JPH0399747A - Method for casting dual type exhaust manifold - Google Patents

Abstract

PURPOSE:To lighten a casting by arranging a sprue and runner to a lost foam pattern to form an embedding body, embedding this into non-combustible packing material charged in a flask, pouring molten metal, executing thermal decomposition of the lost foam pattern and replacing this with the molten metal. CONSTITUTION:A first and second branched tubes 4, 8 formed as bending with material lost by heating, are set at front and back sides and branched passages 2, 3 and branched pipe conduits 6, 7 in both branched tubes 4, 8, respectively are connected with flange 11 having the same material. As the same way, the passage and pipe conduit are connected with a second flange 12 to form the lost foam pattern 13. By arranging the sprue 16 and runner to this pattern 13, the embedding body 17 is formed and embedded into the non-combustible packing material 20 charged in the flask 19, and molten metal 22 is poured from the sprue 16. The molten metal reaches the pattern 13 and then, the thermal decomposition is executed to this and the molten metal is entered into the space generated in there and cast. As the shifting between a master mold and core is not developed, allowable space to the shifting of core can be neglected and the casting weight can be lightened by the corresponding weight. Further, as removal work of casting flash is unnecessary, the labor saving is attained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for casting a dual type exhaust manifold used in internal combustion engines and the like.

[Prior Art] Conventionally, so-called dual type exhaust manifolds as shown in FIGS. 6 and 712I have been widely used. In the figure, a is a first flange, which is installed on a cylinder of an engine (not shown), and b is a second flange, which is connected to an air supply device (not shown). C indicates piping. Further, the entire structure is formed into a three-dimensionally complex shape as shown in the figure.

When such a dual type exhaust eyebrow hold is cast, the mold is formed approximately as shown in FIG. 8. That is, in the same figure, d is the upper mold of the main mold, e
is the lower mold, and f is the core. Also, g and h are piping cores, i and j are the first and fourth boat cores, respectively, and k
, Meng indicate the second and third boat cores, respectively. To give an example of the mutual positional relationship of these members, looking at the cross section of the mold corresponding to the A-A cross section of the manifold shown in FIG. 9, it is formed as shown in FIG. 10. There is. In the figure, m indicates a space for allowing displacement of the core, n indicates a draft space, and p indicates a part where paris occurs.

Using such a mold, molten metal is injected and cast.

[Problems to be Solved by the Invention] However, the above-mentioned conventional casting method for the dual type Exith 1 to manifold has the following drawbacks.

The problem is that when the piping cores g, 1] are first set in the main molds d, e, misalignment occurs between the main molds d, e and the piping cores g, 1]. It is almost impossible to eliminate this misalignment at all using conventional methods.

Therefore, as shown in FIG. 10, the wall thickness is set to a space m that allows for the displacement of the core, which increases the weight of the casting. Also, although not shown in the drawings, when releasing the model from the mold during mold forming, it is necessary to have a large draft angle to prevent sand from falling and corner damage, etc., as shown in Figure 10. As such, a draft space n is created in the main mold, which increases the amount of waste material and increases the weight accordingly.

In addition, as shown in Fig. 10, the mating surface for the mold separation of the main mold,
Casting flash is formed where the main mold and core fit together, but this obstruction requires troublesome removal work, and furthermore, it is usually difficult to completely remove this flash, and only residual flash is likely to occur. , the weight increases accordingly. In addition, those using the above conventional method,
As mentioned above, the thermal deformation force increases during running due to the waste material being removed, so it is necessary to ensure its strength.
Furthermore, the weight increases.

This invention was made in order to solve the drawbacks of the conventional method as described in 1.The purpose of this invention is to make the vehicle lighter and lighter than the conventional method, and to eliminate the troublesome work of deburring. An object of the present invention is to provide a method for casting an unnecessary dual-type exhaust eyebrow hold.

[Means for Solving the Problems] This invention, which achieves the above object, is described as follows: One passage formed by a vanishing material that generates gas and disappears when heated is branched into two branch passages, and in a virtual plane including the ball passage, a first branch pipe bent in a direction intersecting the virtual plane and one pipe line formed by the disappearing material are branched into two branch pipe lines, and In a virtual plane including the three pipes, a second branch pipe is formed bent in a direction intersecting the virtual plane, and the branch width of the second branch pipe is formed to be smaller than the branch width of the first branch pipe. , the two branch pipes are arranged in front and behind each other with their bending surfaces in the same direction, the two branch passages and the two branch pipes are connected via a first flange formed of the vanishing material, and The passage and the pipe are connected via a second flange formed by the fugitive material H to form a fugitive model, a plan is connected to the model to form a buried body, and the buried body is coated. A mold layer was formed, the embedded body was embedded in a nonflammable filler contained in a flask, and melted using the above method. This is a method for casting a dual-type exhaust eyebrow fold, which is characterized in that metal is injected, the fugitive model is thermally decomposed by the heat of the molten metal, and casting is performed by replacing it with the molten metal.

