JP2016002551A - Manufacturing method of casting - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a further improved manufacturing method of a casing, capable of maintaining a filling state of molten metal, by quickly preventing a backflow of the molten metal filled in a product cavity, in the manufacturing method of the casting for coagulating by filling the molten metal in a desired cavity part, by sending compressed gas from a sprue part, before filling the poured molten metal in the desired cavity part, by pouring the molten metal of the volume smaller than the whole volume of a casing mold cavity and almost equal to the desired cavity part, for filling the molten metal in the desired cavity part that is a part among cavities of a ventilating casting mold.SOLUTION: A manufacturing method comprises a cooling process of coagulating or semi-coagulating by cooling at least a part of molten metal existing in a molten metal flow passage in preference to the molten metal filled in a product cavity, and the cooling process supplies a cooling object having fluidity via a supply hole formed in a different position from the sprue part so as to contact with at least a part of the molten metal existing in the molten metal flow passage.

Description

  The present invention relates to a method for producing a cast article.

  As a method for producing a cast article, a casting mold using sand particles as a breathable mold, that is, a gravity casting method using a so-called sand mold is most commonly applied. When such a breathable mold (hereinafter, the breathable mold is sometimes referred to as a mold) is used, the remaining air is pushed out from the cavity surface when the molten metal is filled into the cavity of a specific shape. The entire cavity is filled with molten metal (hereinafter sometimes referred to as molten metal), and a casting having the same shape as the cavity can be obtained. The mold cavity generally has cavities such as a sprue part, a runner part, a feeder part, and a product part, and the molten metal supplied from the spout part flows in this order. In the conventional technique, the molten metal is poured into the sprue portion disposed at the height of the molten metal head sufficient to fill the product portion (hereinafter, the product portion may be referred to as a product cavity), and the casting is finished. .

  When the casting article solidified in this way is seen, the gate part, runner part, feeder part and product part are connected as a casting. Here, the feeder part is a cavity set for the soundness of the product and is not an unnecessary part, but the sprue part and runner part are only flow paths for supplying molten metal to the product part. In other words, it is an essentially unnecessary part. Therefore, as long as the molten metal is solidified in the gate or runner, the injection yield cannot be significantly improved. In addition, if the casting is formed by connecting unnecessary parts, it takes a considerable number of man-hours for sorting the product part and the unnecessary part in the separation process of the product part, which is a subsequent process, and the production efficiency is lowered. For this reason, in the gravity pouring method, the presence of a gate and a runner as a casting has been a big problem.

  Recently, an epoch-making technique for the above-described problem is disclosed in Patent Document 1 below. In the technique disclosed in Patent Document 1, the entire volume of a mold cavity is filled in order to fill a desired cavity portion that is a part of a cavity of a gas-permeable mold (hereinafter sometimes referred to as a mold cavity). The molten metal having a volume smaller than that of the desired cavity portion is poured, and before the poured molten metal is filled into the desired cavity portion, a compressed gas is supplied from the gate portion to obtain the desired cavity portion. The molten metal is filled and solidified (hereinafter, this method may be referred to as an air supply and pressure casting method). According to this air supply pressure casting method, the required pressure is compensated for by the height of the molten metal head, so that the molten metal in the molten metal flow path as well as the molten metal flow path is almost unnecessary. It is expected to be possible.

  In addition, Patent Document 2 discloses that the molten metal is used for the purpose of shortening the completion time of filling the melt into a desired cavity portion while being based on the air-feeding pressure casting method disclosed in Patent Document 1. Before filling the desired cavity portion, the additive material is fed into the cavity from the gate, and the molten metal poured is filled into the desired cavity portion, and the additive material (specifically, refractory particles and A casting method in which at least a part of the other cavity portion is filled with (metal particles) is disclosed.

JP 2007-75862 A JP 2010-269345 A

  The present inventors conducted experiments in order to realize the air-feeding pressure casting method described in Patent Document 2. As a result, for example, when a foreign matter trapping filter is disposed in the molten metal flow path such as a runner leading to the product cavity, or when the molten metal flow path is a complicated mold, It was found that the additive fed from the part may not be filled reliably. In this case, the molten metal once filled in the product cavity is pushed back by the head pressure and flows backward, so that the filled state of the molten metal into the product cavity cannot be maintained, and a normal cast article cannot be obtained. Recognized that there is.

  The present invention has been made in view of the above-described problems of the prior art, and in the manufacturing method of a cast article to which the air supply and pressure casting method is applied, the backflow of the molten metal filled in the product cavity is quickly prevented and An object of the present invention is to provide a more improved method for producing a cast article that can maintain a filling state.

