JPS623863A - Casting method for turbine housing by insert casting of heat resistant ring - Google Patents

Abstract

PURPOSE:To reduce the cost of production by providing notches to a heat resistant ring, subjecting the ring to degreasing and surface roughening treatments, grasping the ring between the mating surfaces of split cores and executing vertical type casting. CONSTITUTION:One or plural notches are formed to the outside circumferential surface 3a of the part to be inserted by casting into a base material 1 for the heat resistant ring 3. These notches are mechanically meshed with the base material 1. The ring 3 is then cleaned by an org. solvent as a pretreatment and is further subjected to the surface roughening treatment. The ring 3 is set to the prescribed position of the mating surfaces 7 of the split cores 5 and the core is assembled by fitting a projecting surface 9 to a recessed surface 8. Vertical type casting is executed by pouring a molten metal through the sprue while the assembled core 6 is held to a master mold via a core print. The dimensional accuracy of the insert casting is improved by the above- mentioned method and the reduced cost of production is resulted from the saving of the base material cost.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a tip portion formed at an acute angle of a scroll internal partition portion of a variable amount turbine housing.
Regarding the method of casting a variable capacity turbine housing by casting a heat-resistant ring with excellent wear resistance, more specifically, the method of casting a variable capacity turbine housing by casting a heat-resistant ring with excellent wear resistance.
This invention relates to a casting method that stabilizes the shape, pretreatment method, and dimensions of a heat-resistant ring.

Conventional technology and problems Conventionally, in the manufacture of variable displacement turbine housings, it has been necessary to develop a housing with particularly excellent heat resistance and wear resistance, which can withstand the sharply angled tip of the internal scroll partition, which is exposed to the harshest conditions. Since the base material was manufactured from an expensive material, there was a problem in that it was very expensive. To solve this problem, the base material is manufactured from a material with a certain degree of heat resistance and wear resistance, and only the tip of the partition part, which is exposed to harsh conditions, is
Combination turbine housings manufactured from materials with particularly excellent heat resistance and wear resistance have been proposed, but casting these dissimilar materials in particular during casting poses problems in adhesion with the base material and problems during casting. Due to the pressure of the molten metal, the relative position of the base metal and the part to be cast will shift due to lifting or movement of the part to be cast, resulting in dimensional variations, making the dimensions unstable and reducing the normal dimensional accuracy. It has not yet been put into practical use due to the problem that it cannot be obtained.

Means for Solving the Problems The present invention has been made by focusing on these conventional problems, and includes pre-treatment (degreasing, roughening treatment) of casting materials, improvement of adhesion by shape, and The purpose of this invention is to solve the above-mentioned problems by sandwiching the casting material between the split cores and stabilizing the dimensions through a vertical casting method.

The present invention provides a casting method for stabilizing the shape and pretreatment of the heat-resistant ring 3 and the dimensions of the heat-resistant ring 3 to be cast, in order to improve the adhesion between the base material 1 and the heat-resistant ring 3 to be cast. Consisting of

For the purpose of improving adhesion, the outer circumferential surface 3a of the part of the heat-resistant ring 3 that is cast into the base material 1 is
One or more notches 4 are formed in the base material 1 to mechanically engage with the base material 1. Next, as a pretreatment for the heat-resistant ring 3, moisture, oil, etc. that are harmful to adhesion are washed away using an organic solvent, and finally, shot or Using a grid, blasting is performed to roughen the surface. The heat-resistant ring 3, which has been subjected to surface roughening treatment, is immediately set in a mold and casting is performed. The time from blasting to set casting should be as short as possible, at most no more than 6 hours, to minimize the occurrence of rust due to activation of the surface after blasting.

The molds in which the heat-resistant ring 3 is set and cast are shown in Figures 4 and 6.
As shown in the figure, when the vertical casting method is used, the heat-resistant ring 3 floats up and moves toward the outlet or the center housing when molten metal is poured, which is significantly less than in the case of flat casting.

Furthermore, the heat-resistant ring 3 is held between mating surfaces 7 of several split cores forming the inside of the scroll. As shown in FIG. 3, the two split cores 5 and 6 are fitted snugly into the recess 8 provided on the core 5 and the protrusion 9 provided on the core 6. Since the assembled cores are firmly held by the cores 10.degree. 11 and 12.13 provided on the main mold, the positional dimensions of the cores relative to the main mold are maintained correctly. Therefore, the mating surface 7 of the cores 5 and 6
Since the heat-resistant ring 3 is firmly clamped, it has good stability and good relative dimensional accuracy with respect to the base material, making it possible to cast the ring at a predetermined position.

