JP2899742B2 - Pressure casting equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure casting apparatus for pressurizing a molten metal with a pressure pin at a stage where the molten metal filled in a cavity solidifies, and more particularly, to a case where the pressure pin is advanced at a very low speed. The present invention relates to a pressure casting apparatus for detecting a solidification state of a molten metal from a repulsive force applied to the pressure casting apparatus and determining a timing for performing pressure.

[0002]

2. Description of the Related Art In a casting technique such as a die casting method,
In order to prevent the occurrence of defects such as shrinkage and cavities caused by the solidification shrinkage of the molten metal, pressure casting is performed to pressurize the molten metal at the stage of solidifying the molten metal filled in the cavity. In order to perform effective pressurization in such pressurized casting, it is extremely important to appropriately set the timing for operating the pressurizing means such as a pressurizing pin. Therefore, various methods for setting the timing of pressurization have been developed, and one example thereof is disclosed in Japanese Patent Application Laid-Open No. 4-182553. In the technique described in this publication, a pressure pin is first advanced at a very low speed by a hydraulic cylinder for driving the pressure pin after a lapse of a predetermined time from the completion of filling of the molten metal.
Then, when the repulsion force received by the pressure pin reaches a predetermined pressure, it is determined that the molten metal has reached a predetermined solidification state,
The pressure is applied by advancing the pressure pin at high speed. in this way,
The timing of pressurization is determined by detecting the repulsive force received by the pressurizing pin that advances at a slow speed through the hydraulic system.

[0003]

An example of the result of the pressure casting obtained by the above technique will be described with reference to FIG. FIG. 4A is a diagram showing a change over time of the movement amount of the pressure pin in the conventional pressure casting, and FIG. 4B is a diagram showing a change over time of the pressure applied to the pressure pin. FIG.
The vertical axes of (A) and (B) indicate the movement amount L of the pressure pin and the pressure P applied to the pressure pin, respectively, and the pressure pa is a pressure corresponding to the above-described predetermined solidification state. In the above-mentioned technique, control is performed in which a pressure pin is advanced at a very low speed to detect a solidification state of the molten metal after a lapse of a predetermined time from the filling of the molten metal. Here, as shown in FIG. 4 (A), there is a stagnation time T11 during which the pressure pin does not move after the control of the slow speed advance is performed and before the pressure pin actually starts to advance.
The stagnation time T11 is a delay caused by the presence of elasticity in the hydraulic circuit due to air or the like contained in the pressure oil.

Further, there is a time from when the pressure pin starts to move forward until it reaches a predetermined speed.
As shown in (B), the rise time T1 is between the time when the control is performed and the time when the pressure pin is set to the predetermined slow speed advance state.
It takes two. Time T from the time when the pressure pin starts
After 13, the pressure P applied to the pressure pin reaches the predetermined pressure pa, so that a high oil pressure is supplied to the hydraulic cylinder, the pressure pin advances at high speed, and the molten metal is pressurized for a time T14. As described above, in the above-described technique, the rise time T12 is required until the pressure pin is set to the predetermined slow-moving state and the coagulation state can be detected. Therefore, in the case of high-precision pressure casting, when the pressing start timing is early, the pressing start timing comes within the rise time T12, so that it is not possible to appropriately control the pressing start.
Further, since the rise time T12 is long, the cycle time is also long, and there is a problem that the efficiency of pressure casting is reduced. Such a problem is because, in order to advance the pressure pin at a very low speed, it is necessary to control the pressure oil supplied to the hydraulic cylinder to a very small amount, and it takes a long time until the elasticity existing in the hydraulic circuit is removed. It occurs in.

Accordingly, in the inventions according to claims 1 and 2 of the present application, the rise time is shortened by quickly removing the elasticity in the hydraulic circuit before the pressurizing pin is advanced at a very low speed, thereby reducing the rise time. It is an object of the present invention to provide a pressure casting apparatus which increases the efficiency of pressure casting and enables high-precision pressure timing control. Another object of the present invention is to provide a pressure casting apparatus that can secure a sufficient pressure stroke while performing high-precision pressure timing control.

