JP7409148B2 - Vacuum equipment and vacuum suction method - Google Patents

Description

The present invention relates to a vacuum device and a vacuum suction method used for vacuum suction in a die-casting machine or an injection molding machine.

Conventionally, there is a vacuum die casting machine that uses vacuum suction from a vacuum device to prevent gas (air) from getting caught up in the product when molten metal is pressurized into the mold cavity (for example, disclosed in Patent Document 1). .
FIG. 5 is an explanatory diagram of a conventional vacuum device. In the vacuum device 1, a vacuum suction valve 11, a filter 3, and a vacuum tank 12 are installed in order from the mold 2 side on a pipe 16 that connects an exhaust passage of the mold 2 and a vacuum pump 14. First, the vacuum suction valve 11 is closed, and the vacuum tank 12 is brought to the highest degree of vacuum using the vacuum pump 14. When pressurizing the molten metal into the cavity in the injection process, the vacuum suction valve 11 is opened and the molten metal is press-fitted at high pressure simultaneously with vacuum suction.

However, the gas sucked from the mold 2 during vacuum suction is diffused within the vacuum tank 12, and the vacuum pump 14 exhausts the gas inside the vacuum tank 12 to the atmosphere using only its original exhausting capacity. It is desirable that the vacuum tank 12 be maintained at the maximum degree of vacuum before starting the vacuum suction operation. Therefore, it is necessary to make the vacuum tank 12 reach the maximum degree of vacuum in a short time, but conventionally, this has been achieved by increasing the capacity and specifications of the pump. For this reason, the cost of the entire device increases, and a reduction in cost has been desired.

Japanese Patent Application Publication No. 2006-75850

In view of the above-mentioned problems of the conventional technology, the problem to be solved by the present invention is to be able to bring the vacuum tank to the maximum degree of vacuum in a short period of time, and contribute to cost reduction by shortening the cycle time and downsizing the vacuum pump. An object of the present invention is to provide a vacuum device and a vacuum suction method that can perform the following steps.

As a first means for solving the above problems, the present invention provides a vacuum pump that has a vacuum tank and sucks and discharges gas in a cavity;
comprising piping connecting the exhaust passage of the cavity and the vacuum pump,
The piping includes a straight pipe for rectifying the gas sucked into the exhaust passage side, and a hopper for collecting the rectified gas toward the vacuum pump side. It is an object of the present invention to provide a vacuum device characterized in that the sucked gas is first discharged before the gas flows into the vacuum tank and is diffused .
According to the first means, since the sucked gas is discharged first, the degree of vacuum in the vacuum tank is less deteriorated than when all the gas is sucked and diffused in the vacuum tank. The highest degree of vacuum can be reached in a short time.

As a second means for solving the above problem, the present invention provides a vacuum device characterized in that, in the first means, the straight pipe of the piping and the hopper are provided inside the vacuum tank. It is about providing.
According to the second means, in addition to the effects of the first means, the entire device can be made smaller.

As a third means for solving the above problems, the present invention provides a buffer tank between the hopper and the vacuum pump, and a gas pressure in the buffer tank that is controlled by the vacuum pump. It is an object of the present invention to provide a vacuum device characterized in that it is provided with a buffer check valve that closes when the exhaust capacity is exceeded.
According to the third means, when the gas pressure in the buffer tank exceeds the evacuation capacity of the vacuum pump during vacuum suction, suction gas is prevented from flowing into the vacuum tank and the degree of vacuum is prevented from decreasing, Vacuum suction cycle time can be shortened.

As a fourth means for solving the above problems, the present invention provides a vacuum suction method in which gas in a cavity is sucked and discharged using a vacuum pump equipped with a vacuum tank to reduce the pressure in the cavity to a vacuum state.
In a pipe that connects the exhaust passage of the cavity and the vacuum pump and includes a straight pipe for rectifying the gas sucked into the exhaust passage side and a hopper for collecting the rectified gas on the vacuum pump side , To provide a vacuum suction method characterized in that when the gas is sucked in a vacuum state, the sucked gas is first discharged before the gas flows into the vacuum tank and diffuses .
According to the fourth means, since the sucked gas is discharged first, the degree of vacuum in the vacuum tank is less deteriorated than when all the gas is sucked and diffused in the vacuum tank. The highest degree of vacuum can be reached in a short time.

As a fifth means for solving the above problem, the present invention provides a fourth means in which a buffer tank and a buffer check valve are provided at a stage upstream of the vacuum pump in the piping, so that the inside of the buffer tank during vacuum suction is provided. An object of the present invention is to provide a vacuum suction method characterized in that the buffer check valve is closed when the gas pressure exceeds the evacuation capacity of the vacuum pump.
According to the fifth means, when the gas pressure in the buffer tank exceeds the evacuation capacity of the vacuum pump during vacuum suction, suction gas is prevented from flowing into the vacuum tank and the degree of vacuum is prevented from decreasing, Vacuum suction cycle time can be shortened.

