JPH0243557Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to an extrusion pin for a casting die, and is capable of measuring the gas pressure inside the die cavity during casting.

(Prior art) As part of measures to prevent casting defects, holes are made inside the mold cavity to measure the gas pressure inside the mold cavity during casting, and a porous body with pores, such as a sintered vent A known method is to attach a mold to the hole, provide a passage isolated from the outside air from behind the sintering vent, and guide the gas inside the mold to a gas pressure sensor to measure the gas pressure.

(Problems to be solved by invention) In this conventional method, a special hole 61 was made in the mold as shown in FIG. There are two main problems in this case. The first problem is that it is necessary to make many holes in the mold for gas passages. Normally, it is necessary to provide holes for extrusion pins and holes for cooling water in the mold vertically and horizontally. Moreover, complex molds are made of a combination of inserts, and such holes must be provided vertically and horizontally for the mold and the mold insert. Providing extra holes for gas passages in the mold shortens the life of the mold. Moreover, special drilling of such holes involves an increase in extra machining steps.

The second problem is that traces of sintering vents may remain on the product surface. If aesthetic appearance is required, the product must be subjected to post-processing.

The purpose of this invention is to solve the problems of the conventional gas pressure measurement method in a mold as described above, and to provide a device that can measure the gas pressure in a mold without performing any special processing on the mold. It is something to do.

(Means for solving problems by invention) The extrusion pin of the present invention has a cylindrical ventilation hole with a diameter of 10 to 50 μm and a dense and smooth inner wall surface at the end of the extrusion pin on the side that forms the cavity in a die-casting mold. A sintered vent having a large number of is pressed into the pin, and a pressure transducer is provided in the opening.

As the molten metal is filled into the casting mold, the gas pressure inside the mold increases. Particularly in the die casting method, the pressure of the molten metal reaches several 100 kg/cm ² or more. This increased pressure is passed through a porous body with many thin holes that allow the gas to pass through but not the molten metal, and is guided from behind through a gas introduction path to, for example, a piezo gas pressure sensor, where it is converted into an electrical signal. In the method of measuring gas pressure by converting the gas pressure, the above object of the present invention can be achieved by incorporating the porous body mounting part and the gas introduction path into the pressing pin.

When the molten metal poured into the mold solidifies and is removed as a casting, when the split mold is opened, the casting sticks to one of the molds. At this time, in order to separate the casting from the mold, a plurality of ejector pins are pushed out through the ejector pin holes using a push plate provided on the back side of the mold. A plurality of ejector pins are installed over almost the entire surface of the casting to prevent excessive local force from being applied to the casting. It is also desirable to install multiple units in the mold cavity when determining the gas pressure inside the mold cavity. Therefore, by incorporating gas introduction channels into the extrusion pins that are distributed over the entire surface of the mold cavity, there is no need to make special holes in the mold for gas pressure measurement, and it is possible to The remaining traces are only the number of extrusion pins, and the number does not increase. Furthermore, if it is no longer necessary to know the gas pressure inside the mold cavity, it can be easily replaced with a normal ejector pin. Note that a porous sintered body can generally be used as the porous body.

This is made by sintering metal powder, ceramic powder, etc., and has many ventilation holes. This allows gas to pass through, but not molten metal. It is preferable that the ventilation holes are in a straight line.
There is one described in Publication No. 51-31210. This sintered vent has many straight ventilation holes with a diameter of 0.01 to 0.5mm, and the walls of the ventilation holes are made dense and smooth by the infiltrated material, allowing gas to pass through easily but not molten metal. It has a unique structure. In die casting molds, the molten metal is injected under high pressure, so the diameter of the vent hole is 0.01 to 0.05 mm (10 to 50 μm).
It is desirable to do so.

In order to arrange the porous body on the push-out pin, for example, the porous body is previously fitted, sintered or welded into a sleeve having the same diameter as the porous body. In FIG. 5, a screw 10 is cut on the outside of the sleeve 9, and in FIG. 6, a screw 10' is cut on the inside of the sleeve, so that they can be freely attached to and removed from the push-out pin 1. In Fig. 5, some of the screws are left uncut, and a ring with the same outer diameter as the ejector pin is left in that part to be freely inserted and removed.When attaching the sleeve to the ejector pin, the ring is Remove and screw in, then fit the ring.

In the case shown in FIG. 7, a gentle taper is formed in the porous body, a similar taper is provided in the communication hole 11 of the extrusion pin, and the porous body is fitted and held.

In FIG. 8, a groove 13 for brazing is provided on the outer contact end surface of the sleeve 9 and the push-out pin, and brazing is performed. This wax has a melting point higher than that of the molten metal used.