[0006]

In order to solve the above-mentioned problems, according to the first aspect of the present invention, in order to pressurize the molten metal at the stage of solidification of the molten metal filled in the cavity, the molten metal is applied to the cavity. A pressurizing pin provided in front thereof, and a hydraulic drive means for driving the pressurized pin by supplying pressure oil to advance the pressurized pin in the direction of the cavity; In a pressure casting apparatus that detects the solidification state of the filled molten metal from the repulsive force received by the pressure pin and determines the timing of performing pressure, before the pressure pin is advanced at a very low speed, A pressure casting apparatus characterized by having a pressure oil supply means for temporarily supplying a large amount of pressure oil to the hydraulic drive means has been created.

Here, "facing the cavity" means that the tip of the pressure pin projects or faces into the cavity. The "hydraulic driving means" includes driving means using hydraulic pressure, such as a hydraulic cylinder and a hydraulic motor. Further, as a method of measuring the repulsive force received by the pressure pin, various methods including, for example, attaching a pressure sensor to a part of the hydraulic system are included. Further, “a large amount of pressure oil” means that it is larger than the pressure oil supplied to the hydraulic drive means when the pressurizing pin is advanced at a very low speed, and indicates a relatively large amount. . Further, "temporarily" means a short time as compared with the time when the pressure pin advances at a very low speed. The method of filling the cavity with the molten metal in pressure casting includes gravity casting,
Various casting methods such as reduced pressure casting, differential pressure casting, and die casting are included.

According to a second aspect of the present invention, in the pressure casting apparatus according to the first aspect, there is provided a moving amount measuring means for measuring a moving amount of the pressing pin, and the moving amount measuring means is provided. A pressure casting apparatus characterized in that the pressure oil supply means is switched from a state in which a large amount of pressure oil is supplied to a state in which a small amount of pressure oil is supplied when a movement amount measured by the pressure reaches a predetermined amount. did. Here, the "moving amount measuring means" includes all means capable of measuring the moving amount of the pressing pin, that is, the change of the tip position of the pressing pin.
For example, a hydraulic cylinder for pressurizing with a differential transformer or a potentiometer, a linear encoder, an optical encoder, and a unit for irradiating a laser beam to a part of the pressurizing pin to measure a moving amount are included. .

[0009]

In the pressure casting apparatus according to the first aspect of the present invention, a pressure pin for pressing the molten metal at the stage of solidification of the molten metal filled in the cavity is provided facing the cavity. The pressure pin is driven by the supply of pressure oil to the hydraulic drive means, and advances toward the cavity to pressurize the molten metal. The timing of this pressurization is determined by advancing the pressurizing pin at a very low speed by the hydraulic drive means and detecting the solidification state of the filled molten metal from the repulsive force received by the pressurizing pin. In such a pressure casting apparatus, a large amount of pressure oil is temporarily supplied to the hydraulic drive means by the pressure oil supply means before the pressure pin is advanced at a slow speed in order to detect the solidification state. As a result, the elasticity factor present in the hydraulic circuit due to air in the pressure oil or the like is quickly removed, and then the pressure oil supply unit is switched to a state in which a small amount of pressure oil is supplied, thereby detecting the solidification state. Is performed. Therefore, the rise time until the coagulation state can be detected is shortened, and accurate detection and determination can be performed even at an early pressurization timing. Also, the cycle time of casting is reduced. In this way, the casting efficiency is improved, and a pressure casting apparatus capable of performing high-precision pressure timing control is provided.

Further, the pressure casting apparatus according to the present invention has a movement amount measuring means for measuring the movement amount of the pressure pin, and the movement amount measured by the movement amount measuring means is equal to a predetermined amount. When the pressure oil reaches, the pressure oil supply means is switched from a state of supplying a large amount of pressure oil to a state of supplying a small amount of pressure oil. Thus, the amount of movement of the pressure pin for removing elasticity in the hydraulic circuit is always limited to a predetermined amount, and no extra stroke is consumed. Therefore, it is possible to shorten the rise time and increase the accuracy of the determination of the pressurization timing while maximizing the stroke actually used for pressurization among the entire strokes of the pressurizing pin. In this way, a pressure casting apparatus that enables high-precision pressure timing control and ensures a sufficient pressure stroke is provided.

