Connecting the Dots: Machining from Every Angle

MTConnect is a set of open, royalty-free standards intended to foster greater interoperability between controls, devices and software applications by publishing data over networks using widely accepted XML and Internet Protocol technology. When serving as a complete communications standard, this “plug-and-play” networking platform assists factories in calculating overall equipment efficiency, monitoring all equipment from one system, reducing production losses and identifying lean manufacturing strategies.

CNC turning centers, machining centers and peripheral equipment from Doosan Infracore America Corporation (Pine Brook, NJ) are now MTConnect compliant. This means shops can now “connect the dots” for a competitive advantage in vertical, horizontal and universal machining by integrating these machine tools through this networking platform. “Our partner for MTConnect is TechSolve of Cincinnati,” explains Hwankui (Henry) Kim, the director/engineering supervisor at Doosan Infracore America. “By establishing an open and extensible channel of communication for plug-and-play interconnectivity between devices, equipment and systems, MTConnect allows sources to exchange and understand each other’s data.”

This common communication provides shop managers with near real-time data from throughout their factory that can be used to develop applications for more efficient operations, improved production and increased productivity. The following vertical, horizontal, and universal machining centers are examples of new machine tools that can be integrated with MTConnect.

MULTI-PURPOSE VERTICAL MACHINING
The Doosan VCF850LSR is a vertical machining center that uses a traveling column with a tilting spindle B-axis head to process a wide range and large capacity of parts. It utilizes up to five axes simultaneously for machining multiple sides of a work piece all at once. The head can rotate 110 deg on either side of vertical, enabling the VCF 850LSR to machine large and complex parts in a single setup, eliminating costly fixtures and downtime.

The supplied D500 (500 mm / 19.685 in) rotary table allows access of up to five sides of a part for machining on multiple faces of the work piece without having to re-fixture. This allows for reduced number of setups and much higher precision of the finished component. With 4 + 1 axes of simultaneous motion, very complex shapes can be produced, and when coupled with the machine’s ability to rotate the spindle head (+110 deg / -110 deg), it is possible to machine five sides of a work piece in a single setup.

The bed is a rigid, one piece casting made from fine grain Meehanite cast iron with heavy ribbing to help prevent vibration and deformation during heavy cutting. Extra wide spacing of the roller guide ways provide for excellent support of the saddle regardless of the load distribution on the table, which is fully supported by the saddle in all positions with no overhang.

Through the superior traveling column design, the table (and therefore the work piece) remains locked during machining to provide a uniform load to the guideways, ball screws and motors. All axes are of a Roller Linear Motion Guide type for higher stiffness, accuracy, and surface finish than other more commonly used Ball Bearing Guide types. These are both heavy duty (X –  45 mm / 1.772 in, Y – 45 mm / 1.772 in, Z – 45 mm /1.772 in) and widely spaced (X – 655 mm (x2) / 25.787 in, Y – 720 mm / 28.346 in, Z – 560 mm / 22.047 in). Roller guide ways are three times more rigid, with two times more life than ball bearing guide ways to provide for optimal weight and force distribution.

Each axis is driven by a high precision double nut ball screw that is centered between the guide ways and supported on both ends by angular contact thrust bearings. All ball screws are cooled by circulated, refrigerated oil at all critical components including the ball nut, support bearings and the motor housing. This system, coupled with a double pretension design, provides outstanding positioning repeatability with virtually no thermal growth.

All axes have large diameter ball screws (X – 63 mm / 2.480 in, Y – 50 mm / 1.968 in, Z – 50 mm / 1.968 in) that are directly connected to oversize AC servo drive motors without gears or belts in order to help eliminate backlash. The X, Y and Z axes utilize absolute type linear glass scales for higher positioning accuracy that do not require referencing at power up. The scales virtually eliminate the impact of slides and ball screw thermal expansion and backlash. This improves the ability to hold tight part tolerances with fewer offset changes.

The powerful, 12,000 rpm built-in drive spindle motor has 18.5 / 22 kW (25 / 29.5 hp) and 147.25 nm (108.60 ft-lb) of torque that promotes thermal stability and keeps vibration at higher rpm to an absolute minimum. A refrigerated cooling control system circulates cooling oil around the spindle in order to maintain a constant temperature, increasing accuracy regardless of the ambient temperature of the cutting conditions.

