Chip adhesion preventing device for preventing adhesion of chips to drill shank

A chip adhesion preventing device is capable of preventing chips from adhering to the drill shank of a drill held on a spindle (1) included in a boring machine. Fluid passages (17, 23) are formed in the spindle (1) and a work holding member (19), respectively, and nozzle holes (18 and 22) are formed in the spindle (1) and the work holding member (19) so as to be connected to the outlet ends of the fluid passages (17 and 23), respectively, and to be directed toward the shank (13) of the drill (3). A high-pressure fluid is jetted through the nozzle holes (18, 22) toward the drill shank (13) to blow off chips (15) adhering to the drill shank (13).

BACKGROUND OF THE INVENTION 
The present invention relates to a chip adhesion preventing device for 
preventing the adhesion of chips to a drill shank of a drill used on a 
boring machine for boring a workpiece by rotating the drill. 
A chip adhesion preventing device for preventing the adhesion of chips to a 
drill shank of a drill used on a boring machine for boring a workpiece by 
rotating the drill is disclosed in, for example, JP-A No. 3-3713. 
Referring to FIG. 3 showing this prior art chip adhesion preventing 
device, a drill 3 is held by a chuck 2 on the extremity of a spindle 1. A 
cylindrical pressure foot 4 is disposed so as to surround the extremity of 
the spindle 1 and a pad 5 is attached to the outer surface of the bottom 
wall of the pressure foot 4. The pressure foot 4 is held with the lower 
surface of the pad 5 pressed against the upper surface of a protective 
plate 7 mounted on a printed wiring board 6 to press the printed wiring 
board 6 against a lower plate 8. 
An air passage 9 is formed in a lower portion of the pressure foot 4, and a 
discharge opening 10 is formed in a portion of the side wall of the 
pressure foot 4 on a side opposite the side of the air passage 9. The air 
passage 9 is connected to a compressed air supply device, not shown, and 
the discharge opening 10 is connected to a suction device, not shown. An 
air passage 11 is formed in the pad 5 so as to be connected to the air 
passage 9 of the pressure foot 4. A nozzle 12 continuous with the air 
passage 11 opens in the inner circumference of the pad 5. In FIG. 3, 
indicated at 13 is a drill shank. 
While the boring machine provided with the chip adhesion preventing device 
thus constructed is in operation, high-pressure compressed air supplied 
from the compressed air supply device flows through the air passage 9 of 
the pressure foot 4 and the air passage 11 of the pad 5 into the nozzle 
12, and is blown at a high pressure through the nozzle 12 against the 
cutting drill body 14 of the drill 3 to cool the drill 3 and to remove 
chips 15 from the drill 3. Chips 15 blown off the drill body 14 of the 
drill 3 are sucked together with air by the suction device and are 
discharged outside through the discharge opening 10 of the pressure foot 
4. 
Although chips 15 adhering to the drill body 14 can be removed from the 
drill 3, chips adhering to the shank 13 cannot be removed. Some of the 
chips 15 adhering to the shank 13 are caused to drop onto the drill body 
14 by the vibrations of the drill 3 and damage the bore and the workpiece. 
If many elongate cuttings wind around the shank 13, it is possible that a 
tool post is broken during automatic tool changing operation. Therefore, 
the boring operation needs to be interrupted frequently to remove chips 15 
adhering to the shank 13, which reduces the efficiency of the boring 
machine remarkably. 
SUMMARY OF THE INVENTION 
Accordingly, it is an object of the present invention to solve the 
foregoing problems in the prior art and to provide a chip adhesion 
preventing device capable of preventing the adhesion of chips to a drill 
shank. 
According to one aspect of the present invention, a chip adhesion 
preventing device for preventing the adhesion of chips to a drill shank 
used on a boring machine for boring a workpiece with a rotating drill 
comprises: the spindle of the boring machine, provided with a fluid 
passage, and a nozzle for blowing a fluid against the drill shank to 
remove chips adhering to the drill shank, connected to the fluid passage 
and having an axis directed toward the drill shank, and the work holding 
member of the boring machine, provided with a fluid passage, and a nozzle 
for blowing a fluid against the drill shank to remove chips adhering to 
the drill shank, connected to the fluid passage and having an axis 
directed toward the drill shank. 
