using a general inclined casting machine, a hydraulic servo is used as an oscillating function based on a completely opposite concept to a normal one, thereby reducing the investment and reducing the cost. As a result, the casting quality can be improved.

  The present invention is configured and operated as described below, so that it is possible to arbitrarily set the falling speed that is most prominent in the relationship between the metal filling rate and the speed without depending on gravity. can get.

  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a hydraulic cylinder according to an embodiment of the present invention. In FIG. 1, a hydraulic cylinder according to an embodiment of the present invention acts on a motor 11, an oil tank 12, a pump 13, a speed control valve 14, a direction control valve 15, a hydraulic servo 16, and a load 18. The hydraulic cylinder 17 is configured to be configured. The gravity casting machine according to one embodiment of the present invention has the same configuration as the conventional gravity casting machine shown in FIG. 2, and the hydraulic cylinder 17 according to this embodiment is replaced with the hydraulic cylinder 4 of the gravity casting machine shown in FIG. Used for.

  In this embodiment, a hydraulic servo 16 is disposed between the speed control valve 14 and the hydraulic cylinder 17. There is also a directional control valve 15 between the speed control valve 14 and the hydraulic cylinder 17, but what is important is that a hydraulic servo 16 is arranged between the speed control valve 14 and the hydraulic cylinder 17, If there is a device that also serves as a control, only one type is required.

  The original purpose of the hydraulic servo 16 is to be used for damping effect and vibration control, but it is added after the speed control valve 14 to always vibrate the machine by switching operation at the time of gravity casting. In this range, the machine is tilted from 0 to 90 degrees by the operation of the hydraulic cylinder 17 extending while expanding and contracting.

  As described above, the falling speed of the molten metal due to the inclination of the machine can be expressed by using the flow coefficient (C) with the inclination angle as a variable. In this case, the flow velocity coefficient (C) is a coefficient of friction generated between the molten metal and the runner 2 when the molten metal is considered as a viscous fluid. Therefore, the frictional resistance is greatly reduced by the slight vibration caused by the expansion and contraction of the hydraulic cylinder 17, and the molten metal falls while accelerating due to the effect of inertia, so that it is possible to arbitrarily generate a speed independent of gravity.

  The cavity of the mold 1 is naturally filled with air, and when molten metal (750 to 800 ° C. in the case of aluminum) flows into the cavity, gas is inevitably generated. Various evacuation routes for air and gas have been devised in the mold 1 itself, but sometimes the generated gas becomes an obstacle, and it is inevitable that casting defects such as a casting nest and a poor hot water runoff are generated. In the casting method in which the hydraulic servo 16 according to the present embodiment is incorporated as a vibration function of the hydraulic cylinder 17, the effect of forcibly discharging air and gas in the cavity of the mold 1 can be exhibited.

  In the present embodiment, as described above, this is a very inexpensive method in which a hydraulic servo 16 that is normally used for a damping effect or damping control is incorporated as a vibration mechanism into a general hydraulic system.

  A gravity casting method according to one embodiment of the present invention will be described with reference to FIGS. In the gravity casting according to this embodiment, the mold (casting machine) 1 is inclined (0 → 90 degrees) by extending the hydraulic cylinder 4 while being finely expanded and contracted by the hydraulic servo 16.

  When the hydraulic cylinder 4 is contracted, the molten metal flowing through the runner 2 floats for a moment, and when the hydraulic cylinder 4 is next extended, the molten metal is accelerated downward by inertia. This operation is repeated within the range of the response frequency by repeating tens to hundreds of tens of cycles per second, thereby greatly reducing the frictional resistance generated between the molten metal and the runner 2 and gravity casting. However, it is possible to produce an operation having a great feature as a casting method in which the falling speed can be controlled by inertia.

  As described above, in this embodiment, the hydraulic servo 16 that is normally used for the damping effect and damping control is incorporated in the hydraulic system of the tilt casting machine as the vibration function of the hydraulic cylinder 17, so that the mold 1 is mounted in the hydraulic system. While filling the mold 1 with the molten metal while inclining, the friction resistance is greatly reduced by constantly applying vibration, and the relationship between the metal filling rate and the speed is most remarkable with the effect of inertia. A certain fall speed can be arbitrarily set without depending on gravity.

  Further, in the present embodiment, the molten metal is filled in the cavity of the mold 1, so that air or generated gas can be forcibly discharged by vibration from the escape path originally designed for the mold 1.

It is a block diagram which shows the structure of the hydraulic cylinder by one Example of this invention. It is a figure which shows the structure of the conventional gravity casting machine.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Mold 2 Runway 3 Spout cup 4 Hydraulic cylinder 5 Hydraulic unit 11 Motor 12 Oil tank 13 Pump 14 Speed control valve 15 Directional control valve 16 Hydraulic servo 17 Hydraulic cylinder 18 Load

Claims (8)

A gravity casting machine for inclining a mold by raising a hydraulic cylinder and pouring molten metal into the mold;
A gravity casting machine having a mechanism for accelerating molten metal poured into the mold when the mold is tilted by the hydraulic cylinder.   2. The gravity casting machine according to claim 1, wherein the mechanism for accelerating the molten metal is a hydraulic servo mechanism that vibrates by applying an expansion / contraction operation to a hydraulic cylinder for inclining the mold.   3. The gravity casting machine according to claim 2, wherein the hydraulic servo mechanism tilts the mold within a range of 0 to 90 degrees with the hydraulic cylinder while applying an expansion / contraction operation to the hydraulic cylinder. 4.   4. The gravity casting according to claim 2, wherein the hydraulic servo mechanism is disposed between a speed control valve that controls an inclination speed of the mold by the hydraulic cylinder and the hydraulic cylinder. 5. Machine.   A gravity casting method in which a mold is tilted by raising a hydraulic cylinder and molten metal is poured into the mold, and the molten metal that is poured into the mold is accelerated when the mold is tilted by the hydraulic cylinder. Gravity casting method characterized by that.   6. The gravity casting method according to claim 5, wherein the molten metal is accelerated by a hydraulic servo mechanism that vibrates by applying an expansion / contraction operation to a hydraulic cylinder for inclining the mold.   The gravity casting method according to claim 6, wherein the mold is tilted within a range of 0 to 90 degrees by the hydraulic cylinder while applying an expansion and contraction operation to the hydraulic cylinder by the hydraulic servo mechanism.   8. The gravity casting method according to claim 6, wherein the hydraulic servo mechanism is disposed between a speed control valve for controlling an inclination speed of the mold by the hydraulic cylinder and the hydraulic cylinder. 9. .

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