JPS6331298B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method and apparatus for casting a mold for press or injection molding.

Conventional technology Conventionally, when precision casting molds for press molding or synthetic resin injection molding, a ceramic mold with a ceramic layer laid on the inner bottom surface of the casting was used to precisely cast the details. It was getting worse.
However, if the shape of the casting, that is, the mold, is complex,
Precision casting of molds with casting dimensions of 600 mm or more will inevitably cause warping, so the tolerance at the end of casting may be ±
Casting within 0.3 mm/m was difficult. Therefore, the method generally adopted to solve this problem is to create a scaled-up reference model in the first step, taking into account the shrinkage rate, and then, in the second step, to cast a first ceramic mold from the reference model. In the third step, the first ceramic mold is measured and the erroneous values of the deformed parts are reflected in the standard model.The positive parts are cut from the standard model, and the negative parts are raised from the standard model to form a corrected model.
Then, in the fourth step, a second ceramic mold is cast from this revised model, this second ceramic mold is further measured to calculate the error value, and the revised model is revised again in the same manner as above, and this revised model is used to calculate the error value. Third
A ceramic mold was made, and this third ceramic mold was used for casting to complete a predetermined precision mold.

Problems to be Solved by the Invention The cause of the deformation of the final finished product, that is, the mold, is due to the thermal contraction of the cast metal and the mold during the cooling process from the casting temperature to room temperature. There was a problem that the amount was different, and this difference became resistance, causing errors in the completed mold.

In order to eliminate the conventional problems, the present invention aims to ensure that when pouring molten metal into a mold, the mold has sufficient strength.
Once the solidification of the cast metal material is complete and the shape of the casting is frozen, the strength of the mold is released to allow each part of the casting to contract freely, allowing the casting to contract naturally and preventing abnormal deformation. This invention aims to cast high-precision cast products.

Means for Solving the Problems The present invention detects the solidification completion temperature of the casting material A by a temperature sensor 1 disposed inside the casting material A when precision casting a mold, and at the time of detection, the temperature at which the solidification of the casting material I is completed is detected. Gap holes 4 and 5 are instantaneously formed along the side wall 2a and the portion of the ceramic mold 3 (hereinafter simply referred to as the mold) that receives the shrinkage force generated during solidification of the casting material A, and the core mold 2 and the mold are The mold is cast by instantly lowering the lateral pressure strength in Step 3.

Function According to the method of the present invention, when the solidification of the casting material A is completed, the temperature at which the solidification is completed is detected by the temperature sensor 1, and the gap holes 4, which are instantaneously formed in the core mold 2 and the mold 3 by this detection. 5 eliminates the strength of the core mold 2 and the mold 3, and absorbs the shrinkage force generated when the casting material A solidifies.

Embodiment Example 1 of the present device is shown in FIG. 1, and will be explained about a mold for casting a die for a press mold made of steel or cast iron. The core mold 3 is a mold which accommodates the casting material A and into which the core mold 2 is fitted. A sprue 6a is bored in the center of the upper mold 6, and a passage 6b communicating with the conventional upper gap hole 4 is bored around the periphery, and the upper end of the passage 6b is connected to a discharge pipe connected to a vacuum device. 7 is connected. Core mold 2
When the upper mold 6 is superimposed on the core mold 2, the inner mold 6 is placed along the side wall 2a through a small distance l from the side wall 2a, that is, along the side that receives the shrinkage force generated when the casting material A solidifies. An upper gap hole 4 communicating with the passage 6b is bored in the upper gap hole 4. Inside the mold 3, which has a ceramic layer 8 attached to the inner bottom surface, there is a protruding side wall 3b on the bottom 3a side of the part that receives the shrinkage force generated toward the center when the casting material A solidifies during casting.
A lower gap hole 5 is bored along the bottom part 3a.
A discharge passage 9 communicating with the lower gap hole 5 is bored in the lower gap hole 5, and the discharge passage 9 is connected to an external vacuum device.

When casting according to Example 1, the core mold 2 and the upper mold 6 are superimposed on the mold 3, and the passage 6b, the upper gap hole 4, and the lower gap hole 5 are filled with dry sand, respectively. Further, pouring molten metal from the sprue 6a to fill the space between the core mold 2 and the mold 3 with a casting material I, and embedding a temperature sensor 1 connected to a computer inside the casting material I, Boost water is poured into the sprue 6a. Then, the solidification of the casting material A begins, the temperature sensor 1 detects the solidification completion temperature, and the electric signal is input to the computer connected to the temperature sensor 1, and the vacuum device B is activated by the command from the computer. When the dry sand in each part is sucked out through the discharge pipes 7 and 9, the upper gap hole 4 and the lower gap hole 5 become voids. on the other hand,
The shrinkage force toward the center of the casting material A, which is being cooled, is exerted by pressing the side wall 2a of the core mold 2 and the protrusion side wall 3b of the mold 3, and crushing the upper gap hole 4 and the lower gap hole 5. It gets absorbed.

