JPH0549419B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a method for repairing fluid leaks in cast parts, and mainly relates to a method for repairing fluid leaks in cast parts, and is mainly concerned with repairing the surface of parts of equipment for handling fluids formed of light metal castings such as aluminum and zinc. This invention relates to a method for repairing fluid leaks in cast parts, which makes it possible to eliminate fluid leaks from the parts by very easily closing internal defective holes that have occurred in the past.

[Technical background of the invention and its problems] Conventionally, in casting metals, especially light metal castings such as aluminum and zinc, residual air in the mold, molten metal gas, lubricant combustion gas, etc. are generated during cooling of the molten metal. Internal defect pores formed by release to the outside have become a major problem.

In other words, these internal defects occur due to the reasons mentioned above, and although research is being conducted on casting methods and production control techniques to eliminate these causes, at present, internal defects occur during the casting process. It was impossible to eliminate all holes.

Therefore, when parts such as housings of devices that handle fluids such as water, oil, and air, such as pumps, are formed from the above-mentioned castings, the fluid is under high pressure, so there is a serious defect that the fluid leaks from internal defective holes. This occurred and became a very big problem.

Therefore, conventionally, as a countermeasure for this internal defect hole,
As shown in FIG. 4, the entire cast product 11 is inspected for flaws, and then a sealing agent such as water glass is applied to the internal defect hole 12 discovered by this inspection.
Repairs have been carried out by impregnating and inhaling porosity from the surface into the interior, or by filling and adhering a sealant 13 such as metal powder with an adhesive. Therefore, this inspection and repair requires a lot of time, leading to an increase in costs, and also has the disadvantage that it can peel off due to corrosion, deterioration, etc., or peel off due to temperature expansion, rust, etc.

[Object of the Invention] In view of the above-mentioned drawbacks, the present invention has been made to solve internal defects exposed on the surface of cast parts used in devices that handle fluids in a very simple manner, and moreover, by sealing them using conventional pore sealing methods. It was created with the aim of allowing faster sealing compared to repair methods such as impregnating with agents, inhaling, filling and adhesion, etc.

[Summary of the invention] In order to achieve the above-mentioned purpose, this invention provides water,
Ultra-fine particles with a particle size of 100μ to 20μ are used to seal the internal defects that have occurred up to the surface of the cast parts of equipment that handles fluids such as oil and air. By intensively spraying small spherical shot particles toward the area where internal defects exist, the compressive residual stress is maximized at a depth of 100μ to 20μ from the surface, and its residual stress is reduced. The process consists in sealing the hole by causing a return phenomenon due to stress and a collapse phenomenon at the entrance of the internal defect hole.

[Embodiments of the Invention] The details of the present invention will be described below with reference to the drawings.

Reference numeral 1 in the figure is a cast part, and this cast part 1 has internal defects that occur due to residual air, molten metal gas, lubricant combustion gas, etc. in the mold (not shown) being released to the outside. Hole 2 is present. These internal defect holes 2 occur more often in light metal castings such as aluminum and zinc than in iron castings.

As mentioned above, the surface of this light metal casting has minute irregularities and the internal defect hole 2 is exposed to the surface.
As mentioned above, these are generated when gas or the like is released to the outside, so most of them are minute through-holes. Therefore, if the cast part 1 with the internal defect hole 2 exposed on the surface is used as a housing part of a device such as a pump that handles fluids such as water, oil, and air, the fluid will be under high pressure. Therefore, it is natural that fluid leaks from the internal defect hole 2.

Therefore, an attempt was made to close the internal defect holes 2 by performing shot blasting on the surface of the cast component 1 in which the internal defect holes 2 were exposed to the surface.

However, the diameter of the smallest shot particles currently used for shot blasting is approximately 0.2 mm to 0.3 mm. This 0.2mm~
Even if shot blasting is performed using shot particles of about 0.3 mm, it will not be possible to crush and close the opening of the internal defect hole 2, and the shot particles themselves will be too large, causing damage to the surface of the cast part 1. In many cases, the shot grains do not hit the internal defect holes 2 due to the minute irregularities of the holes, and in fact, this is not done at all.

