MULTI-SPINDLE DRILL HEAD
It is recommended to read DESIGN OF MULTI-SPINDLE DRILL HEAD WITH DIFFERENT PITCH HOLES before reading this article.
The whole setup consists of the following parts
Top plate 1
Top plate 2
Gear assembly ( 1 main gear and 4 secondary gears)
Adjustable Transmission Systems (ATS)
Bottom plate 1
Slots – 4
Body for the 4 slots
Bottom plate 2
The shank is placed above the top plate 1 and is connected to the main gear. A bearing 6204 Z connects the main gear and the shank. The secondary gears are connected to the top plate 1 and the Adjustable Transmission Systems using bearings 6203 Z. the gear arrangement is placed between the top plates. The secondary gears are connected to the ATS using shafts of diameter 16 mm.
The ATS, which is the most important transmission tool used, consists of an adjustable torsional shafts fitted with universal joints at both the ends. 4 such ATS are used for each secondary gear. The lower end of each ATS is
connected to a body with the help of 6202 Z bearings. The body are placed in the slots provided in the bottom plates 1.
The bottom plate 1 has 4 main slots in which the body can move with additional slots at each side of the main slot. The secondary slots are used to adjust the body. The body are provided with nut and bolt arrangement. The drill chuck in the main slot can only be moved when the bolt and nut in the secondary slots are adjusted. The bottom plate also has markings for various PCD’s. The top plate 2 and the bottom plate 1 are held together using studs and nuts.
A shaft of diameter 12 mm is connected through the body on which the drill chucks are placed. The drill chuck is of M10 gate and the range of drill tool diameter is from 1.5 mm to 10 mm.
The bottom plate 2 is connected to the bed of the drilling machine and it is used to support the spindle head as well as absorb the vibrations.
TRANSMISSION OF POWER:
When the motor is switched on the power is transmitted to the main spindle which in turn transfers it to the primary gear. Due to the arrangement of the gears, primary gear transmits the power to the secondary gears. This causes the shafts of the gears to rotate. Since each gear shafts are connected to the universal joints the power is transferred to it. These universal joints are placed at both the ends of an adjustable shaft. Since universal joints are used, the power can be transmitted even if the angle is varied. The power is then conveyed from the joints to the collets using shafts that are placed in slots of the bottom plate.
MACHINING FOR A GIVEN PCD
The screws are loosened and the collets are adjusted as per the given PCD (the given PCD should be within the given range). Then the screws are tightened and depending on the type of machining the drill tool is attached in the collet. When the given PCD is within the lower range the machining done is similar to that of the fixed multi spindle drill head. Here the collets are closer to each other at the front of the slots.
Now when the PCD is at the higher end, the adjustable shafts come into play because the length of the shaft has to be extended to meet the desired range. Hence the use of universal joints are crucial for the transmission of power at different angles. The collets are adjusted and placed at the far end of the slots away from each other. The range of PCD is from 80 mm to 220 mm.
The Fabricated multi drill spindle head can drill 4 holes at a time and the pitch circle diameter can be varied from 40 mm to 120 mm. Since this setup is small and portable, it can be mounted on the drilling machine. The construction is simple and can employ semi-skilled labours. This multi spindle drill head will also be useful to reduce the operation costs, eliminate the non-value added activities and increase the productivity of small and medium enterprises.