JP2003039154A - Degassing method and degassing device for mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a degassing device effectively producing a casting not causing entrainment of gas and a shrinkage cavity by disposing a pressure pin installable in a place small in space and servicing also as degassing to direct pressurize a mold cavity. SOLUTION: The degassing device for a mold for squeeze casting, wherein a molten metal is filled in the mold cavity by an injection device from a gate part disposed below the mold, and a final filling place is direct pressurized, is constituted so as to be provided with a pressure pin provided with a seal part on the tip and a gas passage communicating with the mold outside on the rear from the tip part, a driving part driving the pressure pin, a pressure pin control part controlling the pressure pin, and a sensor part detecting the filling state of the molten metal in the mold cavity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a degassing method and a degassing apparatus for a mold used for squeeze casting in which a molten metal level in a cavity is kept horizontal and uniform by vertical casting. The present invention relates to a mold degassing method and a degassing device for degassing the inside of a mold cavity at the time of injection filling by a pressurizing pin that directly pressurizes the final filling position.

[0002]

2. Description of the Related Art Conventionally, as for the technique of extracting the gas from the mold and pressurizing the molten metal with a pressurizing pin, for example, JP-A-8-281409, JP-A-9-300057 and JP-A-7- No. 232259, JP-A-8-
The one described in 1972228 has been put into practical use.
JP-A-8-281409 and JP-A-9-300
The technology described in Japanese Patent No. 057 is as follows. A spiral hot water reservoir is provided on the dividing surface in the degassing passage leading from the cavity to the outside, and a hole with a diameter smaller than the inner diameter of the hot water reservoir is provided at the center of the hot water reservoir at a right angle to the dividing surface. A pressure pin having a gas vent groove extending in the axial direction on the rear outer surface is provided slidably in the hole, and the hot water reservoir and the gas vent groove are disconnected from each other at the forward and backward limit positions of the press pin. The passage to be obtained was provided between the inner peripheral surface of the tip of the hole and the outer peripheral surface of the pin. Using this device, when the pin is moved forward while the molten metal is being filled so that the hot water tank and the gas vent groove communicate with each other to discharge the gas, the centrifugal force in the spiral hot water pool causes the molten metal to enter the gas vent groove. It is described that, before the completion of filling, the pin is retracted to block the pool and the gas vent groove, and the pressurizing pin is advanced again when the molten metal solidifies and contracts to exert the feeder force. There is.

On the other hand, the techniques described in JP-A-7-232259 and JP-A-8-197228 are as follows. A cylindrical nesting stem mounted on a crosshead mounted on a cylinder built in the movable plate is slidably provided inside the movable mold with the tip end facing the cavity. It is described that a hydraulic device that can increase the hydraulic pressure acting on the head chamber of the cylinder after the pouring operation is completed is used to vent gas from the gap around the nest stem.

[0004]

The above-mentioned conventional techniques have various problems. That is, JP-A-8-281
In the techniques described in Japanese Patent Application Laid-Open No. 409 and Japanese Patent Application Laid-Open No. 9-300057, a molten metal reservoir is provided outside the mold cavity in parallel with the mold dividing surface, and the mold is located at a position away from the mold cavity (product portion). A pressure pin is provided in the direction perpendicular to the mold dividing surface. Therefore, the effect of pressing the molten metal is less than that in the case of directly pressurizing the inside of the cavity. In addition, since a hot water tank is provided, the required space becomes large,
It is not possible to freely select the place where you want to raise the water. Therefore, in many cases, the pressure pin cannot be installed at the final filling position.

Next, in the techniques described in JP-A-7-232259 and JP-A-8-1972228, since the core pin is mounted concentrically with the center pin, only the gas can be discharged from the center. ing. Therefore, according to this technical idea, it was not possible to install a pressure pin also serving as a gas vent at an arbitrary position, that is, a final filling position.

