Wednesday, November 15, 2023

JPMA Announces Design Winners

2023 JPMA AWARD

DEVELOPMENT PRIZE

A. NEW DESIGN

A-1 Practical Application of High Frequency & High Strength Reactor Core
FINE SINTER CO.,LTD.
Daido Steel Co., Ltd.

This product is a reactor core installed in the power control unit (PCU) essential for electric vehicles. Recently, there has been a demand for reactor cores with high insulation properties that can support higher frequencies in systems aimed at miniaturization. With conventional soft resin insulation films, the main problem is when the resin film deforms during pressure molding, making it improbable to calculate insulation distance. In this development, we solved this problem by developing a powder with an aluminum oxide insulationfilm and a glass coating, and by developing a heat treatment (degreasing mechanism) and succeeded in commercializing a reactor core with high insulation and strength.

In the production of the powder with Al2O3film, there was an issue in which the formation of aluminum inclusions inhibited atomization during the atomization process. So, we introduced a large-scale gas atomization equipment that can melt the metal in an inert atmosphere, making stable production possible. In addition, with the oxidation heat treatment process, we have developed a new method with optimal conditions that results in a low iron (Fe) loss and reduced inductance variation to stabilize atmospheric Al2O3 film thickness for mass production of the powder.

Lastly, regarding reactor core manufacturing, the molded products were chipped when using conventional magnetic conveyance equipment due to low molded strength. Thus, we have developed new conveyance equipment, optimizing the gripping force, position, falling height, angle, etc. resulting in a 50% reduction in cycle time compared to conventional production lines.

In order to achieve high strength, low melting point glass is softened, cooled and solidified through heat treatment. However, the degreased gas inhibits the adhesion of the glass and reduces the strength. To avoid it, a new mechanism that the exhaust route of the evaporated degreased gas is kept constant as it is and decomposes only outside the furnace.

Moreover, by implementing unmanned operations from powder molding to packaging process, we achieved a 40% increase in productivity.

A-2 Development of High-Precision Parts for New Mechanism Semi-Active Suspension
FINE SINTER Co., LTD.

This product is a piston and a pilot case used for a new mechanism of semi-active suspension for large SUVs. The installed unit performs even more precise damping force control to improve off-road performance and vehicle stability. The damping force control valve, which used to be on the outside, is now built into the shock absorber, that saves space and reduced weight.

The built-in valve mechanism consists of 3 components; the piston is sandwiched between the 2 pilot cases s. Furthermore, a narrow and complex oil passage is arranged inside and is subject to high internal pressure, so each component requires high sealing performance, rigidity, and precision.

The piston's diagonal ports (oil passages) are often processed by machining, but we molded them by placing the piston's oil passages on the end face out of phase, and then assembling two identical parts. On the other hand, there were concerns about buckling due to stress concentration during assembly due to the complex structure, so we adopted Fe-Cu-C material, which is more rigid than conventional Fe-C material. However, the trade-off to the high rigidity was that the straightening performance during recompression decreased, so we took measures using CAE analysis to optimize the product and mold shape. This significantly reduced machining and succeeded in reducing costs. In addition, we suppressed the variation in the direction of molding compression, which increased due to the complexity of the shape, by strengthening control using a special jig, and achieved the strict requirement of an assembly clearance of 10 μm or less.

By optimizing the shape of the seat surface and compression die of the pilot case and satisfying the high required accuracy, we were able to successfully incorporate a control valve, contributing to a 20% reduction in unit volume and a 30% weight reduction.

A-3 Oil-Impregnated Bearing Unit for CPAP Equipment that Achieves Low Sliding Loss at High Speeds
Porite Corporation

This bearing unit is used in CPAP (Continuous Positive Airway Pressure) devices that are considered effective for the treatment of sleep apnea syndrome. CPAP device is a device that suppresses non-respiratory conditions by sending pressurized air from the nose to the airway and spreading the airway. A blower motor is used to introduce the pressure air, and it is necessary to adjust the discharge rate of the air according to the breath, and high responsiveness to follow the high-speed rotation of the motor is required. In addition, as it is used close to the human body, it requires low noise and long life.

