JPS60174246A - Insert casting method of pipe or the like - Google Patents

Abstract

PURPOSE:To prevent effectively generation of a blow and to obtain a casting having good quality by inscribing many fine grooves for releasing gas in the region from the point of a pipe, etc. where generation of the blow is anticipated to the end part of an insert casting material, supporting said material in a casting mold and pouring a molten metal therein. CONSTITUTION:Fine grooves 7 for gas releasing parallel with the axial center of the pipe 2 is inscribed at every other suitable intervals in the circumferential direction on the outside circumferential surface of an aluminum pipe 2 to be used in the case of producing, for example, an intake manihold. The end part 2b of such pipe 2 that has the grooves 7 and is held bent to a prescribed shape is tightly fitted for a prescribed length into the recesses 10a, 10b formed between vertically splittable width regulating parts 9a and 9b of a casting mold by which the pipe is supported in the casting mold. A molten metal is poured into the mold in this state and a manihold body 3 is cast.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for casting a casting integrally containing a casting material such as a pipe.

Recently, in the automobile industry, various improvements have been made in order to meet exhaust gas regulation values. For example, one example is an exhaust gas recirculation system that circulates part of the exhaust gas into the engine cylinder. It is necessary to add a circulation pipe for exhaust gas, and attempts have been made to integrate this circulation pipe into the manifold main body to make it more compact. As a method for integrally providing the exhaust gas circulation pipe inside the manifold body, the applicant of the present invention has already proposed a method in which an aluminum pipe is bent into a predetermined shape and is integrally cast when the manifold body is cast. Proposed.

Figure 1 shows an intake manifold 1 with a built-in exhaust gas circulation pipe manufactured by this method, and an aluminum pipe 2 pre-bent into a predetermined shape to form an output gas circulation pipe. is integrally cast in a predetermined position inside the intake manifold body made of aluminum alloy casting.

This aluminum pipe 2 is subjected to necessary pretreatment such as heat-resistant coating in order to increase the pipe's resistance to molten metal and prevent so-called melting damage, and even if it is a thin-walled pipe, it can be integrated into one piece without any problems. I was able to cast it, but
In order to further improve quality, it has been found that it is necessary to take measures to eliminate casting defects, which are generally referred to as nuisances.

That is, when the aluminum pipe 2 is supported at a predetermined position in the mold for casting the manifold body 6 as shown in FIG. 2, the upper side 4 of the mainly horizontal portion 2a of the vibrator 2 It has been found that a cavity called a so-called "chirai" is generated on the lower side 5. In particular, as shown in FIG. 3, when a constricted part 6 for finishing the inner diameter to a predetermined size is formed in the horizontal part 2a of the aluminum pipe 2, upper and lower sides 4 adjacent to the inside of the constricted part 6 A large "disgust" was observed on .5.

The cause of such "disgust" is that impurities such as oil adhering to the surface of the aluminum pipe 2 during the manufacture of the aluminum pipe 2 do not dissipate out of the molten metal when they come into contact with the molten metal. It is thought that the gas remains on the upper side 4 and lower side 5 of the horizontal pipe portion 2a and becomes a gas pocket. Since the presence of such "disgust" is an obvious casting defect and reduces quality, the occurrence of "disgust" must be completely prevented.

The present invention provides a casting method that can effectively prevent the occurrence of "1-Kai" when casting pipes etc. in one piece as described above, and that can easily obtain high-quality cast products. There are things to do.

According to the casting method of the present invention, a large number of narrow grooves for gas release are formed in the outer circumferential surface of a cast walnut material such as a pipe, at least in a region from a place where chili is expected to occur to the end of the spun walnut material. The cast walnut material is supported in a mold and poured into the mold.

Embodiments of the present invention will be described below based on the attached illustrative drawings.]
Fig. 2L4 shows an aluminum pipe 2 used when manufacturing the intake manifold 1 by the method of the present invention, and the outer circumferential surface of the vibe 2 has a groove extending parallel to the axis of the pipe over its entire length. Gas release narrow grooves 7 are formed at appropriate intervals in the circumferential direction. Instead of the narrow grooves 7, mesh-like narrow grooves 8 as shown in FIG. 5 may be cut along the entire circumference and length of the pipe 2. The mesh-like narrow grooves 8 are shown as twill-like grooves that are inclined at an appropriate angle with respect to the axis of the pipe 2, but a combination of longitudinal grooves parallel to the pipe axis and circumferential grooves is shown. It may also consist of Further, spiral grooves and the like are also possible.