  One aspect of the present invention that achieves the above object is a molten metal supply step of supplying a molten metal from the gate to the molten metal flow path that is sufficient to fill at least a part of the product cavity and the molten metal flow path among the cavities of the air-permeable mold. Then, a molten metal filling process for filling the product cavity with the molten metal by feeding gas from the spout and pushing the molten metal in the molten metal flow path, and at least a part of the molten metal present in the molten metal flow path And a cooling step of solidifying or semi-solidifying by cooling preferentially over the molten metal filled in the product cavity, wherein the cooling step is present in the molten metal flow path. This is a method for manufacturing a cast article that supplies a coolant having fluidity through a supply hole formed at a position different from the pouring gate so as to touch at least a part of the molten metal.

  In the above embodiment, the cooling object is preferably a metal sphere, a metal particle, a metal piece, or other metal medium.

  Further, in the above embodiment, the supply hole is a bottomed hole, and a part of the breathable mold is interposed between the bottom surface of the supply hole and the molten metal flow path. It is desirable to pump the cooling material so as to break a part of the breathable mold.

  In addition, in the cooling step, it is more preferable to supply the coolant through a supply hole provided on the product cavity side from the rear end portion of the molten metal existing in the molten metal flow path.

  According to the present invention, in the manufacturing method of a cast article to which the air supply and pressure casting method is applied, the improved casting in which the back flow of the molten metal filled in the product cavity is quickly prevented and the molten state is maintained. It is possible to provide a method for manufacturing an article.

It is a figure explaining each process of the manufacturing method of the cast article of one embodiment concerning the present invention.

  Hereinafter, the present invention will be described based on an embodiment thereof with reference to the drawings. The embodiment described below is the most preferable embodiment. That is, the present invention does not necessarily require all the constituent elements of the embodiments described below, and as long as the effects of the present invention are exhibited, the constituent elements can be implemented singly or in combination as appropriate. It can be implemented with deformation.

  As described in the section of the means for solving the above problems, the method for manufacturing a cast article shown in FIG. 1 as an embodiment according to the present invention includes at least a product cavity 10b and a molten metal flow among the cavities 10a of the mold 10. A molten metal supply step (see FIG. 1 (a)) for supplying the molten metal M sufficient to fill a part of the passage 10c into the molten metal flow path 10c from the sprue part 10f composed of the sprue cup part 10d and the introduction gutter part 10e. Next, a melt filling step (see FIG. 1B) for filling the product cavity 10b with the molten metal M by feeding the gas G from the gate portion 10f and pushing the molten metal M in the molten metal flow path 10c, and the molten metal flow There is a cooling step (see FIG. 1C) in which at least a part M1 of the molten metal M present in the passage 10c is preferentially cooled and solidified or semi-solidified over the molten metal M filled in the product cavity 10b. It is a manufacturing method of creation goods. And in the said cooling process, as shown in FIG.1 (c), it formed in the position different from the said gate part 10f so that at least one part M1 of the molten metal M which exists in the said molten metal flow path 10c might be touched. A coolant C having fluidity is supplied through the supply hole 10g. In addition, although the feeder 10 is not formed in the casting_mold | template 10 shown in FIG. 1, you may provide as needed for the purpose of suppression of a shrinkage nest. The molten metal channel 10c is specifically a concept including the gate portion 10f and the runner portion 10h, but is not limited thereto, and may be a channel in which the molten metal M leading to the product cavity 10b flows.

  According to such a method for producing a cast article, the following effects can be obtained. That is, in the molten metal supply step shown in FIG. 1A, at least a part of the product cavity 10b and the molten metal flow path 10c among the cavities 10a of the breathable mold 10 supplied to the molten metal flow path 10c through the gate portion 10f is filled. In the molten metal filling step shown in FIG. 1 (b), the molten metal M that is sufficient is filled in the product cavity 10b by being pushed by the gas G fed from the gate 10f. In the cooling step shown in FIG. 1 (c), at least a part M1 of the molten metal M present in the molten metal flow path 10c is preferentially cooled over the molten metal M filled in the product cavity 10b to be solidified or semi-solidified. Solidify. As a result, a part M1 of the molten metal M that has been preferentially cooled and solidified or semi-solidified has a plug shape, and is directed in the direction of the gate 10f of the molten metal M filled in the product cavity 10b (the direction opposite to the gas flow). Backflow can be suppressed. In order to achieve such a backflow suppression effect, at least a part M1 of the molten metal M present in the molten metal flow path 10c is solidified or semi-solidified (hereinafter, both may be collectively referred to as solidification). Of course, of course, almost all of the molten metal M present in the molten metal flow path 10c may be solidified.

