# Patent

## Title
Drill/countersink assembly and method for producing countersunk holes

## Abstract

A countersink cutter or assembly for countersinking to precise depths in various applications, including aerospace applications, uses a pneumatically driven pistol grip motor attached to a countersink tool assembly. The countersink tool assembly, which has a multi-fluted cutter, is coupled to and is coaxial with the spindle. The cutter can be preset to a precise depth at the back end of assembly through the slot using a gage.

## Background
This application claims priority on U.S. provisional patent application No. 61/378,127, which was filed on Aug. 30, 2010, which is incorporated by reference.


BACKGROUND
A countersink operation may be accomplished using microstops that may need frequent adjustment. In some processes, cylindrical holes are drilled in to a substrate, e.g. non-metallic material, like composite or metallic material, like aluminum and titanium and then countersinking a hole using a countersink tool secured in microstop. During this countersink operation, the pilot of the countersink (that has a frusto conical shaped cutting member with cutting edges), is inserted in to hole and motor is turned on. The microstop can require multiple adjustments as the tool is used over time. There have been many tools developed for specific needs that are very sophisticated and use hydraulics, pneumatics and electronics, etc. Such tools may be generally cumbersome and heavy.
Usually, the inspection of holes is done on test panels placed on work benches near production area. This adjustment and checking of countersink depth several times before starting on production panels requires manpower and time. The depth of countersunk hole should be checked after every few holes during production to ensure more consistent countersink depth. When the cutter is replaced, the position of cutting edge is usually not as the same position in relation to the front surface of the microstop and hence further adjustments of the microstop may be necessary.
Accordingly, there is always a need for an improved countersink device, assembly and method. It is to these needs, among others, that this disclosure is directed.
SUMMARY
This disclosure includes a countersink assembly adapted to be attached to a drill motor for drilling and countersinking a hole in a workpiece. The assembly has (a) an approximately cylindrical rear subassembly extending between a first end and a second opposed end and (b) an approximately cylindrical front subassembly having a main body, a spindle with a spindle shaft. The subassembly moves laterally in relation to the rear subassembly. An approximately cylindrical countersink cutter, operably connected to the drill motor, has a coaxial spindle having a bore to accommodate cutter shaft, a nose piece, and cutting edges.
Another embodiment includes a method for adjusting a countersink assembly which includes:

    
    
        a) providing a countersink assembly adapted to be attached to a drill motor for drilling and countersinking a hole in a work piece,
        b) setting the front subassembly at a desired distance from the rear subassembly; and
        c) locking the front assembly in place with a gage.
    
    


Certain embodiments provide a method for quickly dismantling the front portion of the front subassembly to expose the cutter for quick replacement. The front subassembly can be dismantled very conveniently to replace the cutter. This feature can be achieved by guiding the main body into the guide plate and rear subassembly and “clocking” both parts such that they are secured by spring pressure from three (3) ball plungers at about 120 the contact surfaces of degree apart in the main body which creates uniform spring pressure between the main body and nose piece. This can be achieved by other means such as designing parts to accommodate magnets in both adjacent parts and providing means of alignment or by simply using screws to fasten the two parts or by using the principles of cam action.



BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 shows one embodiment of the assembly of the power tool consisting of the front and rear subassemblies along with a cutter and a vacuum hose.
FIG. 2 shows an exploded view of the complete assembly shown in FIG. 1 of the countersink power tool consisting front (moveable) and rear (stationary) subassemblies.
FIG. 3 shows an exploded view of the rear subassembly with, shown in FIG. 1, power tool, shown in FIG. 1, with three jaw chucks, an adapter sleeve, an adapter and a vacuum sleeve without a vacuum bag.
FIG. 4 shows an exploded view of the front subassembly consisting of a main body, a guide plate, a nose piece, spindle with cutter and the details inside the adapter along with vacuum hose.
FIG. 5A shows one embodiment of the assembly having a cutter and a spindle.
FIG. 5B shows a detailed view of the cutter.
FIG. 5C shows a more detailed view of the countersink cutter and spindle as assembled.



