JPS6049067B2 - sand molding method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mold making method, particularly a sand mold making method such as a blow ink method or a vacuum method, in which a sand mold is manufactured using a gas flow.

Conventionally, there are various methods for manufacturing sand molds using green sand, such as a gas mold method (CO2) and a shell mold method. For example, to explain the latter, as shown in Figures 5 and 6, metal models 2, 2 are fixed on a surface plate 1, and sand is prevented from entering the surface plate 1 located around the model 2. A large number of ventilation passages 3, 3 having a diameter must be provided in accordance with the shape of the model. Furthermore, a cover body 4 is attached to seal the outside of the model 2. A space 5 corresponding to the thickness of the sand mold is provided in the cover body 4, and a blowing port 6 for blowing sand is provided in the cover body 4. Next, to make a mold, the model 2 is heated, and sand mixed with a thermosetting resin such as phenol resin is blown into the space 5 inside the cover body 4 through the blowing port 6. Natural exhaust is released from the small exhaust holes 3, 3 provided around the model 2, and at that time, the sand carried by the gas flow is deposited around the model 2, and then the model 2 is heated to form a sand mold. It is completed by curing. This shell mold method is often used to manufacture precision casting parts of various types, but it requires many small holes to be made on the surface plate to match the shape of the model, which is extremely time-consuming and When the shapes are different, there is a drawback that the surface plate cannot be used repeatedly. Moreover, depending on the shape of the model, the position where the small holes 3 are provided is restricted, and air dams are likely to occur within the cover body 4. As a result of air dams occurring within the cover body, there were cases in which the sand did not fill every corner of the model. Therefore,
As shown in FIG. 7, a missing portion 10 was formed in the ridgeline portion 9 of the completed sand mold 8, and the finished product was likely to be defective. In particular, if this missing part 10 occurs on the cutting surface of the upper mold and the lower mold, the two cannot be matched accurately, resulting in misalignment,
There was a drawback that the finished molded products were defective. In view of these conventional drawbacks, the present invention prevents the airflow containing plowed or vacuumed sand from forming an air dam inside the cover body, and allows the airflow to flow smoothly, thereby depositing sand densely around the model. The structure consists of a first step in which a large number of small-diameter air passages are provided vertically and horizontally in the cutting surface of the mold model in communication with each other, and a pair of air passages are placed facing each other. A second step of fixing the cut surfaces of the mold model on the surface plate by communicating the air passages with exhaust holes provided through the surface plate, and forming a space between the surface plates. A third step of fixing a housing having a gas inlet at the upper part between the surface plates, a fourth step of fixing a cover body having an outlet through a space outside the surface plate, and an inlet of the housing. The fifth step consists of forcibly supplying sand mixed with a hardening substance from the inlet and at the same time forcibly exhausting gas from the outlet.

A large number of ventilation passages are provided at appropriate intervals around the edges of the mold model, which is mounted on the surface plate with its cut side in close contact with each other. Because the sand is sucked in from the road, the sand is densely deposited around the mold model, making it possible to form a sand mold that accurately inverts the mold model.

Examples of the present invention will be described below with reference to the drawings.
Reference numeral 1 denotes metal surface plates placed facing each other, and one or more exhaust holes 12, 12 are provided at appropriate locations to penetrate them.
In order to create a closed chamber 17 between the surface plates 11, 11, a housing 18 is fixed to the outside of the surface plates. This housing 18
There is sand on the top. An inlet 19 is provided through which a gas containing a curing agent flows in by plowing or vacuum. 2
Reference numerals 0 and 20 denote cover bodies attached to the outside of the surface plates 11 and 11, with spaces 21 and 21 provided between them and the surface plates, respectively. Outlets 22, 22 for discharging the water are provided respectively.

The cut surfaces 14, 14 cut in half from the cut line of the mold model are connected at each intersection at right angles or diagonally, so as to form a U-shaped cross section and prevent sand grains from entering. Ventilation passages 15, 15 with a diameter of
5 and 15 respectively on the surface plate 11.
, 11.