The reduction of shaft vibration is important for low noise, and reduction of clearance between the shaft and the bearing is considered to be effective. On the contrary, sliding loss is caused by an increase in fluid resistance, so we have succeeded in reducing sliding resistance to the maximum extent by developing a bearing with a medium relief shape that relieves the central part of the shaft sliding surface and a fine dimple on the sliding part. In addition, we keep working to reduce sliding loss through the combined use of low-viscosity ester-based oil.

We also had concerns about a decrease in the viscosity of the impregnated oil due to frictional heat during high-speed rotation. We optimized the bearing material and suppressed the oil leakage scattered through the shaft by using a sintered seal cap and solved this problem. The seal cap is impregnated with oil repellent and is placed on the end face of the bearing to serve as a lid to prevent oil leakage. Reduction in oil consumption is directly linked to product life, which contributes to longer product life.

We have succeeded in commercializing oil-impregnated bearing units for CPAP equipment replacing conventional ball bearings.

A-4 Development of Long/complex Shape Rotor and Slide for Variable Displacement Vane Pumps
SUMITOMO ELECTRIC INDUSTRIES, LTD.

These parts are rotor and slide for variable displacement vane pumps that improve the efficiency of large engines. The focus of the development was to satisfy the demand for larger capacity by increasing the overall part length and lower loss by using thinner vanes. The total length of these parts is 40mm, which is approximately 50% larger than conventional parts by reason of the need for a large discharge volume for the pump function. Accordingly, the following various measures were taken to meet the pump specifications.

Considering the density balance, the tool punches for compacting the rotor are usually divided into 2 punches due to the inner concave shape of both end faces. However, the slits for the vanes would result in a disconnected structure for the operating punches, which could increase the risk of tool breakage. As a countermeasure to this, we focused on the fact that the concavity remains the same level (4 mm) even though the overall length is larger than that of conventional parts, and we adopted non-divided single upper and lower punches. In addition, due to the extremely narrow slit width (1.8 mm), in the conventional method of compacting the slits using side cores fitted to a die, the tools were damaged owing to side resistance when the green compact was ejected. Therefore, we have developed a method of embedding side cores in the die using double shrink fitting based on FEM analysis, which enabled mass production of rotor.

The slide requires a high degree of peripheral contour despite the long/complex shape, which necessitated designing tools based on appropriate prediction of dimensional changes in each process. There are two points of reference for a slide: a center for position adjustment and a rotor eccentric point. The conventional tool setting based on one point, the rotor eccentric point of the slide, caused scratch problem of products in sizing process. Therefore, we considered the tool settings based on the above two reference points according to actual use and satisfied the high precision requirements of the slide.

In conclusion, we have succeeded in developing sintered parts for variable displacement vane pumps for large engines, which contributes to the improvement of fuel efficiency and CO2reduction.

D. NEW POWDERS

D-1 Aluminum Bronze Powder for Powder Metallurgy
FUKUDA METAL FOIL & POWDER CO., LTD.

Aluminum bronze is a copper alloy with high strength, heat resistance, corrosion resistance, and wear resistance, and is widely used in ships and mechanical parts. Many of aluminum bronze parts are manufactured using casting method and are then machined to improve dimensional precision.

On the other hand, to manufacture aluminum bronze parts using powder metallurgy practically has been difficult because alumina layer is formed on the powder surface and prevents sintering.

In this development, we removed the alumina layer as AlOF gas by adding AlF3 as a sintering aid to the Cu-Al alloy, which was the raw material powder, and succeeded in promoting diffusion among powder particles and sintering the aluminum bronze. Furthermore, we added CaF2, which forms a liquid phase with AlF3, to enhance the action of the sintering aid and improve sinterability.

Nevertheless, this powder required sintering in pure H2, and was impractical. Therefore, we added Cu-P to improve sinterability and achieved sintering in a low H2 concentration atmosphere. As a result, it has become possible to sinter the aluminum bronze in a low H2 concentration atmosphere including N2, and the mass productivity of it has been improved.

Now, this powder is adopted in bearings for automobile fuel pumps, which are used in environments immersed in fuels such as gasoline and is expected to be used for biofuels and synthetic fuels in the future. Additionally, by the addition of "aluminum bronze" as a new material selection for powder metallurgy, it is expected to apply it to the fields that require corrosion and wear resistance.

F. EFFORT PRIZE

F-1Sintered Parking Parts for Electric Vehicles
SUMITOMO ELECTRIC INDUSTRIES, LTD.