The CAT 40 Big Plus spindle system is a true cartridge-type unit supported by high precision, permanently grease lubricated ceramic ball bearings with a spindle acceleration / deceleration time of 0 – 12k (1.3 sec) / 12k – 0 (1.5 sec). An encoder is attached to the spindle to allow rigid tapping, further increasing productivity. The headstock is mounted to a rigid swiveling base that is driven by a heavy duty and high precision worm gear. This allows the spindle to present tooling to the work piece at any angle between +110 deg to -110 deg from vertical, enabling machining on multiple sides of the work piece at once.

The B-axis is capable of 900 ft-lb of torque during contour machining or can be locked down by means of a hydraulic piston with 1,475 ft-lb of torque for heavy duty cutting. Oil cooling around the assembly maintains constant temperature, regardless of the cutting condition, to ensure accuracy. The Big Plus spindle system and tooling surpasses all other spindle concepts through simultaneous taper and flange contact between the machine spindle and tool holder, as well as complete interchangeability with existing machines and tools.

Upon mounting the tool holder into the machine spindle, contact occurs prior to clamping. Due to the retention force, the taper of the tool holder expands the machine spindle in its elastic range. The tool is pulled further in until the tool flange touches the spindle face for maximum rigidity. The 60 tool chain type Double Arm ATC is servo motor driven and provides reliable exchange of tools, with a tool-to-tool time of 1.5 seconds. A dedicated positive displacement pump delivers the coolant directly to the tool tip. The immediate benefit is more aggressive feeds and speeds can be maintained throughout the cutting process. There is no need to stop and adjust coolant nozzles, which increases both in cut time and operator safety.

Protecting the spindle and the vital rotary union from contamination is a Cyclone filter that does not require the use of bags, reducing maintenance costs and downtime. The 360 L (95 gal) tank stores an ample supply of coolant and is isolated from the machine bed to help prevent heat transfer. The hand held Manual Pulse Generator lets each axis move in increments of x1, x10 or x100, making fixture or part alignment quick and easy. The 10 ft cord gives full access to the machine and the magnetic back allows for one-handed operation, with the MPG being conveniently held in place on the machine table or guarding.

The keyed switch enables the protection mode for both the program and offset data. Removing the key limits access to only authorized personnel. In the unprotected position the key cannot be removed and all data is available for edit. The Fanuc 31-iB series control is equipped with a slot for a PCMCIA and USB port on the control next to the display. A PCMCIA memory card can be used to upload and download programs as well as drip feed directly from the card. Programs running from the card will take the same time to run as a program that is stored in the control memory.

It is possible to search through and restart anywhere in a program as long as it contains line numbers. The USB Port does not allow you to drip feed; it is only for uploading and back up of programs and parameters. The control is mounted on a pendant that can be positioned anywhere along the door opening via a rail and can swivel up to 180 deg. This allows the operator a clear view of the working area wherever the work piece is positioned or machining is taking place.

COMPACT, HIGHLY PRODUCTIVE HORIZONTAL MACHINING
The HC 400 II horizontal machining center delivers high speed, high precision and high productivity in a compact platform designed for shops with limited space. Its versatile 12,000 rpm spindle motor excels under a wide range of machining applications. With its integrated rotary pallet changer and advanced technological features, the HC 400 II provides impressive performance at an exceptional value.

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The bed is a rigid one-piece casting made from fine grain Meehanite cast iron that is used for its excellent dampening and vibration absorbing characteristics. It is heavily ribbed in order to withstand deformation under heavy cutting loads. The rigid box-type column casting is heavily ribbed to prevent twisting or distortion under stressful machining processes. Massive guide ways support the column for maximum rigidity. The saddle is fully supported for the full length of travel with no overhang to ensure maximum rigidity and precision.

The HC 400 II comes standard with a rotary shuttle type Automatic Pallet Changer. The APC is rigidly built and has a large working area able to accommodate work pieces up to 600 mm (23.6 in) diameter x 800 mm (31.5 in) high (with no hydraulic interface installed). Qualified edge locators are included to aid in fixture or tombstone setup. The pallet is located by four highly precise, tapered conical pins and then locked into place by pull studs to insure maximum precision and rigidity.