[Embodiment] In FIG. 1, 1 is a passage, and a first branch pipe 4 is formed by branching the passage 1 into two branch passages 2.3. The material wart 1 of the first branch pipe 4 is, for example, foamed polystyrene, but it may be made of any other material that generates gas and thermally decomposes when heated. Although not shown in the drawings, the first branch pipe 4 is generally divided into two parts in the vertical direction and bonded together with an adhesive.

Next, 5 is a pipe, and the pipe 5 is divided into two branch pipes 6 and 7.
A second branch pipe 8 is formed by branching into. Note that the second branch pipe 8 is also formed of the same material as the first branch pipe 4, and is formed by the same method.

The branch width 9 of the second branch pipe 8 is the same as that of the first branch pipe 4.
The branch width 4.8 is smaller than the branch width 10 of , and both 4.8 and 4.8 are bent in a direction intersecting an imaginary plane containing three passages or three ducts, respectively, as shown in the figure. Next, both 4.8 are the second
As shown in the figure, the branch passage 2
．． 3 and branch line 6.7 are each connected via a substantially straight first flange 11. Furthermore, the passageway] and the pipe line 5 are also connected via the second flange 12. Note that both flanges 11.12 are also formed of foamed polystyrene similarly to the first and second side branch pipes 4.8. Furthermore, 1 note 1
The parts 11.8, 11.12 are each bonded with adhesive. In this way, a fugitive model 13 is formed.

Next, the evanescent model 13 has a sprue 14 as shown in FIG.
Plan 16 such as runner 15 will be connected. In this case, the runner 15 is made of the same material as the disappearing model 13,
The sprue 14 was formed of sand and synthetic resin. In this way, buried installation 4C17 was formed.

Next, although not shown, a coating layer is formed on the outer surface of the buried body 17. The coating layer is made by coating and drying fine particles of various minerals such as silica dissolved in a binder such as blackstrap molasses.

In this case, it is not necessary to form a coating layer on the sprue 14.

Further, when creating the evanescent model 13, the relative positional relationship of the first branch pipe 4 and the second branch pipe 8 does not require complicated consideration.

This is because the branch passages 2.3 and branch pipe lines 6.7 are automatically inserted into the holes formed in the first flange 11. Therefore, the first flange 11 is 11Zrv.
1. The second flange 12 also serves as a JJA control member, and the second flange 12 also serves as a position control member.

Therefore, the work of creating the evanescent model 13 is extremely easy.

Next, the evanescent model 13 may also be formed as shown in FIGS. 3U and 4.

That is, in FIG. 3, the first branch pipe 4 is integrally formed with a part 11a of the first flange 11 and a part 12a of the second flange 12 during its manufacture.

Also, as shown in the figure, the second branch pipe 8 also has a first flange 11.
A part 11b of the second flange 1 is integrally formed, and the second flange 1
Part 12b of 2 is integrally formed.

The above-mentioned two 4.8 are formed in combination as shown in FIG. 4, and the first and second side flanges 11.12 are respectively bonded 18 with an adhesive.

In this way, a fugitive model 13 is formed by the first branch pipe 4, the second branch pipe 8, the first flange 11, and the second flange 12. Then, the method 16 is provided on the model 13 as described above, the buried body 17 is formed, and a coating layer is formed on the buried body 17.

As described above, two embodiments have been described regarding the method of creating the buried body 17 having a coating layer, and the buried body 17 formed in this manner can be manufactured in a number of ways by partially changing the manufacturing order and manufacturing method. Possible methods are:

However, all of them are included in this invention.

Next, the buried body 1 having the coating layer formed in this way
7 is buried in a filler 20 such as sand in a flask 19 as shown in FIG.

Then, as shown in the figure, molten metal 22 is injected from the furnace 21 through the sprue 14, and the fugitive model 13 is gasified and disappeared by the heat of the metal 22, and the molten metal 22 is in the space created there. Infiltration and casting takes place. Note that the runner 15 also disappears at this time. The generated gas is treated by various known methods. To give an example,
In FIG. 5, reference numeral 23 denotes a burner partially embedded in the filling material 20, and a large number of small holes or slits 24 are formed in the side wall 24 of the burner 23.
An ignition device 27 is provided above the upper end 26 .