According to the present invention, since the sucked gas is discharged first, the deterioration of the vacuum degree in the vacuum tank is less than when all the gas is sucked and diffused in the vacuum tank, and the vacuum level is reached in a short time. degree can be reached.
In addition, the time required to vacuum the vacuum tank and reach the maximum vacuum level can be shortened, reducing the time required for one cycle (cycle time) of die-casting machines, etc. If so, a higher degree of vacuum can be maintained. Therefore, the vacuum pump can be made smaller than before, which can contribute to cost reduction.

FIG. 2 is an explanatory diagram of a vacuum device of the present invention. FIG. 3 is an explanatory diagram of a vacuum device according to modification 1; FIG. 7 is an explanatory diagram of a vacuum device according to modification 2; It is an explanatory view of a suction part of a modification. FIG. 2 is an explanatory diagram of a conventional vacuum device.

Embodiments of the vacuum device and vacuum suction method of the present invention will be described in detail below with reference to the drawings.

[Vacuum device 10]
FIG. 1 is an explanatory diagram of a vacuum apparatus of the present invention. As shown in FIG. 1 (1), the vacuum device 10 of the present invention includes a vacuum pump 14 that has a vacuum tank 12 and sucks and discharges gas in the cavity, and piping 16 that connects the exhaust passage of the cavity and the vacuum pump 14. It is equipped with
The piping 16 includes a suction part 18 having a large cross-sectional area in the middle (the suction part 18 shown in FIG. 1 is cylindrical), and rectifies the gas sucked into the suction part 18 toward the exhaust passage (in this embodiment). In the configuration, rectification refers to a state in which the flow of sucked gas is made to flow forcefully in a straight line), and a hopper 22 is provided on the side of the vacuum pump 14 to collect the rectified gas. ing.
A straight pipe 20 passes through the suction part 18 at one end face on the exhaust passage side, and a hopper 22 is attached to the other vacuum pump 14 side.
The straight tube 20 is a straight tube of a predetermined length, and has a distal end extending within the suction section 18 . The length of the straight tube 20 (a in FIG. 1) is set so that the gas sucked from the cavity can be rectified in a straight line so as not to diffuse.

The hopper 22 is arranged in the extending direction of the straight tube 20. The hopper 22 shown in Fig. 1 has a funnel-like shape and is arranged coaxially with the straight pipe 20, but the positional relationship is not limited to this and may be eccentric (see Fig. 1 (5)). ). The side of the hopper 22 with a larger cross-sectional area is arranged near the tip of the straight pipe 20, and the side with a smaller cross-sectional area is connected to the piping 16 on the vacuum pump 14 side. Such a hopper 22 can converge the gas that has passed through the straight pipe 20 and become rectified within the suction section 18 without diffusing it, and guide it into the piping 16 on the vacuum pump 14 side.
Note that the hopper 22 is not limited to a funnel-like shape as long as it has the function of guiding the gas rectified by the straight pipe 20 to the vacuum pump 14. As another form, the hopper 22 may be formed into a stepped funnel shape. FIG. 4 is an explanatory diagram of a modified example of the suction section. As shown in FIG. 4, the hopper has an integral structure with a large cross-sectional area similar to the suction part 18A, and the vacuum pump 14 side has a stepped shape (1) or a cylinder shape (when the cross-sectional area is large, the hopper is connected to the vacuum pump 14). Connecting structure) (2) may be formed.

The vacuum tank 12 is branched and connected to the suction section 18 . The branch connection point of the vacuum tank 12 is set at a side surface point closer to the exhaust passage than the tip of the straight pipe 20 in the suction section 18. As shown in FIG. 1B, the tip of the straight tube 20 and the opening of the branched part of the vacuum tank 12 are set so as not to overlap when viewed from the side of the suction section 18. Such a configuration prevents the gas sucked from the cavity within the suction section 18 from flowing toward the vacuum tank 12 and diffusing.
FIG. 1(2) shows a cross-sectional view AA at the position b in FIG. 1, where the tip of the straight tube 20 and the opening of the branched part of the vacuum tank 12 do not overlap when viewed from the side of the suction part 18. As shown in the drawing, the cross-sectional area The area difference is set to be sufficient so as not to take too much time, and to allow the suction gas that cannot be discharged to quickly flow into the vacuum tank 12 if the vacuum pump 14 exceeds its capacity during vacuum suction. ing.

