QUICK ON THE DRAW

Essex Machine Tool Services (New Britain, CT) rebuilds and remanufactures conventional vertical turret lathes to CNC and also provides spare parts for the time-honored line of Bullard vertical turret lathes. With a crew of 20 employees that includes engineers, master machine builders and electrical techs, this shop is run by Dana Budney and Chester Perry under a single motto, ?Buy the best and build the best.?

The company specializes in the remanufacturing of vertical turret lathes from the ground up, saving only the old quality cast iron frame and incorporating all new spindle drive systems, tool changers, ram/drawbars, axis positioning, new hydraulics, lube systems and other components in the process. ?Sometimes,? remarks Budney, ?customers will pay up to 30 percent more for a new machine over the cost of a remanufactured machine which has the same functions. But the remanufactured machine can outperform the new machine for less money.?

In the past, that wasn?t always the case. But today, with the advanced CNC, motor, drives and technology available, a machine can actually be made to run better than when it was new. ?Superior positioning and new way liner materials with heightened feedback and accuracy make the remanufactured vertical turret lathe technology advanced in a way that was simply impossible in bygone days,? recalls Budney. He also notes that the master machine tool builders, electrical techs and engineers on his staff bring this scenario to life, through their skills, ingenuity and years of experience.

Another of the key components used here to achieve the highest levels of functionality on the remanufactured VTLs is an advanced power drawbar from OTT-Jakob (Lengenwang, Germany), a leading supplier in Europe that has been represented in America for nearly 30 years by Advanced Machine & Engineering Co. (AME; Rockford, IL). AME manufactures precision spindle interface components and workholding devices and is also the home to many top names in the machine tool industry, including the current OEM for the VTLs
remanufactured at Essex, namely, the DeVlieg-Bullard Services Group, now part of Bourn & Koch (Rockford, IL).

By using this relatively new power drawbar design, according to Budney, the VTL can be modified for use with virtually any tool clamping system, including HSK, KM and 50 or 60 taper. This marks another example where the remanufactured vertical turret lathe with the advanced drawbar actually brings the machine tool to a higher level of performance than when it was new.

The universal inside spindle contour was an important step toward achieving totally modular tooling, as it allows this rebuilder and its customer the flexibility to use different steep taper HSK 60 tools with air blast coolant-thru functionality, by simply exchanging the gripper unit. Since the ram unit is stationary and the work table rotates on the VTL, hydraulic and air lines are likewise stationary in this application. AME also designed a unique front and rear insert to accept the gripper unit without removing the drawbar from the ram. With the drawbar in place in the ram, the changeover of gripper units could be done quickly and with assured proper positioning. To further aid the position integrity, the drawbar also provides a signal ring to sense positioning.

Lastly, another supplier innovation was designed into this drawbar assembly. An intensifier mechanism (shown in cutaway) amplifies the pull force to 3½ times greater than the spring stack, which allows the drawbar?s use in a considerably smaller space. Given the massive size of this ram and the weight of the tooling involved, this represents a significant design and performance advantage for Essex, according to chief engineer Paul Vitols.

Harold Goellner, the product manager for the spindle interface group at AME, explains further. ?Essex presented us with some very different challenges, since they have been remanufacturing vertical turret lathes that are both old and are no longer manufactured by the OEM. However, through our relationship with the Bullard people here in Rockford and our experience working on their machines over the years, we were able to make certain modifications to the power drawbar to ensure its suitability for the remanufactured vertical turret lathes being done at Essex.?

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Essex Machine Tool Services, 221 South Street, Building E8, New Britain, CT 06051, 860-223-5488, Fax: 860-223-5484. Contact Essex at [email protected].

www.ame.com