The present invention has been made in view of the above-mentioned problems, and a purpose thereof is to serve as a gas vent which can be installed even in a place where it is difficult to install a conventional gas vent device due to a small space. A die degassing method and gas for efficiently producing a cast product having no gas entrapment and having no shrinkage cavity by arranging a pressure pin and directly pressurizing the final filling point of the die cavity To provide a removing device.

[0007]

In order to achieve the above object, in the first invention, the molten metal is filled into the mold cavity by an injection device from a gate portion arranged in the lower part of the mold and pressurized. In a squeeze casting method for degassing a mold in which the final filling point is directly pressed by a pin, a pressing pin having a seal portion at the tip and a gas passage communicating with the outside of the die behind the tip portion is provided in the die cavity. It was arranged at the final filling position inside to directly pressurize the inside of the mold cavity and degas the inside of the cavity.

Further, in the second invention, for squeeze casting in which the molten metal is filled in the mold cavity by the injection device from the gate portion arranged in the lower part of the mold and the final filling portion is directly pressed by the pressing pin. In the mold degassing device,
A pressure pin having a seal portion at the tip and a gas passage communicating with the outside of the mold behind the tip portion, a pressure pin drive unit for driving the pressure pin, and a pressure pin for controlling the pressure pin. The control unit and the sensor for detecting the filling state of the molten metal in the mold cavity are provided.

Recently, in order to make a cast product having a complicated shape,
Many casting dies use slide cores (also called movable cores). In addition, since there are many cast products with uneven wall thickness, it is necessary to partially press the thick wall portion. Furthermore, when a slide core is used, a drive device is also required, and when partial pressure is applied, cooling / temperature control piping is also required, and it has been difficult to install the conventional gas venting method in terms of space. On the other hand, degassing the inside of the cavity is effective by performing it from the final filling position. This final filling point differs depending on the product shape. Therefore, the degassing device should be as compact as possible. For this reason, the tip of the pressure pin has a seal structure (minimum gap within which the pressure pin can slide), and a gas passage is formed in the pressure pin behind the seal structure. It is possible to perform a degassing function with almost the same size as the pressure pin. As described above, since the present invention can exhibit the function as the pressurizing pin and the degassing device, even if the space is small and it is difficult to install the conventional degassing device, the final filling part is determined by the CAE analysis (melt flow analysis). It is possible to estimate and arrange a pressure pin in this final filling part. Depending on the shape of the product, if there is no place to pressurize the product part, it is possible to add a surplus and arrange a pressurizing pin also serving as a gas vent in that part. Such a degassing method can be applied even when it is necessary to attach a partial pressure mechanism to the slide core. In this way, by directly pressurizing the mold cavity, it is possible to provide a mold degassing method and a degassing apparatus that efficiently produce a cast product without gas entrapment and without shrinkage cavities. .

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION In a casting mold, a partial pressure pin is often provided at a place where shrinkage cavity is predicted to occur. A method and apparatus for degassing using this partial pressure mechanism will be described. First, the configuration of the degassing device according to the embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG. 2 shows a state in which the slide core 1 is attached above the mold apparatus 10 and the mold is clamped. The slide core 1 is vertically movable by a slide core driving cylinder 12. A pressure pin 2 is inserted in the slide core 1 so as to be movable back and forth, and is driven by a hydraulic cylinder 3 via a pressure plate 6. On the other hand, the tip portion 14 of the pressure pin 2 is inserted into the pressure pin insertion hole 13 of the slide core 1 with a minimum slidable gap. When the pressurizing pin 2 is moved forward by the hydraulic cylinder 3, a gas vent passage 8 is formed as shown in FIG. Since the gas vent passage 8 communicates with the outside of the mold, it is possible to vent gas in the cavity when the pressurizing pin is in the forward position.