DETAILED DESCRIPTION
This disclosure is directed towards a countersink cutter, countersink assembly and method for countersinking that can be used to cut holes to precise depths in various applications, including aerospace applications, using a pneumatically driven pistol grip motor attached to a countersink tool. The countersink tool assembly, which has a multi-fluted cutter, can be coupled to and is coaxial with the spindle. The cutter can be preset to a precise depth at the back end of assembly through the slot using a gage. The setting of the tool can remain relatively constant even when a cutter is replaced by another new cutter or another cutter. In addition, the cutter has a quick change mechanism in which the shaft of the cutter is coupled to the spindle coaxially through cam action provided inside concentrically where the cutter is secured to the spindle and drives it. Similar rotary tools such as drills, screw drivers, counterbores and the like are rendered useable with the adapting mechanism and providing concentricity and torque because of cam action provided by the spindle and the cutter shaft surfaces. This principle of setting up the depth from the back end of tool and quick change concept of assembly tool for cutter replacement; and quick change features of the cutter and spindle engagement including tools other than countersink cutter replacement can be very conveniently adapted to pneumatically driven right angle power tools and stationary machines and other machines where the machine has movable spindle heads.
One embodiment includes a countersink assembly adapted to be attached to a drill motor for drilling and countersinking a hole in a workpiece. As shown in FIG. 1, the assembly has an approximately cylindrical rear subassembly (stationary) extending between a first end and a second opposed end and having a slot for a gage. The outer diameter of the assembly defines an approximate cylinder. The rear subassembly is mounted on the drill motor with an adaptor sleeve; The assembly also has a approximately cylindrical front subassembly having a main body, a spindle with a spindle shaft. The subassembly moves laterally in relation to the rear subassembly. An approximately cylindrical countersink cutter, operably connected to the drill motor, having a coaxial spindle having a bore to accommodate cutter shaft, a nose piece, and having cutting edges. The spindle shaft mounts into the drill motor. The cutter shaft has a flat front end and a flat back end along a longitudinal axis, an angular flat surface, and the groove accommodates an O-ring. The front end of the cutter shaft coincides with the back end of body diameter of the cutter. The angular flat surface locks into a pin of the spindle; and the intersection of the longitudinal axis and the cutting edges, when projected on to the longitudinal axis, is held in alignment at a substantially constant distance from the back surface of the cutter. The distance between the spindle and the nose piece are constant and equal to the distance between the back flat surface and the center of the radius between the tangent of pilot diameter and the cutting edges.
Another embodiment includes a method for adjusting a countersink assembly which includes:

    
    
        d) providing a countersink assembly adapted to be attached to a drill motor for drilling and countersinking a hole in a work piece;
        e) setting the front subassembly at a desired distance from the rear subassembly; and
        f) locking the front assembly in place with the gage.
    
    