[0011]

Next, an embodiment of the present invention will be described with reference to FIGS. First, the overall configuration of the pressure casting apparatus of the present embodiment will be described with reference to FIG.
As shown in FIG. 1, the pressure casting apparatus 2 of the present embodiment has a pressure pin 10, and the tip of the pressure pin 10 faces a cavity (not shown). The rear end of the pressure pin 10 is fixed to the hydraulic piston 8 of the pressure hydraulic cylinder 4.
The hydraulic system moves forward and backward integrally with the hydraulic piston 8 by the operation of the hydraulic system. The hydraulic system of the pressure casting device 2 includes a hydraulic pressure source 20, an electromagnetic direction switching valve 30, an electromagnetic on-off valve 40, a flow control valve 50, and a hydraulic pipe connecting these components. The flow direction of the pressure oil of the hydraulic pressure source 20 is switched from the hydraulic pipe 22A to the hydraulic pipe 22B or 24 by the electromagnetic direction switching valve 30. The pressure oil of the hydraulic pipe 22B is changed to the electromagnetic switching valve 40.
Alternatively, the hydraulic pipe 22C, the flow control valve 50, the hydraulic pipe 22
It is guided to the rear chamber 6A of the pressurizing hydraulic cylinder 4 via E.

A hydraulic pipe 22C branches off from the hydraulic pipe 22B. The hydraulic pipe 22B is connected to an electromagnetic on-off valve 40, and the hydraulic pipe 22C is connected to a flow control valve 50, respectively. Further, the flow control valve 50 has a check valve 52 arranged in parallel via a bypass pipe 22D. These hydraulic piping 2
2C and 22D join a hydraulic pipe 22E connecting the electromagnetic on-off valve 40 and the rear chamber 6A of the hydraulic cylinder 4. on the other hand,
A hydraulic pipe 24 is connected to the front chamber 6B of the hydraulic cylinder 4 for pressurization.
, A hydraulic path returning to the oil tank 28 is formed. The electromagnetic directional control valve 30 and the electromagnetic on-off valve 40 are operated by control signals sent from the control computer 60 through control signal lines 64 and 66, respectively.

The directional control valve 30 has three switching positions 34.
A, 34B, and 34C. When the electromagnetic solenoid 32 is not operated, the valve body (not shown) is moved to the left end by the urging force of the spring 36 and is switched to the switching position 34C.
That is, the hydraulic pipes 22A and 24 and the hydraulic pipes 22B and 26
Are communicated, and hydraulic pressure is supplied to the front chamber 6B of the pressurizing hydraulic cylinder 4 via the hydraulic pipes 22A and 24. As a result, the hydraulic piston 8 retreats, and the oil in the rear chamber 6A is discharged from the pipes 22E and 22D, the check valve 52, and the hydraulic pipes 22C and 2C.
The oil is returned to the oil tank 28 via 2B and 26. When the control computer 60 controls the electromagnetic solenoid 32 to a state of a low excitation force, the valve body moves against the urging force of the spring 36, and switches to the central switching position 34B.
State. That is, each of the hydraulic pipes 22A, 22B,
Since the pressurizing hydraulic cylinder 4 is shut off from the hydraulic pressure generation source 20 in the closed state, the hydraulic piston 8 stops. When the electromagnetic solenoid 32 is further controlled to a high exciting force, the electromagnetic direction switching valve 30 is switched to the switching position 34A, and from the hydraulic pipes 22A and 22B via the electromagnetic on-off valve 40 or the flow regulating valve 50, Pressure oil is supplied to the rear chamber 6A. As a result, the hydraulic piston 8 moves forward, and the oil in the front chamber 6B is released from the hydraulic pipes 24 and 26.
Is returned to the oil tank 28.