The pipe 2 having the narrow groove 7 or 8 for gas release as described above is bent into a predetermined shape and supported at a predetermined position in a mold as shown in FIG. The end portion 2b of the pipe 2 is tightly fitted for a predetermined length into four portions 10a and 10b formed between the upper and lower divisible +13-square portions 9a and 9b of the mold, thereby being supported by the mold. With the pipe 2 supported at a predetermined position in the mold, the manifold body filter is cast by pouring metal, and the pipe end 2b protrudes from the end face of the manifold body 6 which is taken out by disassembling the mold. By performing necessary post-processing such as cutting, the intake manifold 1 as shown in FIG. 1 is completed.

According to the method of the present invention, which can be implemented as described above, the gas that tends to stay at the locations where "disgust" is expected to occur as shown in FIG. It moves toward the pipe end 2b through the inside of the linear narrow groove 7 or the narrow groove 8, and then moves from the inside of the recess 1'Oa, 10b of the i+circular groove 9a9b to both the upper and lower middle grooves 9a, ? It can flow out of the mold, that is, out of the molten metal, through the seam 11 between b.

Various cross-sectional shapes can be considered for the narrow grooves 7 and 8, but it is desirable that the cross-sectional shape is such that a gas venting passage can be secured at the bottom of the groove at least until the time period corresponding to pouring has elapsed. From this point, the arc-shaped bottom 1 shown in FIG.
2 or a narrow groove with a flat bottom 16 as shown in Fig. 7, it is said that it is easy for the cast /g hot water to instantly fill up to the bottom of the narrow groove. It is preferable to use a gutter with a cross-sectional shape that is not too bright and has a V-shaped pointed bottom 14 as shown in FIG. Of course, if the angle θ between both sides of the V-shaped pointed bottom portion 14 is too large, it is possible that the gas venting passage cannot be maintained at 6° as described above, and conversely, the angle θ is too small. When this happens, the molten metal becomes a knife-shaped groove in cross section and no molten metal flows into the groove, reducing the adhesion between the pipe 2 and the manifold body 6. Therefore, the angle θ must be selected within an appropriate range. However, the embodiment shown in FIG. 8 shows a narrow groove with an angle θ of 90°, which was adopted in the experiment and was confirmed to be able to achieve the intended purpose.

Furthermore, if the individual cross-sectional areas of the narrow grooves 7 and 8 are too large, the cast molten metal may pass through the narrow grooves 7 and 8 and reach the end portion 2 of the vibrator.
There is a possibility that it may flow into the pipe 2 from b or flow out of the mold. On the other hand, if the cross-sectional area is too small or the pitch of the narrow grooves 7 and 8 is too rough, a sufficient degassing effect cannot be expected and the occurrence of "disgust" cannot be completely suppressed. The individual cross-sectional areas and pitches of 7 and 8 must also be set with sufficient consideration.

The applicant of the present invention has tried various experiments in view of the above points, and has developed an aluminum alloy casting intake manifold 1 with a wall thickness of 1 fin and an outer diameter of approximately 161 mm, which incorporates the exhaust gas circulation pipe described above. The results obtained when manufacturing aluminum pipes by integrally casting them are listed below.

(1) Although the narrow grooves can be formed by a general one-column processing method, the vertical line-shaped narrow grooves 7 can be formed at the same time as extrusion molding of the pipe, so manufacturing is easy.

(2) Thin vertical line? ? Xi7 and mesh-like (twill-like) thin i
When compared with A in terms of degassing effect, the fine grooves 8 were the best, and no "disgust" was observed due to the complete degassing effect. In the case of the vertical linear narrow groove 7, some gas accumulation was observed on the −1 side 5 of the horizontal pipe portion 2a in FIG. 2, but there was no harmful gas accumulation.