Therefore, we use shot grains 3, which are made into spherical shot grains, and further reduce the diameter to 100 μm or more.
When shot blasting was performed intensively as ultra-fine particles of 20μ, as shown in Fig. 1, the shot particles 3 hit the vicinity of the internal defect hole 2 or the opening entrance part, and the opening entrance part contracted. Now it is possible to seal the hole.

That is, when the ultra-fine spherical shot particles 3 are struck against the surface of the cast part 1, compressive residual stress is generated inside the surface of the cast part 1, and its return phenomenon causes the surface of the cast part 1 to contract at the entrance of the internal defect hole 2. This means that the

However, when we conducted various experiments, we found that when the shot grains are large, the impact of hitting is too large or the shot is rough, and compressive residual stress occurs at a depth of about 200μ or more from the surface of the cast part 1, as shown in Figure 3. Although the surface of the cast part 1 is hardened, the location where the compressive residual stress occurs is too deep, causing internal defects in the hole 2.
It is not enough to shrink and close the surface part of the .

On the other hand, the diameter of the spherical shot grains 3 is set to 100μ~
Assuming ultrafine particles of 20μ, as shown in Figure 2,
The impact of the hammering is not so large and dense, and the compressive residual stress is at its maximum at a distance of approximately 20 to 100 μ from the surface of the cast part 1. As a result, the opening entrance portion of the internal defect hole 2 contracts due to the return phenomenon due to the compressive residual stress near the surface of the cast part 1, and the opening entrance portion of the internal defect hole 2 contracts by hitting the spherical shot grains 3. Together with the slight crushing, the surface opening of the internal defect hole 2 can be closed.

In this case, polygonal shot grains 3 have a grinding effect and are less effective in generating compressive stress, and the dimensions after shotplast processing will change, so spherical shot grains 3 are preferable. The particle size is preferably about 80μ to 50μ. Furthermore, since the locations where defects occur in cast parts are almost constant, it is desirable to process those locations intensively over time, and for this purpose, air nozzle blasting is desirable;
It is not limited to this.

In Figs. 2 and 3, the vertical axis shows the residual stress, and the horizontal axis shows the depth from the surface of the cast part 1. The + side of the residual stress is the tensile residual stress, and the - side is the compressive residual stress. Shows residual stress. or,
Figure 3 is a diagram when using shot particles with a large diameter of 0.4 mm, where numeral 4 indicates shot particle injection pressure of 3.5 kg/cm ² , 5 indicates injection pressure of 4.5 kg/cm ² , and 6 indicates the residual stress when the injection pressure is 5.5 kg/cm ² and 7 indicates the residual stress when the injection pressure is 6.3 kg/cm ² .

Next, an example of actual shot blasting will be shown. The residual stress in this case is as shown in FIG.

Shot blasting equipment...Direct pressure air blast machine Target parts...Water pump housing (aluminum casting) Water pump cover (aluminum casting) Oil pump housing (zinc casting) Conditions...Air pressure 5Kg/cm ² Nozzle diameter 7mm Projection material Stainless steel beads #150 Average particle diameter 74μ Projection distance 200mm Projection time 6 minutes As a result, the fluid leakage rate was 0.1 to 1.0cc/min without the above shot blasting process, but with this shot blasting process, all The amount of fluid leaked was 0, indicating an excellent sealing effect.

In addition, when such shot blasting is applied, it is possible to seal the pores and remove processing burrs from the product.Furthermore, the surface becomes hard due to work hardening, increasing the strength of the product and promoting beautification. Therefore, it is now possible to obtain a product with a very good surface in a shorter time than with conventional repair methods such as impregnating with sealant 13, inhaling, filling adhesive, etc.

In this case, if the material of the spherical shot grains 3 is stainless steel beads, rust will not occur, so that the spherical shot grains 3 can last a long time and improve the quality of the product. However, in addition to this, the material of the spherical shot particles 3 may be aluminum or zinc beads, iron beads, and glass beads.
If the diameter is about 100μ to 20μ, other materials can also be used.

