Establishment of Resistance Seam Welding Technology for Stainless Steel Foil Materials

Shion Koyama･Ryo Konno･Souichiro Nishino (Ibaraki University)･Seiya Yoshikawa (ART-HIKARI)･Tetsuya Nogami･Reina Araya (NOGAMI)

The use of stainless steel foil material is being considered to achieve both thin-wall and lightweight designs in battery systems. In this study, resistance seam welding was applied to stainless steel foil materials ranging from 200 μm to 20 μm, and joint strength and fracture morphology were investigated. Although sufficient joint strength was achieved for all thicknesses, it was found that the fracture morphology and joint morphology differed depending on the thickness.

Development and Performance Evaluation of Hermetic Seals using Plastic Flow Joining

Taketo Nakajima･Kaoru Mannami･Souichiro Nishino (Ibaraki University)･Ryo Tominaga･Naonori Ishii (Aoyama Seisakusho Ibaraki Factory)

Hermetic seals using plastic flow bonding are attracting attention in battery components for electric vehicles. However, the cost is high due to tight dimensional tolerances. The objective of this study was to produce a hermetically seal that can maintain its performance even when the dimensional accuracy is made rough. The roughness of dimensional accuracy was reproduced by increasing the clearance between parts, and the airtightness and strength of the seal were examined.

A Study on Causes and Prevention of Wheel Bolt Loosening in Heavy Duty Vehicles

Soichi Hareyama･Ken-Ichi Manabe･Satoshi Kobayashi (Tokyo Metropolitan University)

Accidents involving wheels falling off of large vehicles continue to occur. Related organizations have instructed the need for proper tightening torque management and retightening. This study examines the causes of wheel bolt loosening based on the properties of the torque method (Calibrated wrench method), and examines and proposes a loosening prevention method. When tightening with a torque wrench, the initial axial force obtained varies from 1.4 to 3, depending on the lubrication conditions. This means that some bolts have an initial clamping force of 90% of the yield clamping force when tightened with many wheel bolts, but some bolts have only 30% of the yield clamping force. It is possible that sufficient clamping force cannot be obtained even if retightening is performed. This suggests that the torque method should be used in conjunction with an effective loosening preventing methods or devices in the prevention of wheel bolt loosening.

Effect of Shot Peening Treatment on the Formation of Hydroxide Film and Bending Strength in Cast Magnesium Alloy

Kento Tamura･Souichiro Nishino (Ibaraki University)･Daisuke Suzuki (Yamanashi Industrial Technology Center)

Magnesium hydroxide film in hydrothermal treatment improves the corrosion resistance of magnesium alloys, but non-uniformity of the film has been a problem in cast magnesium alloys. In this study, we proposed a method to form hydroxide film that gives corrosion resistance evenly by shot peening treatment of die-cast magnesium alloy.

Technology to Improve the Durability of Coating Dies in Press Working of Al Alloys

Ryu Yoshiura･Souichiro Nishino (Ibaraki University)･Yukitaka Sumiya (Japan Coating Center)･Minoru Kouta (Yamanoi Seiki)

In this study, we evaluated the durability of coated dies in a lubricant-free press work test of Al alloys. In order to suppress the adhesion of Al alloy in the die damage mechanism, we selected a coating focusing on the surface characteristics of the coating. As a result, the use of a DLC coating suppressed adhesion in the press working of Al alloys.

PVD Coating to Improve Die Durability in Press Working of 1470MPa Class High Tensile Strength Steel

Ryutaro Kanazawa･Nanako Seki･Souichiro Nishino (Ibaraki University)･Yukitaka Sumiya (Japan Coating Center)･Minoru Kouta (Yamanoi Seiki)

As steel is becoming stronger and stronger from the viewpoint of weight reduction of car bodies, the life of press dies is becoming a problem. Press dies are coated to improve their service life, but not many coatings have been developed for the recently developed 1470 MPa class high tensile steel. In this study, we propose a PVD coating that improves the durability of dies based on the number of layers in a multi-layer coating and the difference in hardness between the layers.