Here, the cross-sectional area of the suction part 18 is X (see Figure 1 (2)), the cross-sectional area of the straight pipe 20 is Y (see Figure 1 (2)), and the cross-sectional area of the suction port of the vacuum pump 14 is Z (see Figure 1 (2)). (1)), and when the cross-sectional area of the connecting portion between the vacuum tank 12 and the suction part 18 is W (see FIG. 1 (1)), the following relationship needs to be satisfied.
The cross-sectional area of the straight tube 20 needs to be large enough to allow the vacuum device 10 to exhibit sufficient exhaust capacity when performing vacuum suction.
The relationship between the cross-sectional area X of the suction part 18 and the cross-sectional area Y of the straight tube 20 needs to satisfy (X-Y)≧Y, that is, X≧2Y. In this way, the suction section 18 needs to have an area that is more than twice that of the straight tube 20.
The relationship between the cross-sectional area Z of the suction port of the vacuum pump 14 and the cross-sectional area Y of the straight pipe 20 (with respect to the flow path to the vacuum pump 14) needs to satisfy Z≧Y.
The relationship among the cross-sectional area X of the suction part 18, the cross-sectional area Y of the straight tube 20, and the cross-sectional area W of the connection part between the vacuum tank 12 and the suction part 18 (with respect to the flow path to the vacuum tank 12) is (X-Y )≦W. Note that the larger (XY) is, the more suction gas that exceeds the exhaust capacity of the vacuum pump 14 can be made to flow into the vacuum tank 12 side during vacuum suction in a short time.
In addition, the cross-sectional shape of the straight tube 20 is not limited to a circular shape, and may be an ellipse or a polygonal hollow shape (FIGS. 1 (3) and (4) show the case where the cross-sectional shape of the straight tube 20 is a square). show).
Note that the cross-sectional shape of the suction portion 18 is not limited to a cylindrical shape, but may also be an elliptical or polygonal hollow shape. Following the shape of the suction part 18, the shape of the hopper 22 is also similar, and the side with a larger cross-sectional area is placed near the tip of the straight pipe 20, and the side with a smaller cross-sectional area is connected to the piping on the vacuum pump 14 side. (FIGS. 1(4) and 15(5) show the case where the cross-sectional shape of the suction portion 18 is square).

[Vacuum suction method]
The vacuum suction valve 11 of the pipe 16 is closed, and the vacuum tank 12 is brought to the highest degree of vacuum using the vacuum pump 14. When pressurizing the molten metal into the cavity in the injection process, the vacuum suction valve 11 is opened and the molten metal is press-fitted at high pressure simultaneously with vacuum suction. The gas sucked from the exhaust passage of the cavity is rectified in a straight line by a straight pipe 20, suppressing diffusion within the suction section 18, collected by a hopper 22, and discharged to the atmosphere by a vacuum pump 14. In this way, the gas in the cavity is suctioned within the suction section 18 to temporarily generate a region with a low degree of vacuum, minimizing the diffusion toward the side of the vacuum tank 12 that is branch-connected to the suction section 18, and from this region. The vacuum pump 14 actively exhausts the air to the atmosphere. Therefore, compared to conventional methods, a high degree of vacuum can be maintained in the vacuum tank 12 after the vacuum suction operation is completed, and the vacuum tank 12 can reach the maximum degree of vacuum in a short time, reducing the cycle time. This makes it possible to contribute to the reduction of

[Example]
As an example, when the tank capacity of the vacuum tank 12 was 1000 liters and the amount of air to be sucked was 26 liters, the time until the vacuum tank 12 reached the maximum degree of vacuum was measured. As a result, compared to the conventional configuration (shown in FIG. 4), the vacuum apparatus 10 of the present invention was able to achieve a 25% reduction in time.
According to the present invention, since the sucked gas is discharged first, the degree of vacuum in the vacuum tank 12 is less likely to deteriorate compared to when all the gas is sucked and diffused in the vacuum tank 12. The highest degree of vacuum can be reached in a short time.

[Modification 1]
FIG. 2 is an explanatory diagram of a vacuum device according to modification 1. As shown in the figure, the vacuum device 10A of Modification 1 employs a configuration in which a suction section, in other words, a straight pipe 20 and a hopper 22 are provided inside a vacuum tank 12A. The tip of the straight tube 20 is disposed inside the end surface of the hopper 22 on the side with a larger cross-sectional area so that the sucked gas does not diffuse from the inside of the hopper 22 to the vacuum tank 12A.
According to the vacuum device of Modification 1, the entire device can be downsized.