  Furthermore, in the cooling process of the present embodiment, the cooling material C as a cooling medium is used to cool and solidify at least a part M1 of the molten metal M, and the cooling material C is a part M1 of the molten metal M. Supply to touch. Here, the coolant C is supplied through a supply hole 10g formed at a position different from the gate 10f. That is, the coolant C is supplied so as to touch a part M1 of the molten metal M through the supply hole 10g which is a path different from the molten metal flow path 10c constituted by the gate part 10f, the runner part 10h, and the like. . Accordingly, the coolant C is reliably supplied to a part M1 of the molten metal M to be solidified regardless of the plan of the molten metal channel 10c and the presence or absence of the foreign matter capturing filter in the molten metal channel 10c. it can. As a result, a part M1 of the molten metal M that has come into contact with the coolant C is solidified reliably, and the backflow of the molten metal M filled in the product cavity 10b is suppressed with higher accuracy. The coolant C refers to a cooling medium containing at least a solid content, and does not include a cooling medium composed only of gas or liquid.

  Further, the coolant C that cools and solidifies at least a part M1 of the molten metal M has fluidity. The point of imparting fluidity to the coolant C in this way is effective in the sense that it is not necessary to strictly control the start timing of the cooling process with respect to the molten metal filling process. That is, the start time of the cooling process can be set not only after the end time of the melt filling process but also before the end time of the melt filling process. That is, as in the latter case, when there is a time when the molten metal filling process and the cooling process are parallel, the cooling process is started in a state where the molten metal M is not completely filled in the product cavity 10b, and the molten metal flow path 10c. Even if the coolant C is supplied to a part M1 of the molten metal M present in the steel, the coolant C does not hinder the fluidity of the melt M pushed by the gas G because the coolant C has fluidity. The molten metal M smoothly flows in the molten metal flow path 10c and is filled in the product cavity 10b. Then, after the filling of the molten metal M into the product cavity 10b is completed, as explained above, a part M1 of the molten metal M present in the molten metal flow path 10c is solidified by the coolant C, and the inside of the product cavity 10b The backflow of the molten metal M is prevented.

  As the coolant C having fluidity as described above, a particulate cooling medium such as refractory particles may be used, but metal spheres, metal particles, metal pieces, or other metal media should be used. Is desirable in that the cooling of the molten metal M can be further promoted. Furthermore, it is more desirable to use a medium composed of the same chemical composition as that of the molten metal M because it is difficult for foreign components to be mixed into a cast article obtained as a product and the composition of the composition hardly changes. The particle size, particle size distribution, and supply amount of the medium that is the cooling object C may be appropriately set in consideration of the size of a part M1 of the molten metal M that exists in the molten metal channel 10c to be solidified.

  Although the form and arrangement of the supply hole 10g for supplying the coolant C are not particularly limited, as shown in FIG. 1, the supply hole 10g is a bottomed hole, and between the bottom surface of the supply hole 10g and the molten metal flow path 10c. It is preferable that a part 10 i of the mold 10 is interposed in the mold 10. In this way, the supply hole 10g is a bottomed hole, and the bottom surface of the supply hole 10g is arranged at a certain distance from the inner peripheral surface of the molten metal flow path 10c, whereby the molten metal flow path 10c (runner section 10h) is formed. The fluidity of the flowing molten metal M is not hindered, and the molten metal M pushed by the gas G is smoothly filled into the product cavity 10b. In this way, when the supply hole 10g is a bottomed hole, in the cooling process, as shown in FIG. 1 (c), the coolant C may be supplied by being pumped so as to break a part 10i of the mold 10. Good.

  As an aspect of the supply hole 10g, an inorganic or metallic tubular member may be arranged in the mold 10 to form the supply hole. However, it is desirable for industrial production in terms of cost to directly drill the mold 10 with a drill or the like to form the supply hole 10g directly in the mold 10. Further, when the mold 10 is a green sand mold and the supply hole 10g is directly formed by drilling in the mold 10, the strength of the supply hole 10g is maintained and damage during handling is suppressed. For example, a coating coat may be applied to the inner peripheral surface and the bottom surface. Further, the supply hole 10g does not need to be disposed above the molten metal flow path 10c (runner channel portion 10h), and may be disposed so as to face the molten metal flow path 10c so that the bottom surface thereof faces the molten metal flow path 10c. .