Further, it goes without saying that the conditions for shot blasting are not limited to those in the above embodiments, and must be set appropriately each time. In this case, the shot projection time is 5 to 5 minutes for normal surface finishing, blasting for deburring, etc.
In contrast to this, the shot blast sealing process in the present invention takes a longer time of around 6 minutes and is carefully performed.

[Effect of the invention] According to the invention configured as described above, water,
In order to seal the internal defect holes 2 that have occurred in the cast part 1 up to the surface, a particle size of 100 μm or more is applied to the surface of the cast part 1 of a device that handles fluids such as oil and air, which has minute irregularities. By intensively spraying 20μ microscopic spherical shot particles 3 toward the area where the internal defect hole 2 exists, the compressive residual stress at a depth of 100μ to 20μ from the surface is maximized. By causing a return phenomenon due to the residual stress caused by the residual stress and a collapse phenomenon at the entrance of the internal defect hole 2, the hole is sealed. The compressive residual stress generated in
It exists at a depth deeper than 200μ, and the surface of the cast part 1 is uneven when viewed under magnification, so the shot particles with a large diameter will not hit the internal defect hole 2 because the unevenness will get in the way. Although it may not be possible to shrink and close the opening of the internal defect hole 2, since the spherical shot particles 3 with an ultra-micro diameter of 100μ to 20μ are sprayed intensively, they are larger than the shot particles with the large diameter. 100μ~ from the surface of the cast part 1 because the impact of hitting is relatively small and dense.
Compressive residual stress is generated at a depth of 20μ, and the return phenomenon due to the compressive residual stress causes the internal defect hole 2 opening entrance to contract, and in addition, the internal defect hole 2 opening entrance is also slightly crushed, so it is easy to do. It is possible to close the opening of the internal defect hole 2.

Moreover, unlike the conventional method of filling the pores with a sealant 13 such as water glass, it is possible to seal the pores very easily and reliably, and in this process, the location where the internal defect hole 2 occurs is shaped like the cast part 1. Therefore, instead of inspecting all products, only the first product is inspected for flaws, and that area is intensively subjected to shot blasting using the ultrafine particles, and then the next product is inspected. If shot blast sealing is performed intensively on similar areas without flaw detection, impregnation, inhalation, and
Compared to repair methods such as filling and adhesion, anyone can carry out the repair in an extremely short time, and it is possible to completely eliminate fluid leakage from the product.

Furthermore, as a secondary effect, it is possible to obtain a surface that is extremely excellent as a product, such as removing processing burrs on the product, increasing strength by processing and hardening the surface, and promoting beautification.

As explained above, according to the present invention, it is possible to reliably close internal defective holes that occur in cast parts using a very simple method. Leakage can be completely eliminated, and furthermore, it is possible to remove processing burrs from the parts, improve strength by work-hardening the surface, and promote beautification at the same time.
Compared to conventional repair methods using sealant impregnation, inhalation, filling adhesive, etc., anyone can carry out the repair in an extremely short time, so it has various excellent effects such as reducing processing costs. It is something that plays.

[Brief explanation of drawings]

FIG. 1 is an enlarged sectional view of a main part of a product obtained by an embodiment of the present invention, and FIG. 2 is a diagram showing residual stress of a product processed by an embodiment of the present invention.
FIG. 3 is a diagram showing the residual stress when shot blasting is performed using large-diameter shot grains, and FIG. 4 is an enlarged sectional view showing the state of hole sealing by the conventional method. DESCRIPTION OF SYMBOLS 1... Casting part, 2... Internal defective hole, 3... Spherical shot grain, 11... Casting product, 12... Internal defective hole, 1
3...Sealing agent.

Claims (1)

[Claims] 1. On the surface of a cast part of a device that handles fluids such as water, oil, and air, which has minute irregularities, a particle size of 100 μm to By intensively spraying 20μ microscopic spherical shot particles toward the areas where internal defects exist,
Fluid leakage of a cast part characterized by making the compressive residual stress maximum exist at a depth of 100μ to 20μ from the surface and causing a return phenomenon due to the residual stress and a collapse phenomenon at the entrance of an internal defect hole to seal the hole. Repair method.