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Drilling and tapping, close center, in-line hole patterns

Close center, spindle patterns for drilling and tapping in-line hole patterns are a specialty of Zagar Inc. Standard, gearless, crank driven spindles are frequently applied to a standard industrial spacing of .625" - .625" - .500" between holes. In-line patterns (rows of holes) vary in length to greater than 6 feet. These long rows of holes are machined by Zagar, multiple spindle tooling in several stages or in a single pass. The multiple spindle system shown below machines 96 holes in a single operation. There are two rows of spindles with forty eight spindles in each row. In this case, the holes are tapped. Tool holders are quick-change standards. All 96 spindles are tied into a single-crank, drive train to insure mechanically synchronized rotation of each spindle. All 96 spindles start and stop at exactly the same time. All of them also turn the same exact amount of degrees and revolutions. The simplicity of this multiple spindle drive train, is the heart of it's perpetual performance.

A Zagar standard, N/C controlled, production, drilling and tapping machine is combined with the above 96 spindle head. The complete system is shown in the following photos. Simple, menu driven (available with English or Spanish menus) operator interface enables changing over the system for either drilling or N/C rigid tapping cycles. Combination drilling and tapping cycles are also a pre-programmed, menu selected option for the efficient operation of combination drill / tap tooling (draps). Standard, menu selected options include variable spindle RPM, tapping any inch or metric thread pitch, and tapping either right or left hand threads.

Re-circulating, self-contained, filtered coolant system is shown mounted underneath the machine table. A separate, automatic, flow-thru oiling system pumps filtered oil thru the 96 spindle head . The oil system includes an electric flow valve. The machine is automatically shut down if oil flow is not detected. The oiling system assures long-term, uninterrupted operation of the 96 spindle head. All 96 holes are tapped in less than 5 seconds.

Drilling and tapping are separate cycles in the adjacent heads. Two 21 spindle rows of drills and two 21 spindle rows of taps (84 spindles total), are fed into the work piece using a Zagar, 7.5 HP, MQ60, ball screw actuated, quill feed unit. In turn, the N/C control of the ball screw unit features a program option for dividing a cycle into separate drilling and tapping stages. Once the drills have fed thru the wall of the work piece, the program automatically changes to a rigid tapping stage. All 42 tools either drill or tap a hole each cycle. A total of five stations (420 spindles) were applied on a single machine system.

Single pass tapping of a long, in-line hole pattern is performed by the following machine. It features 135 spindles on the earlier mentioned 5/8", 5/8", 1/2" spacing. Non-cutting form taps are used at each spindle. The gearless, crank drive is applied to insure the spindle to spindle synchronization with this system's mechanical, lead screw feed. Two lead screws are also tied into the main, crank drive system to feed the work piece into the form taps. Lubricating coolant flowed on the taps thru the long brush shown in front of the main head.

Length of the 135 spindle pattern made it possible to tap a complete 72" long row of holes in one pass. The spindles are all spaced on the repeating 5/8", 5/8", 1/2" distances between holes. Because of the crank drive design, any single spindle is inter-changeable with any other. Tool holders are Zagar, quick-change standards. The entire row of taps can be replaced in less than 10 minutes. Lubricating oil constantly flows in thru the top of the head and out thru the bottom. Except for the sound of the spindle motor and the taps forming the threads, the operation is silent (no gears). Every moving part of the multiple spindle head, is within a lubricated bearing.

There are Zagar projects where only one hole is drilled or tapped at one time. Our production hole making systems vary in the number of holes machined but are consistently used to mass produce holes on a production basis. Crank driven, gearless, multiple spindle heads make it practical to apply a substantial number of spindles to any hole pattern. Accordingly, long, in-line hole patterns and Zagar multi-spindle heads, are a natural combination to maximize hole making capacity and efficiency.