The gas generated by the thermal decomposition passes through the gap between the fillers 20 and enters the burner 23 through the small holes 25 of the burner 23,
The fuel then rises to reach the upper end 26, where it is ignited by the ignition device 27 and combusted. Due to this combustion, the inside of the burner 23 becomes a negative pressure, and the gas is vacuumed.

Casting is thus performed. Note that 28 indicates a roll, and 29 indicates a shaft support.6 [Effects of the Invention] This invention is constructed as described above, and is bent and formed as described above using a material that thermally decomposes when heated, generates gas, and disappears. The first branch pipe 4 and the second branch pipe 8 are arranged in front and behind each other, and each branch passage 2.3 of both branch pipes 4.8
and the branch pipe 6.7 are connected via a first flange 11 made of the same material, and the passage 1 and the pipe 5 of both branch pipes 4.8 are connected via a second flange 12 made of the same material. , vanishing model 13
A method 16 is provided on the fugitive model 13 to form a buried body 17, and a coating layer is applied to the buried wood 17. By embedding it in the filler 20, injecting the molten metal 22 from the method 16, allowing it to reach the fugitive model 13 and thermally decomposing it, and infiltrating the space created there and casting, the Uf, Since there is no risk of misalignment between the main molds d and e and the cores g and h as mentioned in the next example, the space allowed for core misalignment can be eliminated, and the weight can be reduced accordingly. In addition, since the fugitive model j3 can generally be made of a flexible material such as foamed polyurethane, it can be easily removed from the mold during production, and therefore the draft angle of the mold can be made extremely small, or it can be eliminated. , the casting can be weighed by that amount.

Also, the burr removal ft work can be omitted.

Also, it is possible to eliminate the increase in weight due to unaccumulated flash. In addition, since there is no risk of spoilage as mentioned above, there is little thermal deformation during running, and therefore, it is possible to eliminate the need to increase the number of layers to increase the strength.

[Brief explanation of drawings]

1 and 2 show an embodiment of the present invention, FIG. 1 is an exploded perspective view of a fugitive model used in the method for casting a dual type exhaust manifold, FIG. 2 is a perspective view of the same fugitive model, and FIG. Figures 3 and 4 show examples of the pond according to the present invention, with Figure 3 corresponding to Figure 1, Figure 4 corresponding to Figure 2, and Figure 5 showing the vanishing model. 6 is a front view of a conventional dual type exhaust manifold, FIG. 7 is a side view of the same, and FIG. 8 is a conventional dual type exhaust manifold.
An exploded perspective view of the mold used for casting the manifold,
9 is a perspective view of the part of the apparatus shown in FIG. 6, and FIG. 10 is a sectional view of the mold shown in FIG. 8, corresponding to the plane AA in FIG. 9. 1... Passage 2... Branch passage 3... Branch passage 4... First branch pipe 5... Pipe line 6... Branch pipe line 7... Branch pipe line 8... Second Branch pipe line 9... Branch width 10... Branch width 11... First flange 12... Second flange 13... Disappearance model 16... Plan 17... Buried tree 19... Flask 20... Filler 22... Molten metal

Claims (1)

[Claims] One passage formed by a vanishing material that generates gas and disappears when heated is branched into two branch passages, and in an imaginary plane containing the three passages, the first passage is bent in a direction intersecting the imaginary plane. One branch pipe and one pipe line formed by the vanishing material are branched into two branch pipe lines, and in a virtual plane including the three pipe lines, a first pipe is bent in a direction intersecting the virtual plane. A two-branch pipe is formed, the branch width of the second branch pipe is formed to be smaller than the branch width of the first branch pipe, and the two branch pipes are arranged in front and behind each other with their curved surfaces in the same direction. connecting the passageway and both branch conduits via a first flange formed by the dissipating material; and connecting the passageway and the conduit via a second flange formed by the dissipating material; A fugitive model is formed, a plan is connected to the model to form a buried body, a coating layer is formed on the buried body, and the buried body is buried in a nonflammable filler contained in a flask. , a method for casting a dual type exhaust manifold, characterized in that molten metal is injected according to the above method, the heat of the molten metal thermally decomposes the fugitive model, and casting is performed by replacing the molten metal with the molten metal. .