In this case, the exhaust holes 12, 12 are made to match any intersection of the ventilation passages 15. Note that each of the outlet ports 22 is connected to a known exhaust device (shown) or a negative pressure generator (not shown) for forced exhaust. The term "mold model" here is a broad concept that includes models of molded products, core models, runner models, and formwork models for forming the outer peripheral edges of sand molds that match each other. Although not shown in the drawings, some mold models may be constructed so that the mold model or the mold model and the surface plate can be heated from the outside.

To explain the second example of the mold model, mold model 2
A peripheral edge part 26 of a constant width is provided at the peripheral edge part of the body cutting surface 24 of No. 3, and U-shaped ventilation passages 25 are formed in the vertical and horizontal directions inside the peripheral edge part 26 of the body cutting surface 24, and each ventilation passage communicates with each other. Provide intersections for each. Among the ventilation passages 25 provided vertically and horizontally across the entire fillet surface, the portion located within the peripheral edge 26 is formed into a small diameter passage 27 to prevent sand from being sucked in, and the ventilation passage located at the center of the fillet surface is formed in the large-diameter passage 28 in order to improve gas circulation efficiency. Next, to explain the operation, in the state shown in Fig. 1, sand mixed with thermosetting resin such as phenol resin and other hardening substances is passed through the inlet 19 into the empty chamber 1 along with air and other harmless gases.
When forced into or sucked into the mold model 13, the airflow containing sand particles passes through the numerous ventilation channels 15 provided around the periphery of the mold model 13.
15, exhaust hole 12, space 21, outlet 22
is emitted into the atmosphere. In this case, the mold model 13 or the mold model 13 and the surface plate 11 are heated by externally applied heat to harden the sand mold, or the sand mold can be hardened by hardening other hardenable substances. Vacancy 17
Since the air passage 15 communicating with the air passage 15 has a small diameter, almost no sand particles will enter the air passage 15, and even if a small amount of sand does enter, no problem will occur. As described above, the present invention provides a large number of ventilation passages on the cutting surface of the mold model, so that air dams are not created in the housing and the air is smoothly discharged to the outside. It is possible to form accurately, center the upper and lower molds accurately, and form the edge of the sand mold accurately, which prevents defective products when producing precision and fine castings. In addition, when installing the mold model on the surface plate, there is no need for a spacer so that the mold model can be attached tightly, making installation easier.Furthermore, the surface plate can be used repeatedly, further improving work efficiency. It has beneficial characteristics.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a cross-sectional view of the entire device with some parts omitted, FIG. 2 is a front view of the cutting surface of the mold model, FIG. 3 is a plan view of the same, and FIG. is a front view showing the cut surface of a mold model in another embodiment, FIGS. 5 to 7 show a conventional device, and FIG. 5 is a cross-sectional view just before sand is blown into
FIG. 6 is a partially omitted plan view of a mold model, and FIG. 7 is a partially cutaway perspective view of a sand mold manufactured by a conventional method. 11 is a surface plate, 12 is an exhaust hole, 13 is a mold model, 14 is a cut surface, and 15 is a ventilation path.

Claims (1)

[Claims] 1. A first step in which a mold model is cut into two parts, and a large number of vertical and horizontal ventilation passages with small diameters that prevent sand from entering are connected to each other on each cut surface, and a pair of ventilation passages are arranged facing each other. A second step of fixing the cut surfaces of the mold model on the surface plates by communicating the exhaust holes provided through the respective surface plates with a part of the ventilation passage, and a second step of fixing the cut surfaces of the mold model on the surface plates, and a step between the facing surface plates. In order to form a closed room, a third step is to fix a housing having a gas inlet at the top between the surface plates, and fix a cover body each having an outlet through a sealed space outside the surface plate. A sand mold making method comprising a fourth step, and a fifth step of elastically supplying sand mixed with a hardening substance from the inlet of the housing, and at the same time forcibly exhausting gas from the outlet.