Certain embodiments provide a method for quickly changing dismantling the front portion of the front subassembly to expose the cutter for replacement. The front subassembly can be dismantled conveniently to replace the cutter. This has been achieved, in part, by guiding the main body into the guide plate and nose piece subassembly and “clocking” both parts in such a way that they get secured by the spring pressured three ball plungers at about 120 degree apart in the main body, which creates uniform spring pressure between the main body and nose piece contact surfaces. This can be achieved by other means such as designing parts to accommodate magnets in both adjacent parts and providing means of alignment or by simply using screws to fasten the two parts or by using the principles of cam action.
Main Assembly
Referring to FIG. 2, the rear subassembly consists of a pistol grip motor 101 (or spindle motor 101) has a Jacob chuck 202 secured to it. This chuck can also be substituted by some colleting arrangement for securing the spindle 218. The adapter sleeve 103 that has internal threads circumferentially is mounted on to the motor 101 via threads after sliding over the chuck 202. The adapter housing 104 is attached to the pistol grip motor 101 sliding over the adapter sleeve 103 that has six indentations 223 at about 60 degrees apart on its outer diameter to engage with adapter 104 with three threaded holes 224 at about 120 degrees apart to accommodate three set screws. These set screws are aligned with the indentations on adapter sleeve 103 and can be tightened so that the front subassembly (shown later in FIG. 3) can be adjusted and secured to rear subassembly (FIG. 2) to sui, e.g., an airplane structure, and allow ease of handling for the mechanic so that the vacuum hose does not interfere with workpiece or other surrounding structure. The holes 225 at about 180 degrees are provided to loosen the adapter 104 from its sleeve adapter 103. Adapter housing 104 also has two pins 226, (about 180 degrees apart) pressed fit into the outer body diameter of adapter 104. These pins 226 are used to engage the vacuum sleeve 206 for vacuum purposes. Once the adapter 104 is secured to the motor 101 via adapter sleeve 103, the position of chuck key access hole 227 is such that chuck is exposed through hole 227 from where a chuck key is inserted to attach spindle 218 to chuck 202. There are two O-ring grooves 228 one on each side of hole 227 on the outer diameter of adapter 104.
Two O-rings 205 are mounted in to the grooves 228 for sealing purposes. The vacuum sleeve 206 has two right angled cutouts 229 on the edge of vacuum sleeve 206, about 180 degrees apart from each other and two U-shaped cutouts 230 also 180 degrees apart, on the circumference of the a vacuum sleeve. The positioning of U-shaped cutouts 230 in relation to L-shaped cutouts 229 is such that when vacuum sleeve is aligned with the pins 226 on adapter and turned to the locked position, chuck key access hole 227 is completely enclosed in vacuum sleeve 106 and the adapter 104 is fully sealed. The vacuum sleeve 206 can be fully seated over the adapter housing 104 in sealed condition. A two piece split type rear mounting bracket 136 is mounted on to the front of the adapter 104 using two screws. Two guide rods 138 are slid into two holes in bracket 136 with flat end 137 into holes and clamped with two set screws. These guide rods 136 provide guidance to the front subassembly (FIG. 3) assembled with the rear subassembly (FIG. 2) that helps the front assembly move in lateral direction without causing the subassemblies to rotate with respect to each other. This completes the rear subassembly as shown in FIG. 2.
Referring to FIG. 4, the front subassembly that is moveable in relation to rear subassembly, consists of a main body 212 on one side that faces the countersink tool, and accepts the radial bearing 213 in to the bore for sliding fit and bronze collar stop 214. The spindle is then inserted from the right side (as shown) through the collar stop 214, through the radial bearing 213, and through the main body 212 until it stops against the collar stop 214. At that time, the dowel pin 215 is aligned with the hole in stop collar 214 and the hole in spindle 218 and pressed into collar stop 214 and spindle 218 through the rectangular cutout 231 until it is flush with collar stop on the opposite side. The rectangular cutout 231 is provided for allowing the pin 215 to be inserted into the collar stop 214 and the spindle 218. Now the bronze bushing 211 is slid over the spindle 218 on the opposite end of the main body where the spindle is already protruding out through the main body 212. The spring 210 is slid over the bronze bushing 211. The bronze bushing 211 inside diameter is made to slide fit over the spindle 218 and outside diameter of bushing 211 is made to slide inside the spring 210. This bushing provides a support to the spring and guides it so the spring 210 does not buckle or bend during the countersink operation avoiding any interference between the any two wires of spring 210 and causing early failure of the device or subassembly. It also provides a bearing surface to spindle 218. Then a radial bearing 209 is inserted on the spindle 218 that is already protruding out of the main body 212, collar