MHI Develops “BH50-17” Double-headed Helical Broaching Machine Achieving High Speed and Outstanding Precision

Helical broach machines are machine tools that perform machining of internal helical gears, i.e. ring-shaped gears with oblique tooth leads on the inner surfaces. The helical broach cutters, a long bar-shaped cutting tool, draws material out of a workpiece as it rotates, to form an oblique tooth leads.

The BH50-17 was developed to meet usage conditions in Japan and Asia based on a model that Federal Broach has already delivered in significant volumes primarily to the leading U.S. automakers. The adoption of 52-kilowatt (kW) high-power motors enables broaching at a rate of 25 tons per axis, while the adoption of a square (box) guide in the straight axis has enhanced mechanical rigidity and achieved high-speed, high-precision machining. The BH50-17 also features two servo motors that enable independent control of two tables, a configuration that permits simultaneous double-headed machining of two different workpieces. The achievement of a compact machine enables easy installation without a pit. The maintenance ease of the machine also has been enhanced through adoption of a crane for changing two different types of tool that enables smooth tool changes, as well as thorough cutting dust treatment, etc.

Helical ring gears form the outer ring of planetary gears. They are expected to come into increased demand as automobile automatic transmissions, hybrid vehicle gearboxes, stepless (continuously variable) transmission systems, etc. become increasingly complex and production volumes expand. Helical broach machining is well suited to high-speed, large-volume production of internal gears, and also makes for easy quality control. Because workpiece finishing is significantly affected by factors such as precision of the helical broach cutters, related manufacturing expertise and compatibility with the broaching machine, companies capable of supplying broach cutters and broaching machines as a set are in a prime position to take the lead in market competition.

Federal Broach is one of the world’s leading producers of both broach cutters and broaching machines. Roughly 80% of the company's sales presently derive from the North American and European markets. In view of the potential for growth in the Chinese and Southeast Asian markets, MHI took the decision to transfer Federal Broach's technologies to its Machine Tool Division's Main Plant in Ritto City, Shiga Prefecture. Preparations are now going forward toward increasing production and expanding sales, and the development of the BH50-17 is the first step in preparing products suited to the newly targeted markets.

The new BH50-17 will be introduced in a panel display at the forthcoming Japan International Machine Tool Fair (JIMTOF) to take place at Tokyo Big Sight (Ariake) from October 30 through November 4.

MHI is one of only a few companies in the world that handle both gear cutting machines and their cutting tools. By augmenting this strength with superiority in the supply of both broaches and broaching machines enabled by the company's link with Federal Broach, going forward MHI will adopt an aggressive approach to the development of diverse products and solutions for use on manufacturing floors around the world.