Retrofit Puts Electronic Control into Multiple Spindle Automatics
A retrofit drive package from SKI Industries Inc (Shelby Township, MI) for multiple spindle automatic screw machines uses an electronically programmable, servo-controlled power feed and spindle drive to control the spindle and cam shaft drives.
According to Dennis Haller, SKI president and co-author of the SKI patent, the new drive package has been retrofitted to a number of Acme and Cone six- and eight-spindle automatic screw machines that are operating in the field. Some of these machines are producing a wide variety of hose fittings; others various fastener nuts, and two are producing input shafts for steering gears.
"This is the definitive programmable retrofit drive system in the market today. With the advanced features of servo-controlled feeds and servo-controlled spindles, the manufacturer and operator have the needed flexibility for fast setup, fine tuning, and easy changeover," Haller says.
Typically, most automatic screw machines provide rotational power to the spindles and the cam shaft drive through a complex series of gears, shafts, and clutch systems. These components also provide synchronization between the rotation of the spindles and the rotation of the cam shaft drive. Drawbacks inherent with these conventional designs are usually associated with the inflexibility of the machine. They can't handle a variety of different parts. Changeover and setup time is usually substantial requiring changeover of high/low drive gears, spindle change gears, and feed gears.
SKI's new patented retrofit package provides a design that simply and effectively retrofits multiple spindle automatic screw machines with an electronic control system. The mechanical portion of the retrofit can be performed in a matter of hours: the control part can be done in a day or two.
Gears, shafts, and clutch system are replaced with the following:
• A variable speed drive motor to provide rotational power to the main shaft;
• A chain drive system that consists of two sprockets that are placed on the existing spindle drive shaft and connected with a chain to allow the elimination of the high and low speed gear change sets;
• An electronic encoder that is directly attached to the main pulley shaft for monitoring the rotational speed of the spindle shaft and providing that information to the central processing unit;
• A worm gearing assembly that provides a sufficient gear ratio to reduce the rotational speed at which the electric servomotor unit operates while providing sufficient power to rotate the drum. It also provides inertial dampening, reducing the load on the electric servomotor.
• A central processing unit that synchronizes the speeds of the variable speed motor and electric servomotor.
The retrofit package requires minimum alteration of the original machine to provide electronic programmable feed and speed controls that allows:
• Infinite levels of speed and feed
• Infinite numbers of part programs
• Faster setup and changeover times
• Power reverse capabilities
• Fine feed settings as low as 0.0005 ipm
• Fine speed settings within 5 rpm
An extensive reduction in common replacement parts is achieved. Included are components like clutches, brake bands, feed change gear shafts, spindle change gear shafts, roll clutches, bevel gears, spindle speed or feed gears, high and low speed dogs and 90% of the bearings.
A manual hand crank is provided as standard so the machine can be easily moved forward or reverse without power. A handwheel on the control panel is provided for easy setup and fine tuning.
SKI Industries Inc provides diversified services for the screw machine industry, including complete rebuilding, remanufacturing, and special tooling packages for all makes of multi-spindle automatic machines.
SKI Industries Inc, 14665 23 Mile Road, Shelby Twp, MI 48315-3001; phone: 810-247-7100