Next, the operation procedure of the present invention will be described. First, the final filling position in the cavity is confirmed by CAE flow analysis, and the degassing device according to the present invention is arranged in this part. Next, as shown in FIG. 1, the pressurizing pin 2 also serving as a gas vent according to the present invention has a tip portion 14 having a sealing structure, and a space (communication between the mold cavity and the atmosphere is provided rearward (upper) from this portion). A gas passage) 8 is provided. In this embodiment, a portion having a smaller diameter than the seal portion is provided, but only a portion may be deepened to form a groove. next,
The operation procedure of the present invention will be described based on FIGS. 1 and 2. (1) The mold device 10 is brought into a mold open state. (2) As shown in FIG. 2, the slide core 1 is attached to the mold device 1
Assemble into 0 and clamp the mold. (3) The pressurizing pin 2 is moved forward to the forward limit so that the inside of the mold cavity communicates with the atmosphere (outside the mold). (4) The molten metal is injected and filled in the mold cavity by an injection device (not shown). (5) A sensor (not shown) detects that the injection stroke has reached a preset value during injection filling, and sends this detection signal to a pressure pin controller (not shown). The pressure pin control unit receives this detection signal and retracts the pressure pin. At this time, the signal for retracting the pressurizing pin may be a time-out signal depending on the elapsed time from the start of injection instead of the signal sent from the sensor. (6) After the pressure pin retreat is completed, the pressure pin advance stopper 4 is inserted. The height H of the pressure pin advance stopper 4 is adjusted so that the die cavity and the atmosphere do not communicate with each other even if the pressure pin 2 advances to the limit of advance. (7) After that, after the molten metal is completely filled in the cavity, the pressure pin 2 is advanced again. (8) Hold the above state for a preset pressurizing time. (9) After retracting the pressure pin 2, the pressure pin advance stopper 4 is retracted. (10) Further, although the pressurizing pin 2 may adjust the forward moving speed to a low speed, the backward moving speed needs to be always returned to a high speed, so the forward moving speed is adjusted by a flow control valve with a check valve (not shown). (11) After the elapse of a predetermined cooling time, the mold is opened and the product is taken out. As described above, from step (1) to step (1
By repeating 1), it is possible to efficiently produce a cast product without gas entrapment and without shrinkage cavities.

[0012]

As is apparent from the above description, since the present invention has the structure as set forth in the claims, it can function as a pressure pin and a degassing device.
It can be installed even in a place where it is difficult to install the conventional degassing device due to the small space. Therefore, by directly pressurizing the mold cavity, it is possible to efficiently produce a cast product without gas entrapment and without shrinkage cavities.

[Brief description of drawings]

FIG. 1 is a detailed view of a slide core portion according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a mold device incorporating a slide core according to an embodiment of the present invention.

[Explanation of symbols]

1 slide core 2 pressure pin 3 hydraulic cylinder 4 Pressurizing pin advance stopper 5 Air cylinder 6 pressure plate 7 Pressure pin controller 8 degassing passage 9 Pressure pin drive 10 Mold equipment 12 Slide core drive cylinder 13 Pressure pin insertion hole 14 Pressure pin tip H Stopper height

Claims (2)

[Claims] 1. A degassing method for a squeeze casting mold, in which a molten metal is filled into a mold cavity by an injection device from a gate portion arranged at a lower part of the mold and a final pin is directly pressed by a pressure pin. A pressure pin having a seal part at the tip and a gas passage communicating with the outside of the mold behind the tip is provided at the final filling point in the mold cavity, and the inside of the mold cavity is directly A method for degassing a mold, which comprises pressurizing and degassing the inside of the cavity. 2. A squeeze casting mold degassing device for filling molten metal into a mold cavity by means of an injection device from a gate portion arranged at a lower part of the mold and directly pressurizing a final filling portion with a pressure pin. And a pressure pin having a seal portion at the tip and a gas passage communicating with the outside of the mold behind the tip portion, a pressure pin drive unit for driving the pressure pin, and controlling the pressure pin. A degassing device for a die, comprising: a pressurizing pin control section; and a sensor for detecting a filling state of the molten metal in the die cavity.