As the porous body, metal powder or sintered bodies of various ceramic powders are selected and used depending on the purpose of use. For example, for pouring light alloys such as aluminum die casting, a sintered body of iron (steel) powder may be used.

(Example) FIG. 1 shows an example of the configuration of the push-out pin of the present invention.
A communication hole 11 and a large diameter hole 12 are provided at the center of the extrusion pin 1.
A gas pressure sensor 4 is connected to the conduit 3 leading to the hole.
is installed, and the signal from the gas pressure sensor passes through a conductor 5, a width gauge 6, a conductor 7, and reaches a measuring device 8. A sintering vent 2, which is a porous body, is installed in the large-diameter hole 12 at the tip of the extrusion pin, which is provided with pores that do not allow molten metal to pass through, but allow gas to pass through. Further, the entire area of the holes 11, 12 and the conduit 3 serves as a gas introduction path, and is made airtight so that gas does not leak from the middle.

For example, some gas pressure sensors utilize changes in resistance due to the piezoresistance effect, in which a strain gauge part is formed directly on the surface of a silicon diaphragm using a diffusion layer using an IC fabrication method, and the pressure is proportional to the minute strain that occurs in this diaphragm. is detected as a voltage. The material of the ejector pin 1 is mainly made of steel so that it can withstand the pressure and temperature of the molten metal and the pressure when taking out the product. The sintering vent 2 is made of iron and has an operating temperature of 700°C, so that it can withstand the temperature and pressure of the molten metal. It is convenient to use a pipe made of metal such as steel or stainless steel as the conduit 3.

(Experiment example) Applied to an aluminum die-casting mold. Six important locations of the ejector pins distributed over the entire surface of the mold were selected and replaced with the ejector pins of the present invention, and the gas pressure inside the mold was measured. The ejector pin performed its original function of ejecting the product, and was also able to measure the gas inside the mold.

The material of the extrusion pin was stainless steel, the conduit 3 was a stainless steel pipe, and the connection between the extrusion pin and the conduit was brazed with silver solder to maintain airtightness.

As shown in Figure 1, the sintered vent has an average particle size of 150
It is made by sintering mesh steel powder with copper as an infiltration material, and has approximately 1,500 pores of 50 μm in the center, allowing gas to pass through but not molten metal.

The inner diameters of the conduit 3 and the hole 11 are both 3 mm in diameter. The wall thickness of the conduit is 0.5 mm and the length is approximately 300 mm.

As the gas pressure sensor 4, a piezo pressure transducer was used.

The outer dimensions of the sintered vent are 6mm in diameter and 10mm in length.
mm, and is made to have the same dimensions as the hole 12 of the extrusion pin, and is fitted into the large diameter hole 12 with a clearance of about 0.1 to 0.2 mm.

During aluminum die casting, we were able to measure the cavity pressure without having to drill a hole in the mold body to install a pressure transducer. An example of measurement is shown in FIG.

(Functions and Effects) The ejector pin according to the present invention has the performance of a normal ejector pin for ejecting the casting from the die-casting mold, and also guides the gas inside the mold through a specific sintering vent built into the ejector pin. A gas pressure sensor can measure the gas pressure inside the mold.

In particular, even in die casting where the molten metal pressure is several 100 kg/cm ² or more, the gas pressure inside the cavity can be measured stably and accurately for a long period of time. Based on this accurate measurement result, it is possible to control casting conditions in response to actual conditions, thereby reliably preventing various casting defects.

Therefore, there is no need to provide an extra hole for gas pressure measurement in the die-casting mold, the number of man-hours for manufacturing the mold is reduced, and the life of the mold and the beauty of the product are not degraded.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing an embodiment of the present invention, Fig. 2 is a cross-sectional view showing the state in which the extrusion pin of the present invention is attached to a mold, Fig. 3 is a cross-sectional view showing a conventional pressure measurement state, and Fig. 4 The figure is a diagram showing the pressure measurement results in the experimental example, Figures 5 and 6 are cross-sectional views showing the state in which the sleeve is attached to the extrusion pin, and Figure 7 shows the state in which the sintered vent is attached to the extrusion pin. cross section,
FIG. 8 is a sectional view showing the state in which the sleeve is attached to the push-out pin. 1... Extrusion pin, 2... Porous body, sintered vent, 11... Communication hole.

Claims (1)

[Scope of utility model registration request] In the die-casting mold, a sintered vent with a large number of cylindrical ventilation holes with a diameter of 10 to 50 μm and a dense and smooth inner wall surface is placed at the end of the extrusion pin on the side that forms the cavity. A communication hole communicating with the opening provided on the other end face of the extrusion pin and having a diameter smaller than the maximum dimension of the cross section of the sintered vent is provided in the extrusion pin, and a pressure transducer is provided in the opening. An extrusion pin that is characterized by its shape.