US machine tool manufacturer Bourn & Koch, Inc. has implemented advanced CNC systems from NUM to extend its competitive edge in the market by using state-of-the art machine control software.
Following a highly successful project to migrate control of powerful 7-axis horizontal gear hobbers to NUM’s Flexium CNC platform, the company is now standardising on this control technology for an extensive range of its gear production machines.
Bourn & Koch chose to upgrade to NUM’s Flexium CNC on its 25H - 400H Series II gear hobbers, starting with the 400H. The speed and power of this machine means that it can replace as many as seven older style gear production machines, making it a popular choice with companies machining large precision components such as bull and cluster gears, worms, shafts, splines and pinions.
Bourn & Koch has partnered with NUM Corporation for over 25 years and uses NUM’s CNC systems in many of its gear shaping, hobbing and grinding machines, as well as in various metal removal machines in addition to numerous CNC upgrade and machine retrofit projects. Both the company and their customers benefit from this collaboration; jointly-developed conversational software has been cited by a number of Bourn & Koch customers as a factor in their machine purchasing decisions.
The HMI on the 400H gear hobber maximises use of the software’s capabilities by combining a conversational style dialogue with powerful graphics, allowing the operator to work without having to use or even have knowledge about ISO languages. To produce a part, the operator simply enters machine setup information such as cutting speeds, work piece and tooling geometry via simple menus, while graphical images provide clear and unambiguous views of the hob tool and resultant gear part. All calculations involved in creating the machine control program for a particular part are handled automatically by the software.
The company decided to migrate the design to NUM’s Flexium CNC platform as a matter of course. Tim Helle, President of Bourn & Koch, explains that they offer customers a choice of CNC systems with NUM provided as standard on most of their gear hobbers. The company follows a policy of using the latest technology to maximise the performance and cost-effectiveness of their machines, an approach that also results in progressively simpler machine operation with less need for training, and means that spares are readily available, which contributes to machine uptime and reduces customers’ support costs.
Moving to NUM’s Flexium CNC platform also provided technical advantages with the system’s faster block processing and loop update times offering the opportunity to reduce the machine’s cycle time and further improve its accuracy. Additionally, Flexium also features more on-board NC memory, a much wider and unified set of PLC software development tools and increased freedom for OEMs to create application-specific HMIs. This additional control and HMI customisation flexibility allowed Bourn & Koch to enhance various aspects of the gear hobber’s operation.
When the latest 400H Series II gear hobber is offered with NUM CNC, the entire machine is based on NUM motion control technology, with the sole exception of its (C axis) work piece spindle motor, which is a special liquid-cooled direct drive unit capable of generating 560 Nm of torque at 110 RPM. In addition to a Flexium 68 NCK (numerical control kernel) and its associated PLC, NUM is supplying all the I/O, drives and servomotors that are used on the machine.
NUM Corporation also provided technical support to Bourn & Koch in the transition from Axium to Flexium CNC system. Bourn & Koch has already started using this CNC platform across their range of gear hobbers and plans to eventually offer NUM’s Flexium CNC technology on all their new gear hobbing machines.
All seven axes of the gear hobber, including the work piece spindle motor, are controlled by the Flexium 68 CNC and NUMDrive C servo drives. The radial (X) and axial (Z) feed axes, as well as the hob head shift (Y), hob head swivel (A) and tailstock (W) axes, are all programmable and are driven by NUM BPH series medium inertia servomotors. The hob cutter spindle (B axis) is driven by an asynchronous NUM AMS motor fitted with a high resolution multi-turn encoder, controlled by a NUMDrive C servodrive; a further NUMDrive C module controls the machine’s direct drive work piece spindle motor.
For simplicity and ease of operation, the 400 H gear hobber is equipped with a NUM FS152i operator panel and keyboard, mounted on the front external face of the machine with an ergonomic swing arm. The panel combines a 15-inch touch sensitive screen with an integrated industrial PC running the Windows Embedded operating system, equipped with a solid state disk and dual core processor to provide a fast and responsive HMI. A number of machine functions, such as positive/negative jog and speed override of selected axes, together with emergency stop, can also be controlled remotely using a cable-linked portable hand wheel.
The machine utilises the full four-axis electronic gearbox capability of NUM’s popular gear hobbing solution, NUMgear to help speed production of complex gear parts. In conjunction with built-in high-speed synchronisation facilities this allows the axial and radial feeds, and the hob head shift axis, to be geared to the work piece spindle. Use of the electronic gearbox is entirely automatic with the machine operator merely needing to enter basic gear manufacturing data, such as the number of teeth, the number of tool starts, the gear module and the helix angle to define and activate a specific electronic gearing function.
Tool wear management is also prioritised with the software continuously monitoring the condition of the hob tooling and employing a pre-programmed tangential hob shifting sequence to ensure that an efficient cutting edge is always engaged during gear generation. The entire process is automatic and can even be invoked during a machine cycle, prompting the operator whenever it is time to check or replace the hob. Undamaged hobs can be reground or recoated many times before they are worn out, which helps to minimise tooling cost. Hob head synchronisation is maintained throughout the shifting process to minimise disengagement/re-engagement times and prevent tool or work piece damage.
Bourn & Koch also makes use of the software’s non-contact automatic gear alignment feature to improve throughput on the 400H, by enabling a work piece that already has teeth to be automatically synchronised to the cutting threads of the hob cutter.
Describing Bourn & Koch as one of their most valued customers and a key business partner, Steven Schilling, General Manager of NUM Corporation in Naperville, Illinois comments that the machine tool manufacturer has a large installed base of customers using machines equipped with NUM’s CNC systems, many of whom regard ease of operation as a prime machine tool differentiator.
Following the implementation of Flexium, NUM is now in the process of increasing the level of in-depth product training provided for Bourn & Koch’s engineering, machine start-up and customer support teams.