On the other hand, the solenoid on-off valve 40 has two switching positions 4
4A and 44B, and when the electromagnetic solenoid 42 is not operated, it is switched to the closed state switching 44B by the urging force of the spring 46 (the state shown in FIG. 1). In this state, the electromagnetic directional control valve 30 is switched to the switching position 34A.
, The pressure oil is supplied to the rear chamber 6A of the pressurizing hydraulic cylinder 4 via the flow control valve 50. Flow control valve 5
The flow rate of 0 is previously adjusted to a very small amount, whereby the pressurizing pin 10 advances at a very low speed together with the hydraulic piston 8. When the electromagnetic solenoid 42 is excited by a control signal from the control computer 60, the valve body (not shown) moves against the urging force of the spring 46 and switches to the open switching position 44A, and the hydraulic piping 22B , 22E. Thereby, a large amount of pressure oil from the hydraulic pipe 22B is supplied to the rear chamber 6A of the pressurizing hydraulic cylinder 4,
The pressurizing pin 10 advances at high speed together with the hydraulic piston 8. Thus, by opening and closing the electromagnetic on-off valve 40,
The advance speed of the pressure pin 10 is controlled.

Further, a pressure sensor 5 is connected to the hydraulic pipe 22E.
The pressure sensor 54 measures the magnitude of the hydraulic pressure applied to the rear chamber 6A of the pressurizing hydraulic cylinder 4, that is, the pressure received by the pressurizing pin 10.
Data measured by the pressure sensor 54 is input to the control computer 60 via a measurement signal line 68. Further, a differential transformer 12 is provided in the pressurizing hydraulic cylinder 4, and the differential transformer 12 measures a moving amount of the hydraulic piston 8, that is, a stroke amount of the pressurizing pin 10.
The measurement signal is transmitted to the control computer 6 through the signal line 14.
Input to 0. The control computer 60 has a memory 62 in which a set pressure Pa and a set stroke La are stored. The set pressure Pa is a pressure corresponding to a repulsive force received by the pressing pin when the solidification state of the molten metal becomes a state suitable for starting pressurization. The control computer 60 compares the data of the set pressure Pa with the pressure measured by the pressure sensor 22 input via the signal line 68, and determines whether the set pressure Pa has been reached.

On the other hand, the set stroke La is used as a criterion for judging that elasticity such as air in the pressure oil is crushed by the supply of a large amount of pressure oil and the elasticity in the hydraulic circuit is removed. Is set. Therefore, it is desirable that the set stroke La be as short as possible. In this embodiment, La is set to 0.2 mm. Whether the pressure pin 10 has moved by the set stroke La or not is determined by comparing the data of the set stroke La in the memory 62 and the measured movement amount of the differential transformer 12 inputted through the signal line 14 with the control computer 60. Is performed by comparison.

The pressure casting apparatus 2 having the above structure
2 will be described with reference to FIG. 1 and according to the flowchart of FIG. FIG. 2 is a flowchart showing a procedure of pressure casting in the pressure casting apparatus 2 of the present embodiment. At the start of the pressure casting, the hydraulic piston 8 of the pressurizing hydraulic cylinder 4 is at the retracted position. Also, the electromagnetic direction switching valve 30 has the hydraulic pressure pipes in the valve chamber 34B fully closed, and the electromagnetic on-off valve 40 is also closed (the state shown in FIG. 1). When the control is started in step S10, the injection plunger of the pressure casting device 2 advances, and the molten metal is filled into the cavity through the gate, runner, and gate of the casting mold. (Step S12). After the set time t has elapsed from the completion of the filling of the molten metal, the electromagnetic direction switching valve 30 is in the switching position 34A and the electromagnetic on-off valve 40 is in the switching position 44A. That is, both the solenoid valves 30 and 40 are opened (step S14), whereby a large amount of pressure oil is supplied from the hydraulic pipe 22B to the rear chamber 6A of the pressurizing hydraulic cylinder 4 through the solenoid on-off valve 40. By supplying such a large amount of pressure oil, an elastic factor such as air in the pressure oil is crushed, and the elasticity in the hydraulic circuit is promptly removed.