(3) As shown in FIG. 8, when providing a vertical linear groove 7 with a v-shaped cross section and an angle θ of 90° between both side surfaces, the pitch P is 1".
I tested it by changing m% 1.5m+n and 2 tuna,
At P='2RI11, degassing took slightly less than 1 minute,
Outgassing was good at P=1 in and 1.5 order. Furthermore, the depth D is 0.20 mm, 0.25
I tested three types of cheeks: m+n and 0.35 m++.
At a depth of 0.2511 m or more, the angle θ is constant at 90°, so the cross-sectional area becomes too large, and there is a tendency for molten metal to leak from the pipe end, D = 0.2
0 Ryu level was appropriate. Further, if D-0, 20s+m was present, even when the constricted portion 6 was processed as shown in FIG. 3, the narrow groove 7 would not disappear in the constricted portion 6.

(4) As explained above, the V-shaped cross-sectional shape of the bottom of the narrow groove is optimal, and an arc-shaped or flat bottom does not provide a sufficient degassing effect.

Taking all the above into account, under the above test conditions,
From the point of view of degassing effect, the optimal narrow grooves are mesh-like (twill-like), with a depth of about 0.20 mm, and the finer the mesh size, the better, but in terms of manufacturing cost. Taking this into consideration, it was found that a narrow vertical groove with a pinch of about 1.5 fins and a depth of about 0.20i+a is suitable.

The casting method of the present invention can be carried out as described above, and is an extremely advantageous manufacturing method when manufacturing an intake manifold with a built-in exhaust gas circulation pipe as described above. It was possible to effectively prevent the occurrence of "disgust" on the circumferential surface of the cast pipe, and it became possible to easily obtain high-quality cast products free of casting defects. It has also been found that by omitting the degreasing treatment, which was essential as a pretreatment for the pipe to be cast, and simply performing a cleaning treatment, a high-quality product without any unpleasantness can be produced.

In the example, the narrow grooves for gas escape were formed over the entire length of the pipe, but at least from the places where Kirai 1 is expected to occur (that is, in the example of FIG. 2, the upper and lower sides 4 and 5 of the horizontal part 2a of the pipe). The intended purpose can be achieved by providing the narrow groove in the region reaching the vibrator end 2b. Furthermore, the method of the present invention is not limited to the manufacturing method of the intake manifold as shown in the embodiments (but can also be applied to the manufacturing of any other cast products. The casting material to be cast is not limited to pipes either.

[Brief explanation of drawings]

Fig. 1 is a side view of an intake manifold that can be manufactured by the method of the present invention, Fig. 2 is a vertical cross-sectional side view illustrating locations where "disgust" is expected to occur when casting the same manifold L-, and Fig. 3 is a side view of the main part of the pipe that adjusts the throttle part,
Fig. 4 is a side view of the main part of the pipe used in the method of the present invention, Fig. 5 is an explanatory diagram of the mesh-like narrow grooves, and Figs. 6 and 7 are longitudinal sections showing the narrow grooves with different cross-sectional shapes. FIG. 8 is a longitudinal sectional front view of a main part of a pipe according to an embodiment of the present invention. 1... Intake manifold, 2... Aluminum pipe, 6... Aluminum alloy casting manifold body, 4.5... Upper and lower sides of pipe horizontal portion 2a (locations where "disgust" is expected to occur) , 6... aperture section, 7...
・Vertical linear grooves, 8...Mesh-like narrow grooves, 9a, 9b・
... 111 round portions of the mold, 10a, 10b... recessed portions that support the pipe end 2b, 11... seams, 12...
Arc-shaped bottom, 16... flat bottom, 14... V-shaped pointed bottom. Patent Applicant: Nakamura Konku Kogyo Co., Ltd. Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Procedures Amendments Documents and Illusions June 20, 1981 Director-General of the Patent Office Kazuo Wakasugi (Patent Indication of Office Examiner Cases 1981 Patent Application No. 3121, Title of Invention Relationship with each case amending the casting method for pipes, etc. Person Address (Residence) Name Nakamura Metal Industry Co., Ltd. Details of the amendment are as shown in the attached sheet.

Claims (1)

[Claims] A large number of narrow grooves for gas release are carved in the outer circumferential surface of the cast material such as pipes, at least in the area from the area where the occurrence of oxidation is expected to the end of the cast material. A method for casting walnuts such as pipes, which is characterized by pouring metal while supporting it in a mold.