We conducted the development of sintered parking-support used in the parking lock mechanism of BEV transmissions. The parking-support works in the following mechanisms: when the transmission shift lever is placed in the park position, the mating part (parking wedge) rides on the tapered part of the parking-support and pushes up the parking pawl, which locks the parking gear and fixes the axle.

Initially, the customer gave the end face of the parking-support a concave shape, which necessitated compacting with divided tools to adjust the density balance. However, there were disadvantages of compacting with divided tools, including concerns about the tool damage and difficulty in ensuring flatness. Accordingly, we proposed to the customer to reduce the stepped surface; we enabled the addition of a concave shape of the parking support parts with an integrated tool.

Another issue was the strict specification of parallelism for the end face of the part due to mounting a leaf spring to the surface. In the conventional method, this specification could be met only by machining. Nevertheless, an extremely uniform density distribution ensured parallelism without machining by applying powder scraping technology and adding a powder relief shape, including the introduction of the integrated tool mentioned above. In summary, we have accomplished mass-production of sintered parts without machining.

F-2 Oil-Impregnated Sintered Bearings with Excellent Wear Resistance by Applying Density Gradient
Porite Corporation

Cooling water for automobiles, as demand for low fuel consumption and low exhaust gas has increased in recent years. A valve-open/close motor (water-cooled open/close, VG turbo/ EGR) is installed to precisely control the flow rate of cooling water/gas. This bearing is used for that motor.

The valve switching motor is used in a wide temperature range with high vibration. Therefore, the durability evaluation is based on the temperature. Heat cycle test to apply vibration while moving from-40°C to 160°C. Abrasion resistance and Low-temperature noise suppression was required as a function.

The material of this product has been selected as a Cu-Fe-Sn-C-P material primarily composed of copper-coated iron powder with a proven track record in automotive components, supplemented with graphite. We ensured wear resistance, frictional performance, and lubrication by coating the surface with copper over an iron skeleton and incorporating solid lubrication through graphite. To ensure stable supply of lubricating oil from high to low temperatures, we introduced a density gradient, with higher density on the inside and decreasing towards the outside, maintaining the oil content while controlling the oil supply from the sliding surface. We created a density gradient by incorporating a convex shape near the inner diameter of the bearing end face and compressing it appropriately during re-compression.

The outer diameter side serves as an oil tank, and oil is supplied to the inner diameter side by the capillary force generated by the density gradient.

As a result, the formation of an oil film on the inner diameter surface is accelerated and the sliding characteristics are improved. The recompression increased surface hardness of bore diameter and improved wear resistance.

The impregnated oil meets the requirements for a wide temperature range by adopting a fluorine oil with little evaporation under high temperature and with reduced viscosity rise under low temperature.

As a result, we have succeeded in applying oil-impregnated sintered bearings to valve open/close motors.

The material of this product has been selected as a Cu-Fe-Sn-C-P material primarily composed of copper-coated iron powder with a proven track record in automotive components, supplemented with graphite. We ensured wear resistance, frictional performance, and lubrication by coating the surface with copper over an iron skeleton and incorporating solid lubrication through graphite. to ensure stable supply of lubricating oil from high to low temperatures, we introduced a density gradient, with higher density on the inside and decreasing towards the outside, maintaining the oil content while controlling the oil supply from the sliding surface. We created a density gradient by incorporating a convex shape near the inner diameter of the bearing end face and compressing it appropriately during re-compression.

The outer diameter side serves as an oil tank, and oil is supplied to the inner diameter side by the capillary force generated by the density gradient. As a result, the formation of an oil film on the inner diameter surface is accelerated and the sliding characteristics are improved. by the recompression effect Increased surface hardness of bore diameter and improved wear resistance.

The impregnated oil meets the requirements for a wide temperature range by adopting fluorine oil with little evaporation under high temperature and with reduced viscosity rise under low temperature.

As a result, we have succeeded in applying oil-impregnated sintered bearings to valve open/close motors.

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JAPAN POWDER METALLURGY ASSOCIATION
MatsudaShoji Bldg.
3-42-7, Taito, Taito-ku, Tokyo 110-0016
URL: https://www.jpma.gr.jp/ E-mail: info@jpma.gr.jp

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