As described above, the set stroke La is used as a reference as a measure of the completion of the elastic removal. Therefore, it is determined whether or not the amount of movement of the pressure pin 10 has reached the set stroke La (step S16), and the determination is repeated until the result becomes YES. Then, the detection operation of the solidification state of the molten metal is started at the time of moving by the set stroke La (step S18). That is,
With the electromagnetic directional control valve 30 opened, the electromagnetic on-off valve 40 is closed, the pressure oil is supplied to the rear chamber 6A of the pressurizing hydraulic cylinder 4 via only the flow control valve 50, and the pressurizing pin 10 moves forward at a very low speed. Switch to state. Subsequently, it is determined whether the pressure received by the pressure pin 10 (that is, the value measured by the pressure sensor 54) has reached the set pressure Pa (Step S20). The pressurizing pin 10 continues to advance at a very low speed until this determination becomes YES, and when the set pressure Pa is reached, pressurization of the molten metal is started (step S22). That is, a control signal for opening the electromagnetic on-off valve 40 is output, and a high pressure is again applied to the rear chamber 6A of the pressurizing hydraulic cylinder 4, so that the pressurizing pin 10
Moves forward at a high speed to pressurize the molten metal.

After a certain period of time has elapsed since the start of pressurization, the electromagnetic direction switching valve 30 switches to the switching position 34B, and the pressurizing pin 10 stops (step S24). Subsequently, the pressure is switched to the switching position 34C, the pressurizing pin 10 moves back together with the hydraulic piston 8 and returns to the original position, and the pressurization ends (step S26). After the molten metal is sufficiently cooled and solidified, the casting mold is opened, the casting in the cavity is taken out, and one casting step is completed. In this way, in the pressure casting apparatus 2 of the present embodiment, the elasticity in the hydraulic circuit is quickly removed by temporarily supplying a large amount of pressure oil before the pressure pin 10 is advanced slowly. This reduces the rise time. As a result, even when high-precision pressure casting is performed and the pressing start timing is early, appropriate pressing start control can be performed, and high-precision pressing timing control can be performed. Further, the cycle time of pressure casting is shortened, and the efficiency of casting is improved.

The results obtained by such pressure casting will be described with reference to FIGS. FIG.
FIG. 3A is a diagram showing a change over time of a moving amount of a pressure pin in the pressure casting apparatus of the present embodiment, and FIG. 3B is a diagram showing a change over time of a pressure applied to the pressure pin. FIG. 3 (A)
The vertical axis indicates the movement amount L of the pressure pin, and the vertical axis in FIG. 3B indicates the pressure P applied to the pressure pin. In this embodiment as well, there is a stagnation time T1 as shown in FIG. 3 (A). However, a large amount of pressure oil is temporarily supplied before the pressing pin 10 is advanced at a low speed, and the elasticity in the hydraulic circuit is reduced. Is quickly removed, so that it is significantly shorter than the stagnation time T11 in FIG. Therefore, as shown in FIG. 3 (B), the rise time T2 until the pressure pin is set to the predetermined very low speed advance state is also extremely short (3.5 seconds in the conventional example, but in this embodiment, it is 3.5 seconds). In this case, the time was shortened to 0.8 seconds), so that the coagulation state can be detected early.

The present embodiment mainly corresponds to the second aspect of the present invention. However, a waiting time (t) between the time when the cavity is filled with the molten metal and the time when a large amount of pressure oil is supplied is supplied.
Is not an essential requirement of the invention of claim 2.
In the present embodiment, the hydraulic cylinder 4 and the hydraulic piston 8 are used as the hydraulic drive means for the pressure pin 10, but other hydraulic drive means such as a hydraulic motor may be used. Further, the differential transformer 12 is attached to the pressurizing hydraulic cylinder 4 as a means for measuring the moving amount of the pressurizing pin 10, but other moving amount measuring means such as a potentiometer, a linear encoder, and a laser measuring device may be used. it can. Further, as a method of measuring the pressure received by the pressure pin 10, the pressure sensor 54 is attached to the hydraulic pipe 22E. However, other pressure measuring means may be used, or the pressure measuring means may be directly attached to the pressurizing hydraulic cylinder 4. A method may be used. Furthermore, as the electromagnetic direction switching valve 30 for switching the flow direction of the pressure oil, an electromagnetic solenoid 32 is attached to one of the valves, but an electromagnetic solenoid attached to both of the valves may be used. The composition, shape, size, material, number,
The connection relation and the like are not limited to the present embodiment.

