JPS6340283Y2 - - Google Patents

Description

[Detailed explanation of the idea]

<Industrial Application Field> The disclosed technology belongs to the technical field of the structure of green sand molds that prevent the occurrence of burrs and the like in cast products having hollow parts. Therefore, this invention has a structure of a green sand mold for casting, for example, a cylinder block having a hollow part of an automobile engine, and has a cavity formed between an outer mold and a core, and has an outer mold. This is a device related to a green sand mold structure in which a leakage prevention part is provided in the gap that occurs in the mating surface formed between the mold and the core to prevent the occurrence of burrs, etc. This invention relates to a green sand mold structure in which a nest having a V-shaped groove is removably attached to the side of the runner forming part of the surface. <Prior Art> As is well known, the nature of green sand molds used for casting causes gaps in the mold mating surfaces to cause burrs on the product, and therefore various operations are required after the product is manufactured. The causes of the gap mentioned above include shrinkage of the core, buoyancy of the molten metal, distortion of the upper and lower metal frames, deformation of the mold, etc., but it has traditionally been impossible to eliminate the gap by taking all factors into consideration. It was hot. In particular, in recent years, as casting technology has progressed, core technology has developed and the structure of the product has become more complex. Along with this, the problem that the above-mentioned gaps produce a large number of burrs on products has become too large to be ignored. To deal with this, for example,
As disclosed in the patent publication, grooves are integrally formed on the surface of the outer mold using a grinder and milling to form protrusions on the sand mold, and gaps that occur on the mating surfaces when inserting the core etc. Green sand molds have been adopted in which the above-mentioned gaps are eliminated by using green sand, molds, mold seals, or hot expansion putty. <Problems to be solved by the invention> However, in the case of the former, since the outer mold and the groove are integrally processed, there is a drawback that the necessary groove dimensional accuracy cannot be secured. Furthermore, since the groove dimensions cannot be changed, it is difficult to conduct evaluation tests for optimum dimensions. In addition, the latter method has the disadvantage that the number of work steps increases, leading to an increase in costs. <Purpose of the invention> The purpose of this invention is to solve the problems of the green sand mold structure based on the above-mentioned conventional technology as a technical problem, and of course to prevent burrs from forming on the product due to gaps in the mold mating surfaces. It is an object of the present invention to provide an excellent green sand mold structure that can be freely adjusted according to the size of the gap, thereby benefiting the field of application of casting technology in the machine manufacturing industry. <Means and actions for solving the problems> In order to solve the above-mentioned problems, the structure of this invention, which is based on the scope of the above-mentioned utility model registration claims, is based on the above-mentioned purpose. By attaching a nest having a groove of a predetermined size to a recess formed on the mold surface of the mold and forming a cavity in the upper and lower sand molds, a protrusion can be formed in the part of the runner corresponding to the groove. Therefore, if the core is supported by the cavity and the mold is clamped, the above-mentioned protrusions protrude into the gap formed on the mold mating surface with respect to the core, thereby preventing the leakage of the melt. A technical measure has been taken in which the child is detachable so that a protrusion of a desired height can be freely formed. <Example> Next, an example of this invention will be described below based on the drawings. The embodiment shown in FIGS. 1 and 2 (FIG. 2 is a sectional view of FIG. 1) is a green sand mold 1 that forms the center of the gist of this invention, and is used for manufacturing cylinder blocks of automobile engines. A lower mold 3 and an upper mold 3' made of molding sand are set between the lower metal frame 2 and the upper metal frame 2' so as to form upper and lower casting molds, and the molds are matched together. It is being done. Therefore, inside the lower mold 3 and upper mold 3', there is a core 4.
is set, the core 4 is composed of a rear core 44, a front core 45, a water jacket core 46, a slab core 47, a crank core 48, etc.

【table】

[Table] ○: No leakage ×: Leakage Also, the dimensions of the depth d and width W of the groove 16 (horizontal axis)
, leakage failure rate C ₁ (%), mold breakage failure rate C ₂ (%)
(vertical axis) is shown in FIG. 6, it has been found that as the leakage failure rate _C1 decreases, the mold breakage failure rate _C2 increases. From the above results, the dimensions of the groove 16 of the insert 17 are shown in the table, and the dimensions of type B in the table are d = 3.0 and W = 3.0.
was found to be the optimal size. Therefore, when manufacturing the green sand mold 1, after installing the insert 17 of the optimum size into the recess 15 of the outer mold 11, the lower metal frame 2 and the upper metal frame 2' are installed, and the green sand of the casting sand is used to lower the mold. When the mold 3 and the upper mold 3' are formed and the core 4 is installed, the V-shaped protrusion 18 formed on the lower mold 2 is inserted into the groove 16 of the insert 17 installed in the recess 15 of the outer mold 11.
is inverted into green sand and protrudes into a gap (not shown) formed on the molding surface with the flank core 48, and acts as a kind of barrier to prevent the molten metal flowing through the runner 8 from leaking. This prevents the occurrence of burrs. In addition, since the V-shaped protrusion 18 is formed,
When the protrusion 18 collapses, it collapses from the narrow part on the tip side with respect to the lower mold 3, and the destructive effect on the lower mold 3 is also small. Since the protrusions 18 are provided along the runner 8, it is also possible to prevent product defects from occurring due to changes in the hot water circulation caused by hot water leaks. It goes without saying that the embodiment of this invention is not limited to the above-mentioned embodiment, and for example, the groove shape is not limited to a V-shape, and various other embodiments can be adopted. <Effects of the invention> As described above, according to this invention, the mold matching surfaces of the outer mold and the core of each part are basically affected by the core shrinkage of the green sand mold in which the core is set, the buoyancy of the molten metal, the distortion of the metal frame, etc. Even if a gap occurs, the protrusion formed by the groove of the insert can block the gap and eliminate leakage, resulting in the excellent effect that it is possible to manufacture products without burrs. is played. In addition, by removably attaching an insert having a groove of a depth corresponding to the above gap to the mold surface of the outer mold, the grooves of the insert can be machined separately from the outer mold, resulting in high dimensional accuracy. In addition, when changing the groove dimensions, an evaluation test for the optimum dimensions can be carried out freely, so an excellent effect can be achieved in that an insert that completely prevents leakage of hot water can be used. Therefore, not only can optimal evaluation tests be carried out during product manufacturing after the initial design has been determined, but evaluation tests can also be applied flexibly to changes in the dimensions of the outer mold and core over time during use due to wear, etc. This has an excellent effect of preventing the occurrence of burrs due to water leakage due to subsequent continued use. In addition, there is an advantage that casting defects are reduced and costs can be reduced accordingly.

[Brief explanation of the drawing]

The drawing shows one embodiment of this invention,
Figure 1 is a longitudinal sectional view of the green sand mold, Figure 2 is a sectional view of Figure 1, Figures 3 and 4 are a plan view of the outer mold and its sectional view, and Figure 5 is a perspective view of the insert. , FIG. 6 is a graph showing the relationship between the groove dimensions of the insert, the mold breakage failure rate, and the melt leakage failure rate. 11... Outer mold, 4... Core, 5... Cavity, 3, 3'... Green sand mold, d... Depth, 17...
...Neriko.

Claims (1)

[Claims for Utility Model Registration] (1) It has a cavity formed between an outer mold and a core, and a leakage prevention part is formed in the gap generated in the mating surface formed between the outer mold and the core. In the green sand mold structure provided, an insert having a groove having a depth corresponding to the gap is removably attached to the side of the runner forming part on the mold surface of the outer mold. Green sand mold structure. (2) The green sand mold structure according to claim 1, wherein the groove is formed in a V-shape.