stop 208 is inserted on the spindle. The pin 207 is pressed into the hole through the U-shaped slots 232 of the main body 212, collar stop 208 and simultaneously through the hole in spindle 218 after aligning the holes in collar stop 208 and spindle 218. The positioning of U-shaped slots 232 are such that it provides space for pin 207 to be inserted, and all these components are mounted on the spindle 218 in to the bore of the main body 212. In this case, collar stop 208 may require some force to push the radial bearing 209 into the open end of the main body until the holes in collar stop 208 and spindle 218 are aligned. Three ball plungers 235 are screwed into three tapped hole into the main body 212 facing balls towards the rear side towards the motor 101 in such a way that all three balls 242 that are part of ball plungers 235 are in one plane perpendicular to the horizontal axis. The ball plungers 235 are adjusted to a preset tension. The countersink cutter 219 is screwed into the spindle 218 and secured firmly as shown in FIG. 4. The guide plate 216 is attached to the nose piece 217 using two dowel pins and with two screws for alignment. The ball plungers 235 that are adjusted to a preset tension in such a fashion, when subassembly of nose piece 217 and guide plate 216 is inserted into the main body 212 and turned, the nose piece 217 and guide plate 216 subassembly snap into a locked position.
The locking action can take place because there are three small holes 243 in the back side of guide plate 216. The three balls 242 snap into three holes 243 in the back side of guide plate 216. There is also a stop pin 244 in the back side of the guide plate 216. When the nose piece 217 and guide plate 216 subassembly are turned for locking action, stop pin 244 provides the subassembly with a stop to avoid over travel. The nose piece 217 has three minuscule slots 460 near the front end. When a vacuum is applied at the time of countersinking operation, fresh air is sucked through these minuscule slots 460 at high speed and it expands inside the walls of nose piece 217 near the cutting edges of the cutter 219. The cool air hits the cutting edges of the cutter 219 there by keeping the cutter cool during the cutting operation and extends the life of the cutter. The nose piece 217 has a welded tubular attachment 220 on the front side of the nose. This tubular attachment 220 acts as conduit for the dust or chips to be sucked out during the countersink operation. The open end of this tubular attachment 220 is attached to one end of vacuum hose 221 and the other end of vacuum hose 221 is attached to the exhaust end 245 of the motor 101. A breathable bag 159 is attached to the exhaust end 245 of the vacuum device on motor 101 for collection of dust or chips.
The speed control device 140 can be mounted into the front mounting bracket 139 such that the front part of the piston of speed control device 140 is slightly beyond the front surface 141 of the nose piece 217 so as to provide a preloading effect on the piston before actual countersink operation starts. The I.D ring 164 is slid on to the main body 212 and secured by nut 165 by screwing on the main body threads. This I.D. ring 164 identifies the size a complete assembly is designed for, for a particular fastener used for assembly purposes. Now this front subassembly (FIG. 4) consisting of main body 212 assembled with its components in it along with front mounting bracket 139, guide plate 216, nosepiece 217 with welded tubular attachment 220 and the vacuum hose 221 is ready to be installed in to the rear subassembly (FIG. 3) consisting of drill motor 101, adapter sleeve 103, adapter housing 104 with O-rings 205, and vacuum sleeve 206 along with rear mounting bracket 136 with guide rods 138.
The front subassembly (FIG. 4) can be installed in to the rear subassembly (FIG. 3) by inserting front subassembly main body 212 into adapter housing 104 and simultaneously the guide rods 138 inserted into holes provided in front mounting bracket 139 and also inserting the spindle 218 into the chuck 102. At this time, the gage 222 is inserted in the slot 246 of the adapter 206 and the rear subassembly (FIG. 2) and the front subassembly (FIG. 3) is pushed against the gage surface and held tight. The chuck 202 is tightened with the chuck key accessing through the hole 227 of adapter housing 104. Once the chuck 202 is tightened, the gage 222 is pulled out of the adapter 106 and stored away and the complete assembly is ready for countersink operation.
Countersink Cutter and Spindle Assembly
FIG. 5 shows the assembly of the countersink cutter 219 with spindle 218. The countersink cutter 219 can have a cutting edge 547 at about 100 degree or about 130 degree which is an angle type of fastener used in aerospace industry or any other angle desired, and also has a pilot 548. The cutter 219 can have an outer body diameter knurled 558 so as to make it convenient to engage and disengage the cutter with the spindle 18 simply by holding the cutter 219 tightly by hand and turning it clockwise or counterclockwise as needed. The cutter 219 can have a cylindrical body with an undercut 549 in such a location that the fluted area 550 merges into this undercut 549. This arrangement can allow composite dust or chips to flow through easily from fluted area to the undercut 549. The outer cylindrical body of the cutter 219 has a hole 551 to disengage the cutter 219, from the spindle 218 once it is assembled together.