[0022]

According to the first aspect of the present invention, a pressure casting apparatus for temporarily supplying a large amount of pressure oil and quickly removing the elasticity in the hydraulic circuit before the pressure pin is advanced at a low speed is created. In addition, the rise time of coagulation state detection is shortened,
The casting efficiency is improved, and highly accurate pressurization timing control becomes possible. As a result, a suitable pressure can be applied to the molten metal, and a practical pressure casting apparatus capable of stably and efficiently obtaining a high-quality casting without shrinkage or cavities. Further, as a ripple effect of the present invention, since the start time of the coagulation state detection is accurate, it is possible to set the detection start time closer to the expected pressurization start time. Therefore, it is possible to shorten the slow forward stroke for detection,
There is an advantage that a longer pressurizing stroke can be taken.

According to the second aspect of the present invention, a pressure casting apparatus for switching to a state in which a small amount of pressure oil is supplied when the moving amount of the pressure pin reaches a predetermined amount is created. The amount of movement of the pressure pin for removing the elasticity is always limited to a predetermined amount, and no extra stroke is consumed. As a result, an extremely practical pressure casting apparatus can be obtained, which can perform high-precision pressure control and can secure a sufficient pressure stroke.

[Brief description of the drawings]

FIG. 1 is a view showing an entire configuration of an embodiment of a pressure casting apparatus according to the present invention.

FIG. 2 is a flowchart showing a procedure of pressure casting in an embodiment of the pressure casting apparatus.

FIG. 3 is a diagram showing a change over time in the amount of movement of a pressure pin and the pressure applied to the pressure pin in one embodiment of a pressure casting apparatus.

FIG. 4 is a diagram showing a change over time of a movement amount of a pressure pin and a pressure applied to the pressure pin in a conventional pressure casting apparatus.

[Explanation of symbols]

 2 Pressure Casting Device 4,8 Hydraulic Driving Means 10 Pressure Pin 12 Movement Measuring Means 20,22,30,40,50 Pressure Oil Supplying Means

Continued on the front page (72) Inventor Mitsuru Karaki 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Co., Ltd. (72) Inventor Mitsuru Inui 1-9-6 Rokujo Minami, Gifu City, Gifu Prefecture Gifu Seiki Co., Ltd. 1st Division (72) Inventor Kento Nimura 1-9-6 Rojo Minami, Gifu City, Gifu Prefecture 1st Division of Gifu Seiki Industry Co., Ltd. (72) Inventor Akira Saito 1-9-, Rojo Minami, Gifu City, Gifu Prefecture 6 Gifu Seiki Kogyo Co., Ltd. 1st Business Unit (72) Inventor Juichi Nakamura 45-kai, Hachiji-cho, Okazaki-shi, Aichi Pref. 182053 (JP, A) JP-A-5-253658 (JP, A) JP-A-5-146860 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B22D 17/22 B22D 17 / 32

Claims (2)

(57) [Claims] 1. A pressure pin provided to face the cavity to pressurize the molten metal in a stage where the molten metal filled in the cavity solidifies, and the pressure oil is supplied to drive the pressure pin. Hydraulic drive means for advancing in the direction of the cavity and detecting the solidification state of the filled molten metal from the repulsive force received by the pressure pin by moving the pressure pin at a very low speed by the hydraulic drive means. In the pressure casting apparatus for determining the timing of performing the pressurization, it is preferable that a pressure oil supply unit that temporarily supplies a large amount of pressure oil to the hydraulic drive unit before the pressurizing pin is advanced at a low speed. Characteristic pressure casting equipment. 2. The pressure casting apparatus according to claim 1, further comprising a movement amount measuring means for measuring a movement amount of the pressure pin, wherein the movement amount measured by the movement amount measuring means is a predetermined amount. Wherein the pressure oil supply means is switched from a state in which a large amount of pressure oil is supplied to a state in which a small amount of pressure oil is supplied.