[Modification 2]
FIG. 3 is an explanatory diagram of a vacuum device according to modification 2. As shown in the figure, the vacuum device 10B of Modification 2 has a buffer tank 30 and a buffer check valve 32 installed between the suction section 18 and the vacuum pump 14.
The buffer tank 30 has an internal space with a predetermined capacity smaller than that of the vacuum tank 12, and is provided with a buffer check valve 32 at its end on the suction section 18 side. The buffer check valve 32 is a ball-type valve that allows suction gas from the exhaust passage side of the cavity to pass through and prevents backflow of gas from the vacuum pump 14 side. Note that the structure of the buffer check valve 32 is not limited to this, and any structure that can prevent backflow of gas from the vacuum pump 14 side may be used. can also be applied.
The vacuum tank 12 is branched and connected to the suction section 18 as in the configuration shown in FIG. 1, and further connected to the buffer tank 30 via a bypass pipe 34. A valve 36 is provided on the bypass pipe 34, and pressure gauges 38, 40 are provided in the buffer tank 30 and vacuum tank 12.

In the vacuum device 10B of Modification 2 having such a configuration, first, the vacuum suction valve 11 is closed and the vacuum pump 14 performs vacuum suction. At this time, when the pressure gauge 38 of the buffer tank 30 is below the specified pressure, the valve 36 of the bypass pipe 34 is opened and vacuum suction is performed until the vacuum tank 12 reaches the maximum degree of vacuum. After confirming that the vacuum tank 12 has reached the maximum degree of vacuum using the pressure gauge 40 of the vacuum tank 12, the valve 36 of the bypass pipe 34 is closed.
Next, the vacuum suction valve 11 is opened to vacuum the gas inside the cavity. The gas sucked from the cavity is rectified by the straight pipe 20 in the suction part 18, collected in the hopper 22 in the suction part 18, and enters the buffer tank 30 by opening the buffer check valve 32 (by pushing up the ball). , and are exhausted to the atmosphere by the vacuum pump 14. When the amount of gas sucked during vacuum suction exceeds the exhaust capacity of the vacuum pump 14 and the internal pressure inside the buffer tank 30 rises, the ball is pushed back toward the suction part 18 and the buffer check valve 32 is closed. This prevents suction gas from flowing into the vacuum tank 12 and lowering the degree of vacuum when the gas pressure in the buffer tank 30 exceeds the exhaust capacity of the vacuum pump 14 during vacuum suction, thereby reducing the vacuum suction cycle time. Can be shortened.
Note that filters are preferably attached to the exhaust passage side of the piping 16 and the vacuum pump 14 side. This can prevent foreign matter from entering the cavity during vacuum suction.

The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.
Moreover, the present invention is not limited to the combinations shown in the embodiments, but can be implemented by various combinations.

2 Mold 3 Filters 1, 10, 10A, 10B Vacuum device 11 Vacuum suction valves 12, 12A Vacuum tank 14 Vacuum pump 16 Piping 18, 18A Suction part 20 Straight pipe 22 Hopper 30 Buffer tank 32 Buffer check valve 34 Bypass pipe 36 Valve 38 Pressure gauge 40 Pressure gauge

Claims (5)

A vacuum pump that has a vacuum tank and sucks and discharges gas in the cavity;
comprising piping connecting the exhaust passage of the cavity and the vacuum pump,
The piping includes a straight pipe for rectifying the gas sucked into the exhaust passage side, and a hopper for collecting the rectified gas toward the vacuum pump side. A vacuum device characterized in that the sucked gas is first discharged before the gas flows into the vacuum tank and diffuses . The vacuum device according to claim 1,
A vacuum device characterized in that the straight pipe of the piping and the hopper are provided inside the vacuum tank. The vacuum device according to claim 1 or 2 ,
A vacuum device comprising a buffer tank provided between the hopper and the vacuum pump, and a buffer check valve that closes when the gas pressure in the buffer tank exceeds the exhaust capacity of the vacuum pump. In a vacuum suction method, the gas inside the cavity is suctioned and discharged using a vacuum pump equipped with a vacuum tank to reduce the pressure inside the cavity to a vacuum state,
In a pipe that connects the exhaust passage of the cavity and the vacuum pump and includes a straight pipe for rectifying the gas sucked into the exhaust passage side and a hopper for collecting the rectified gas on the vacuum pump side , A vacuum suction method characterized in that when the gas is sucked in a vacuum state, the sucked gas is discharged first before the gas flows into the vacuum tank and diffuses . The vacuum suction method according to claim 4 ,
A buffer tank and a buffer check valve are provided in the piping upstream of the vacuum pump, and when the gas pressure in the buffer tank exceeds the exhaust capacity of the vacuum pump during vacuum suction, the buffer check valve closes the pipe. A vacuum suction method characterized by:

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