  Further, the position of the supply hole 10g in the horizontal direction is not particularly limited as long as the coolant C can touch a part M1 of the molten metal M in the molten metal flow path 10c. For example, in order to further increase the injection yield obtained by dividing the product weight by the pouring weight, the rear of the molten metal M existing in the molten metal flow path 10c in the state where the molten metal M is filled in the product cavity 10b. The position of the supply hole 10g in the horizontal direction may be set so that the coolant C touches the rear end face M2 exposed on the side (pouring gate 10f side), more desirably the rear end face M2. However, as shown in FIG. 1 (c), the supply hole 10g is provided closer to the product cavity 10b than the rear end face M2 of the molten metal M present in the molten metal flow path 10c. It is desirable to supply C. The reason is that the coolant C is reliably supplied to a part M1 of the molten metal M present in the molten metal flow path 10c regardless of the position fluctuation of the rear end face M2 of the molten metal M due to the variation in the amount of molten metal poured in the molten metal supply process. This is because the part M1 can be solidified and the backflow can be reliably prevented.

  Hereinafter, the specific configuration of the method for manufacturing a cast article according to this embodiment will be described in more detail.

  The mold 10 used in the manufacturing method of the present embodiment is a green sand mold obtained by molding casting sand formed by mixing sand, caking additive (such as bentonite), moisture, carbon powder and the like. The breathable mold is not limited to the green sand mold, and for example, a mold formed using sand particles, ceramic particles, or metal particles constituting a shell mold, a self-hardening mold, or the like can also be used as the breathable mold. In addition, even if the material is almost non-breathable, such as gypsum, it can be used as a breathable mold by mixing with breathable materials or by using a breathable material partially to create sufficient breathability. Can be used. Further, even a mold using a material having no air permeability such as a mold can be used as a gas permeable mold when other air holes such as a vent hole are provided to provide air permeability. .

  As shown in FIG. 1 (a), a mold 10 which is a green sand mold has an upper mold 10m formed in an upper frame 10j and a lower mold 10n formed in a lower frame 10k. Are arranged on the surface plate 10L. A mold cavity 10a formed by matching the upper mold 10m and the lower mold 10n is a pouring part 10f composed of a pouring cup part 10d and an introduction gutter part 10e, a runner part 10h, and a final product. On the other hand, it is comprised by the product cavity 10b formed in the shape to which the appropriate surplus thickness was added, and each is connected in this order.

  As shown in FIG. 1 (a), the pouring cup portion 10d that forms the pouring gate portion 10f is a portion that serves as an inlet to which the molten metal M is supplied. ), The molten metal M flows down and the gas G is supplied to each of the inlets to the runner 10h. That is, in this embodiment, the molten metal flow path 10c is comprised by the gate part 10f and the runner part 10h, and the molten metal M and gas G supplied through the molten metal part 10f are in the molten metal flow path 10c toward the product cavity 10b. Will flow. The supply hole 10g of the present embodiment for supplying the coolant C is a bottomed hole as described above, and the mold (raw sand mold) is directed from the upper side to the lower side of the upper mold 10m so that the bottom surface is formed. Are directly drilled. In other words, the supply hole 10g, which is a bottomed hole with a raw sand mold exposed on the inner peripheral surface and the bottom surface, has an upper end (one end) opened on the top surface of the mold 10 and a bottom surface (the other end) on the bottom surface. It arrange | positions so that the road 10c may be faced.

  In FIG. 1, reference numeral 11 has a gas supply nozzle 11 b whose tip is connected to a gate portion 10 f (introduction rod portion 10 e in FIG. 1), and gas is supplied from the gas discharge portion 11 a to the molten metal flow path 10 c through the nozzle 11 b. This is a gas discharge device for supplying G. Reference numeral 12 has a nozzle 12b for supplying a coolant inserted into the supply hole 10g formed above the molten metal flow path 10c as described above, and supplies a metal medium C as a coolant to the supply unit. It is a coolant supply apparatus supplied from 12a through the nozzle 12b. As shown in FIG. 1, in this embodiment, the nozzle 12b of the coolant supply device 12 is inserted into the supply hole 10g previously formed in the mold 10, but the supply hole 10g is formed in the mold 10 in advance. Instead, the supply hole 10g may be formed by inserting the nozzle 12b into the mold 10 and pushing it. Further, the timing of inserting the nozzle 12b into the supply hole 10g is not limited as long as it is before the start timing of the cooling process.

