Section 3. Research and Development of Basic Technology
Item 3. Specialty Steel Research and Development and Forging Technology Research
The greatest problem for the advancement of the automotive business was the absence of steel materials suited to automotive manufacturing. High quality steel products were supplied for weapons use in ships and aircraft, but steel materials suited to the mass production of automobiles had not been developed. Despite requests for development made to steel manufacturing companies, due to the limited consumption none of the companies would undertake the work.
Kiichiro Toyoda consulted Dr. Kotaro Honda1 of Tohoku Imperial University in Sendai to ascertain whether Japan had the steel manufacturing technology to enable the manufacturing of steel materials for automotive use. He then proceeded to arrange for the construction of a steelworks and, in January 1934, the Toyoda Automatic Loom Works, Ltd. Steelmaking Department was established.2 After completion of the steelworks building in July that year, operation of a 2-ton electric furnace was commenced in September and a 4-ton electric furnace in October, with installation of a merchant mill completed in November.
In addition, Kiichiro's acquaintance, Dr. Ryonosuke Yamada of the Tokyo Institute of Technology-who was familiar with material testing-was asked to propose plans for materials testing facilities for the Steelmaking Department. Based on his advice, facilities were introduced for the testing and analysis of prototype steel materials, and specialty steel research commenced.
In developing the new types of steel, the steel was first tested in the research laboratory's 5 kilograms high-frequency induction furnace. In the testing of the prototypes, after meeting the target properties, the prototypes were forged from steel ingots into successively larger electric furnaces then, following quality confirmation, manufactured in a 2 or 4-ton furnace.
At first, simple types of steel were produced. Starting with structural carbon steel SA1 (equivalent to the current S25C3) used for loom materials, and proceeding to the similar structural carbon steel SA2 (equivalent to the current S40C), case hardened carbon steel SA9 (equivalent to the current S15CK) and various types of steel such as spring steel SS4 and carbon tool steel SB2 and 3 (currently SK3 to SK6), were developed.
The Toyoda Automatic Loom Works Steelmaking Department aimed to manufacture steel materials suited to the mass production of automobiles?in other words, durable steel materials with good machinability, and consistent quality and dimensions. The Department later expanded its production capacity due to the increase in Toyota automobile production. However, the Steelmaking Department was spun off in 1940 to make use of the benefits of being a licensed company under the Steel Manufacturing Industries Law. In this way, Toyoda Steel Works, Ltd. was established on March 8, 1940. In November 1945, its name was changed to Aichi Steel Works, Ltd.
Shortly prior to the establishment of Toyoda Steel Works, Ltd., from January 1940 to the end of that year, U.S. engineer Louis Henry Berry provided advice at the steelworks.4 He was an engineer who came to Japan to provide technical advice on the U.S. made electric furnace introduced by Nihon Spindle Manufacturing Co., Ltd.5, and was also an expert on steel manufacturing technology. Shoichi Saito6 served as an interpreter and assistant for the obtaining of the engineer's advice.
After the establishment of the Toyoda Automatic Loom Works Steelmaking Department, production of prototype forged parts for use in automobiles was commenced using three free hammers (2 ton, 1 ton and 1/2 ton), which were also used as forging equipment in the manufacturing of spinning and weaving machinery. Subsequently, in the year leading up to the start of 1935, the equipment was increased by four closed die forging stamp hammers (two 1 ton, one 1/2 and one 1/4 ton), used for the stamp forging of automobile parts. In 1937, another 2-ton free hammer was added.
In the forging of the crankshaft for the Model A six-cylinder engine, after preforming it into a crude form using a 1-ton free hammer, the crankshaft was forged using a 2-ton free hammer with a forging die attached. However, the 2-ton equipment was inadequate for the purpose, so the forging die was divided into two parts and performing conducted twice. The forging die was then completed by molding the two parts into a single piece.
There was also a problem with the fabrication of the pins joining the crankshaft and connecting rod. It was necessary to make 120 degree angles (which could currently be accomplished simply by a twisting process) but at the time there was no specialized equipment. Consequently, it was very difficult work, and an overhead traveling crane was used to raise the pin and make the angle.7
In the Steelmaking Department's forging plant, prototypes of forged parts for automobiles were progressing. In addition to crankshafts, parts including camshafts, connecting rods, valve rocker arms, push rods, differential ring gears and rear axle shafts were successfully manufactured. When the Model A1 prototype passenger car was finished in May 1935, all of its forged parts were made in the forging plant.