JPH02104439A - Method for forming casting mold - Google Patents

Abstract

PURPOSE:To improve dimensional accuracy without deforming a casting mold in a transporting stage of the casting mold or at the time of pouring molten metal by ramming molding sand by an upper molding board provided with projected lines engaging with the ends of a recessed hole bored to the molding sand section in the upper part of a pattern. CONSTITUTION:Molding flasks 3a, 3b are imposed on the lower molding board 2 having the pattern 1 and the molding sand 4 is charged into the molding flasks 3a, 3b. The molding sand 4 is leveled off to approximately the same height as the plane of the molding flask 3b. The recessed hole 5 is thereafter bored into the molding sand 4 section in the upper part of the pattern 1 and the molding sand 4 is pressed and rammed by the upper molding board 7 provided with the projected lines 6 engaging with the ends of the recessed hole 5. The molding sand 4 charged between the projecting lines and the molding flasks 3a, 3b is first rammed and further, the molding sand 4 is rammed until the surface of the molding sand 4 is made flush with the base of the hole 5. The molding sand 4 is thereafter rammed by the pattern 1 and the upper molding board 7 with the projecting lines 6 as a boundary if the entire part of the horizontal surface of the molding sand 4 is pressed by the entire part of the upper molding board 7. The molding sand 4 is thus rammed to the approximately uniform hardness. The casting mold is produced when the molding flask 3b is removed after the above-mentioned ramming.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to an improvement in a mold making method.

(Prior art and problems to be solved) Conventionally, after a casting flask is placed on a lower surface plate having a model, casting sand is poured into the flask, and the mold is cast on a flat upper surface plate or protruding from the periphery. Molding is done by compacting the casting sand using an upper surface plate having sand pressing pieces (for example, Japanese Utility Model Application Publication No. 134728/1983), but the casting sand does not have a uniform hardness, and the casting sand above the top of the model is hard;
Since the casting sand near the flask is soft, there is a problem in that the mold deforms during the mold transport process or during pouring.

Therefore, the present invention has been made to solve such problems, and provides a mold manufacturing method that is less likely to cause T4 type deformation.

(Means for Solving the Problems) The present invention involves drilling a concave hole in the casting sand area above the model, and applying the casting sand using an upper surface plate provided with a convex strip that engages with the end of the concave hole. This is a mold making method that hardens the mold.

(Function) Since the present invention has the above-described configuration, when the upper surface of the casting sand having the concave holes is pressed by the upper surface plate provided with the convex stripes, the casting sand initially put between the convex stripes and the casting flask is pressed. is compacted, and when the upper surface plate presses the entire horizontal top surface of the sand control, the sand control is compacted by the model and the upper surface plate along the convex stripes, and is also compacted by the lower surface plate and the upper surface plate. It is hardened and the anti-sand property becomes approximately uniform in hardness.

(Example) Figures 1 and 2 show a molding method according to the present invention, in which flasks 3a and 3b are placed on a lower surface plate 2 having a model 1,
, insert the sand protection 4 into the mold 3b, cut the sand into the sand protection 4 to approximately the same height as the surface of the flask 3b, and then drill a recessed hole 5 in the sand protection 4 part above the model 1. The sand control 4 is pressed from above by an upper surface plate 7 provided with a protrusion 6.6 that engages with the sand control 4 to compact it. In addition, the shape of the protrusion 6.6 can be changed as appropriate,
The flask 3b represents a joint frame.

The upper surface of the sand protection 4 having the recessed hole 5 is covered with an upper chamber m having a convex strip 6.6.
7, the sand protection 4 initially inserted between the convex strips 6.6 and the flasks 3a, 3b is compacted, and the sand protection 4 is further compacted.
After compacting the sand protection 4 surface to the same height as the bottom of the hole 5, press the entire top surface of the horizontal sand protection 4 with the entire upper surface plate 7.
The sand protection 4 is tamped by the model 1 and the upper surface plate 7 with the protrusions 6 and 6 as boundaries, and is also tamped by the lower surface plate 2 and the upper surface plate 7, so that the sand protection 4 has approximately uniform hardness. .

Thereafter, when the flask 3b is removed, a mold as shown in FIG.

(Effect of the invention) According to the present invention, a concave hole is bored in the sand prevention part above the model,
Since the sand protection is compacted by the upper surface plate provided with a protruding strip that engages with the end of the recessed hole, the sand protection becomes approximately uniform in hardness, and mold deformation does not occur during the transport process of the mold or during pouring. Castings with good dimensional accuracy are produced.

In addition, the simple structure of providing a convex strip on the upper surface plate and drilling a recessed hole in the top surface of the sand barrier makes the sand barrier approximately uniform in hardness, which simplifies the molding equipment and makes maintenance easier. Become. Furthermore, the anti-sand grooves formed by the ridges on the upper surface plate can be used as gas vent holes.

[Brief explanation of the drawing]

1 and 2 are cross-sectional views showing a molding apparatus according to the present invention, and FIG.
The figure is a sectional view showing a mold made according to the present invention. 1...Model, 4...Sand control, 5...Concave hole, 6...
Convex strip, 7... Upper surface plate.

Claims (2)

[Claims] (1) In a mold making method in which a casting flask is placed on a lower surface plate with a model, casting sand is poured into the flask and the sand is compacted by the upper surface plate, a recessed hole is formed in the casting sand area above the model. 1. A mold making method, which comprises: drilling a hole, and compacting the casting sand using an upper surface plate provided with a protruding strip that engages with the end of the recessed hole. (2) Casting sand is poured into a casting flask equipped with a joint frame, and the sand is cut to approximately the same height as the joint frame. After that, a recessed hole is drilled in the casting sand area above the model, and the end of the recessed hole is A mold making method characterized by compacting the casting sand using an upper surface plate provided with protrusions that engage with the parts, and then removing the joint frame.