  A casting method of this embodiment using the mold 10 having the above-described configuration will be described. First, as shown in FIG. 1A, which is a molten metal supply step, a molten metal M that is sufficient to fill at least part of the product cavity 10b and the molten metal flow path 10c in the mold cavity 10a from the pouring ladle 13 is provided. 10f is supplied into the molten metal flow path 10c.

  Next, as shown in FIG. 1B, which is a molten metal filling step, the gas G is sent from the gate portion 10f to push the molten metal M in the molten metal flow path 10c, and the product cavity 10b is filled with the molten metal M. . Specifically, the nozzle 11b of the gas discharge device 11 that discharges the gas G is connected to the gate portion 10f (introduction rod portion 10e in FIG. 1), and the molten metal M supplied into the molten metal flow path 10c in the molten metal supply step. Before the solidification of the gas starts, the gas G is sent from the nozzle 11b to the mold cavity 10a. By this operation, the rear end of the molten metal M that is in contact with the gas G receives the wind pressure from the gas G and is pushed toward the product cavity 10b to flow in the molten metal flow path 10c, so that the molten metal M enters the product cavity 10b. Filled. Further, in the molten metal supply process, since the molten metal M that fills a part of the molten metal flow path 10c is supplied, a part of the molten metal flow path 10c is also filled with the molten metal M.

  The gas G used in the molten metal filling process may be air from the viewpoint of cost, and from the aspect of preventing oxidation of the molten metal, for example, argon, nitrogen or carbon dioxide may be used. Good. Further, the gas G may be sent by a fan, a blower or the like, but it is preferable to use a compressed gas by a compressor or the like because the molten metal M can be pushed more uniformly in a pressurized state. Furthermore, in order to further promote the solidification of the molten metal M existing in the molten metal flow path 10c, moisture, preferably mist-like moisture, may be added to the gas G.

  Next, as shown in FIG. 1C, which is a cooling process, a plurality of metal spheres C, which are coolants, are discharged from the nozzles 12b inserted into the supply holes 10g, and the molten metal existing in the molten metal flow path 10c. The metal sphere C is supplied through the supply hole 10g so as to touch at least a part M1 of M. Thereby, a part M1 of the molten metal M existing in the molten metal flow path 10c is cooled and solidified preferentially over the molten metal M filled in the product cavity 10b. As a result, the molten metal M filled in the product cavity 10b in the molten metal filling step is reliably prevented from flowing back toward the gate portion 10f by the part M1 of the molten metal M that has solidified into a plug shape. It becomes possible to maintain the filling state in the product cavity 10b.

DESCRIPTION OF SYMBOLS 10 Breathable mold 10a Mold cavity 10b Product cavity 10c Molten flow path 10d Pouring cup part 10e Introducing gutter part 10f Pouring part 10g Supply hole 10h Runway part 10i Part of breathable mold 10j Upper frame 10k Lower frame 10L Surface plate 10m Upper Type 10n Lower type 11 Gas discharge device 11a Gas discharge unit 11b Gas supply nozzle 12 Coolant supply device 12a Supply unit 12b Nozzle 13 Pouring ladle C Coolant G Gas M Metal melt M1 Metal melt existing in the melt flow path Part of M2 Rear end surface of molten metal present in molten metal flow path

Claims (4)

  A molten metal supplying process for supplying at least a part of the product cavity and a part of the molten metal flow path from the mold part to the molten metal flow path, and then supplying gas from the molten metal part to the molten metal. A molten metal filling process for filling the product cavity with the molten metal by pushing the molten metal in the flow path, and at least a part of the molten metal present in the molten metal flow path is more than the molten metal filled in the product cavity. And a cooling step of preferentially cooling and solidifying or semi-solidifying the casting article, wherein the cooling step touches at least a part of the molten metal present in the molten metal flow path. A method for producing a cast article, comprising supplying a coolant having fluidity through a supply hole formed at a position different from the gate.   The method for producing a cast article according to claim 1, wherein the cooling material is a metal ball, a metal particle, a metal piece, or another metal medium.   The supply hole is a bottomed hole, and a part of the breathable mold is interposed between the bottom surface of the supply hole and the molten metal flow path. The manufacturing method of the casting article of Claim 1 or Claim 2 which pumps the said cooling material so that a part may be broken.   4. The cast article according to claim 1, wherein, in the cooling step, the cooling material is supplied through a supply hole provided on the product cavity side with respect to a rear end surface of the molten metal existing in the molten metal flow path. Production method.

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