The chip adhesion preventing device of the present invention blows the 
fluid supplied into the fluid passages of the spindle and the work holding 
member of the boring machine through the nozzles connected to the fluid 
passages against the drill shank to remove chips adhering to the drill 
shank. Thus, the chip adhesion preventing device of the present invention 
is capable of easily removing chips adhering to the drill shank by the 
pressure of the fluid to enable the boring machine to form a clean bore 
without damaging the bore with chips. Since the drill shank is cleared of 
chips, an operation for inserting the drill shank into a drill post during 
an automatic drill changing operation can be accomplished with improved 
reliability. Since the boring machine need not be stopped to remove chips 
adhering to the drill shank, the efficiency of the boring machine is 
improved greatly. 
Since the chip adhesion preventing device of the present invention needs 
only to blow the fluid, the chip adhesion preventing device of the present 
invention can be fabricated at a very low cost.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Preferred embodiments of the present invention will be described 
hereinafter with reference to the accompanying drawings, in which parts 
like or corresponding to those of the prior art chip adhesion preventing 
device previously described with reference to FIG. 3 are designated by the 
same reference characters. 
Referring to FIG. 1 showing a chip adhesion preventing device in a first 
embodiment according to the present invention, a drill 3 is held by a 
chuck 2 on the extremity of a spindle 1 included in a boring machine. A 
fluid passage 17 having an axis parallel to that of the spindle 1, and a 
nozzle 18 connected to the fluid passage 17, having an axis inclined at an 
angle to the axis of the spindle 1 and directed toward the shank 13 of the 
drill 3. 
A work holding member 19 has a cylindrical portion and a reduced 
cylindrical portion projecting downward from the lower wall of the 
cylindrical portion. The work holding member 19 is disposed with the lower 
end of the reduced cylindrical portion thereof pressed against the upper 
surface of a protective plate 7 mounted on a printed wiring board 6 to 
hold the printed wiring board 6 on a lower plate 6. 
The reduced cylindrical portion of the work holding member 19 is provided 
with a lower fluid passage 20 having an axis perpendicular to the axis of 
the work holding member 19, connected to a compressed air supply device, 
not shown, and a lower nozzle 21 connected to the lower fluid passage 20 
and opening in the inner circumference of the reduced cylindrical portion. 
The upper cylindrical portion of the work holding member 19 is provided at 
a position corresponding to the shank 13 of the drill 3 with an upper 
fluid passage 23 having an axis parallel to that of the lower fluid 
passage 20, and an upper nozzle 22 directed toward the shank 13 and 
opening in the inner circumference of the cylindrical portion. The fluid 
passage is connected to the compressed air supply device, not shown. A 
discharge opening 10 is formed in the side wall of the upper cylindrical 
portion of the work holding member 19 on a side opposite the side of the 
upper nozzle 22. The discharge opening 10 is connected to a suction 
device, not shown. 
When starting the boring machine for a boring operation, the compressed air 
supply device is actuated to supply compressed air into the fluid passages 
17, 20 and 23, and the suction device is actuated. The spindle 1 is 
lowered, and the work holding member 19 is pressed against the upper 
surface of the protective plate 7 to press the printed wiring board 6 
against the lower plate 8 to form a bore in a predetermined portion of the 
printed wiring board 6 with the drill body 14 of the drill 3. Although 
chips 15 produced by cutting the printed wiring board 6 adhere to the 
drill body 14 of the drill 3, the chips 15 adhering to the drill body 14 
are blown off the drill body 14 by the high-pressure compressed air blown 
through the nozzle 21. The chips 15 blown off the drill body 14 are sucked 
into and discharged outside through the discharge opening 10 by the action 
of the suction device. 
Chips 15 adhering to the drill shank 13 and those going to adhere to the 
drill shank 13 are blown off the drill shank 13 by the high-pressure 
compressed air blown through the nozzles 18 and 22, and discharged 
outside. Thus, the adhesion of the chips to the drill shank 13 can be 
prevented. 
A liquid, such as a cutting liquid may be used instead of compressed air. 
FIG. 2 shows a chip adhesion preventing device in a second embodiment 
according to the present invention. The chip adhesion preventing device 
shown in FIG. 2 is similar in construction to the chip adhesion preventing 
device in the first embodiment, except that the former is not provided 
with any fluid passage corresponding to the fluid passage 17 and any 
nozzle corresponding to the nozzle 18. A compressed air supply device and 
a suction device are operated to supply compressed air into fluid passages 
20 and 23, and to discharge the compressed air supplied to the chip 
adhesion preventing device. High-pressure compressed air is blown through 
a nozzle 22 against the drill shank 13 to blow chips 15 adhering to the 
drill shank 13 and those going to adhere to the drill shank 13 the drill 
shank 13 off by the high-pressure compressed air blown through the nozzle 
22. Thus, the adhesion of chips 15 to the drill shank 13 can be prevented.