Next, Example 2 will be explained about the female mold (cavity) of the synthetic resin injection mold shown in FIG. 2, which is made of copper, zinc alloy, and aluminum and is cast at a casting temperature of 1000 degrees or less. 6 is an upper mold, and 3 is a mold with a ceramic layer 8 attached to the inner bottom surface.
A space 3c is formed on the bottom 3a side of the mold 3 along the protrusion side wall 3b at a distance l, and an aluminum plate 10 as a heat conduction jig is formed in the space 3c along the protrusion side wall 3b. A lead plate 11 with a thickness of 6 mm is provided in parallel, the aluminum plate 10 is connected to a cartridge heater 12, a molten lead tray 13 is provided below the lead plate 11, and the cartridge heater 12 is protected. It is connected to a computer and a power source outside the mold 3 via a frame 14.

When casting according to the second embodiment, the mold 3 is injected with molten metal and filled with the casting material A, and at the same time is connected to a computer machine. After embedding the temperature sensor 1, an upper mold 6 is placed on the mold 3. and,
As in Example 1, the solidification completion temperature of the casting material A is detected and the electrical signal is input to the computer, which then controls the cartridge heater 1.
When a power input command is issued to 2 to heat the aluminum plate 10, the lead plate 11 attached to the aluminum plate 10 is melted. The molten lead melts and flows down into the molten lead receiving tray 13 below, and after flowing down, a gap is created along the protrusion side wall 3b of the mold 3. Due to the generation of this gap, the strength of the mold is reduced, and the protruding side wall 3b of the mold 3 is pushed toward the gap by the contraction force of the casting material acting toward the center.
is crushed to form a mold.

Effect According to the present invention, when the casting material completes solidification, a gap is created inside the mold along the side wall of the mold where the shrinkage force generated in the casting material acts, so the strength of the mold is released and the casting material is weakened. The contraction force acts toward the center and crushes the side walls of the mold toward the gap,
The shrinkage force is absorbed, the casting material contracts naturally, and it is possible to cast a high-precision mold with extremely little warpage.

[Brief explanation of drawings]

Fig. 1 is a sectional view of a mold of Example 1 in which a press die is cast by this method, and Fig. 2 is a cross-sectional view of a mold of Example 2 in which a female die of a synthetic resin injection mold is cast by this method. 3 is a cross-sectional view of the mold in Example 2 in which lead has melted and gaps have been created. Code, 1... Temperature sensor, 2... Core mold, 2a
...Side wall, 3...Ceramic mold, 3a...Bottom, 3b
... Projection side wall, 3c... Space, 4... Upper gap hole (gap), 5... Lower gap hole (gap), 6... Upper mold, 6a...
Sprue gate, 6b...passage, 7...discharge pipe, 8...ceramic layer, 9...discharge pipe, 10...aluminum plate, 11...lead plate,
12... Cartridge heater, 13... Molten lead saucer, 14... Protective frame, l... Spacing, B... Casting device, B... Vacuum device, C... Dry sand, D... Computer, H... Power source, H... L... Molten lead.

Claims (1)

[Claims] 1. Temperature sensor 1 disposed inside the casting material A.
Detects the solidification completion temperature of the casting material A, and instantaneously forms a gap 4 of several millimeters to more than ten millimeters along the core mold 2, the side wall 2a, or the side wall of the ceramic mold 3 based on the detected signal. A method for casting a precision mold, characterized in that the mold is formed by 2. An upper gap hole 4 and a lower gap hole 5 are bored inside the core mold 2 or the ceramic mold 3 along the side wall 2a or the protrusion side wall 3b with a small distance 1 from the side wall 2a or the protrusion side wall 3b. A precision mold casting device characterized in that the upper gap hole 4 and the lower gap hole 5 are connected to a vacuum device via discharge pipes 7 and 9. 3. A lead plate several millimeters thick is attached to the aluminum plate 10 inside the core mold 2 or ceramic mold 3 along the side wall 2a or the protrusion side wall 3b through a small gap from the side wall 2a or the protrusion side wall 3b. 11
are provided in parallel, the aluminum plate 10 is connected to the cartridge heater 12, a molten lead tray 13 is provided below the lead plate 11, and the cartridge heater 1
2 is a precision mold casting device characterized by being connected to a computer and a power source.