Example Scroll partition part 2 is made of martensitic stainless steel (S
The heat-resistant ring 3 made of O3410) was used, the main body base material 1 was a spheroidal graphite cast iron material (FCD45), the split cores 5 and 6 were hot box molded (shell type), and the main mold was an organic self-hardening mold. As shown in FIGS. 1 and 2, the shape of the heat-resistant ring 3 is as follows: In order to improve adhesion, eight notches 4 of appropriate shape and size are provided on the outer peripheral surface 3a that is cast into the base material. As a pretreatment, the sample was first washed with trichloroethane, and then blasted with an alumina grid having a particle size of 800-1000 microns for 1 minute. The surface roughness of the heat-resistant ring 3 was approximately 60S after blasting.

After blasting, it took about 4 hours to set the heat-resistant ring 3 in the mold, and about 5 hours to cast.

The casting method was a vertical casting method as shown in Figures 4 and 5. Set the heat-resistant ring 3 at a predetermined position on the mating surface 7 of the split core 5, and insert the convex 9 of the split core 6 into the concave 8 of the split core 5 using the mating surface 7. Fit snugly and assemble. The assembled cores are main mold cores 10, 11 and 12.
13, it is firmly held in the main mold. Molten metal is poured into the mold with the core set through the sprue 14. The poured molten metal is filled into the turbine housing body 1 and the top riser 17 from below through the runner 15 and a plurality of weirs 16 that connect the runner 15 and the turbine housing body 1.

The investigation results of the turbine housing manufactured by the above-mentioned casting method of enclosing the heat-resistant ring 3 according to the present invention are as follows.
Both the dimensional accuracy and adhesion of the heat-resistant ring 3 were good.

(1) Dimensional Accuracy The dimensional position of the heat-resistant ring 3 moved within 0.1t+no at the maximum from the predetermined regular dimensional position, and was dimensionally stable and had no problems at all.

(n) The following test was conducted regarding adhesion.

(1) Fracture surface test As shown by the dashed line in FIG. 7, the turbine housing body 1 was cut and a color check test was performed on the cross section of the heat-resistant ring 3 cast into the base material. If there were any areas with poor adhesion, the red penetrant penetrated into those areas and a red reaction was observed, so adhesion was determined based on the presence or absence of such areas. As a result, no red reaction was observed and it was confirmed that the adhesion was good.

(2) Thermal Fatigue Test As shown in FIG. 6, two holes 18 and 19 were made on the surface of the turbine housing main body by electrical discharge machining, and the temperature of the heat-resistant ring in the holes 18 was measured.

A thermocouple 20 is inserted into each of the holes 19 to measure the temperature on the surface of the main body, and the combustion gas flame is emitted from the gas inlet of the turbine housing main body, and the emitted gas flame passes through the internal scroll and is discharged from the exit side. 5 heating/cooling cycles of heating for about 3 minutes and then forced air cooling for about 3 minutes.
As a result of repeating this process 00 times, there was a temperature difference of approximately 100°C between the heat-resistant ring part and the surface temperature of the turbine housing body, and this large temperature difference caused a high load to be applied to the ring 3 and the base material 1 due to the imbalance of thermal stress. Adhesion was good even though it was subjected to severe thermal stress. In variable capacity turbine housings, the main body base material is made of a relatively inexpensive material that has a certain degree of heat resistance and wear resistance, and is Only the tip of the partition part, which is exposed to harsh conditions, is made of an expensive material with particularly good heat resistance and wear resistance, and can be integrally cast with good adhesion and dimensional accuracy to the main body base material. As a result, the material cost of the main body base material is greatly reduced,
The effect of reducing the manufacturing cost of the variable capacity turbine housing is significant.

[Brief explanation of the drawing]

Figure 1: Front view of the heat-resistant ring Figure 2: Cross-sectional view taken along line A-A in Figure 1 Figure 3: Cross-sectional view of the main parts of the mold showing how the heat-resistant ring is clamped Figure 4: Explanation of the vertical casting method Side view Figure 5: Front view explaining the vertical pouring method Figure 6: Schematic diagram showing the temperature measurement method for fatigue testing Figure 7:
Explanatory diagram 1 showing the cutting points for the failure surface test: Main body base material 2
: Partition part 3: Heat-resistant ring 4: Notch part 5: Split core 6: Split core 7: Mating surface 10-14: Main mold core 14: Sprue 15: Runway 16: Weir 20: Thermocouple

Claims (1)

[Claims] Only the tip of the partition part 2 inside the scroll formed at an acute angle is made of a heat-resistant material made of a material with excellent heat resistance and abrasion resistance. In a variable capacity turbine housing in which the ring 3 is integrally formed by casting, the heat-resistant ring 3, which has one or more notches 4 on the outer circumferential surface 3a cast into the main body base material 1, is degreased. After cleaning, the heat-resistant ring is roughened by blasting, clamped at a predetermined position on the mating surface 7 of several split scroll cores, and cast by a vertical casting method. Casting method for turbine housing.