The cutter shaft back end 565 can be flat and square in relation to the horizontal axis of the cutter 219. The surface 565 seats against the flat surface 563 in the bore of the spindle 218. When the cutter 219 with a square back end shaft surface 565 is assembled with spindle 218, the common contact surface 563 at the bottom of the bore of the spindle and 565 between the two becomes a reference surface for controlling the depth of countersunk hole. This common surface between 563 and 565 can provide the thrust in the direction of countersinking. The back end of cutter 219 can have a reduced cylindrical diameter 552 with another cylindrical groove 562 on the backend.
This groove is made to suit an O-ring 534 that when assembled with spindle 218 would keep the cutter tight inside the bore 553 of the spindle 218, and resist the tendency of becoming loose in the bore 553. The back end of the cutter 219 also can have a flat 554 that lets the cutter 219 pass past the spindle locking pin 533 on the side of the spindle 218. There is a partial grove or a flat 555 made on the back end where the locking action between the spindle 218 and the cutter 219 takes place. This condition provides the torque for the cutting operation. The spindle 218 has a counterbore 553 on the front end (the same bore diameter 553 depending) on the shaft design to accept the shaft end of the cutter 219. There is a locking pin 533 across the cylindrical body diameter that is offset from the center of the spindle 218. At the bottom of the cylindrical bore 553, a small hole 561 is provided so that when cutter 219 along with O-ring 534 seated in to the groove 562 of cutter 219 is mounted into the bore 553, the air trapped in the space in bore is pushed out at the bottom and also to help remove the cutter 219 out of the cylindrical bore 553 since the pressure at both ends of the back end shaft and the front outside the bore 553 is about the same.
There can be another hole 555 that intersects the small hole 561. Hole 551 may help remove the cutter 219 out the spindle 218 by placing a pin through it and turning the cutter 219 counterclockwise and sliding out of the spindle 218. The back end of the spindle 218 has three flats 564 with knurls on them placed at about 120 degree apart so that the chuck 102 jaws can grab on these flats 564. These knurls on the flats 564 provide resistance to avoid slippage between the jaws of the chuck 202 and flats 564 during the countersink operation. The back mounting cylindrical surface of the reduced diameter 552 of the cutter slips smoothly into the counterbore 553 of the spindle keeping the cutter symmetrical around the horizontal axis and concentric to the spindle 218 and the O-ring 534 provides slight interference between the bore 553 diameter of the spindle 218 and the O-ring 534.
Operational Technique
In use and application, a tool is designed to configure a predetermined hole profile in a machining operation to facilitate particular applications. The operator turns the motor on and aligns the pilot of the countersink cutter with the hole to be countersunk and inserts the power tool assembly and pushes the whole device until the main body bottoms out at the back end against the adapter where the gage has been used for setting up the tool. Once the tool has bottomed out, he removes the motor and works on the next hole. The hole can be countersunk to a desired depth that the tool has been set up for.
In one embodiment, a predetermined configuration hole profile can be prepared in a quick and efficient manner. The cutting or boring action of a drilling tool may be performed by the drilling tool, such as a combination of a tool holder and a drill insert attached thereto. Typically the cutter engages the material to be cut upon relative rotation between the tool and work piece.
Cutter Replacement in Assembly
The process of replacing the cutter 219 from the spindle 218 during the countersink operation involves holding the motor assembly in one hand, then first remove the hose 221 from the tubular attachment 220 of the nose piece 217 and using second hand the removal of subassembly of the guide plate 216 and the nose piece 217 by turning counterclockwise and sliding it out of the main body 212. The cutter 219 is exposed out of the front subassembly FIG. 3. A pin is inserted into the hole 555 of the spindle 218 holding it tight, and the cutter 219, while holding on the outer body, is turned counterclockwise and pulled out of the bore 553 of the spindle 218. If the cutter 219 cannot be turned by hand for removal purposes, another pin is inserted in hole 551 of the cutter 219, and turned counterclockwise while holding the pin inserted in hole 555 providing a torque to loosen the cutter and then pulled out of the bore 553 of the spindle 218. Once the cutter 219 is removed from spindle 218, a new cutter is slid in to the bore 553 of the spindle 218 past the pin 533 until it bottoms out at the top of spindle 218 and then turned clockwise until it stops. The cutter 219 is in locked position and the subassembly of the guide plate 216 and the nose piece 217 is locked into position by inserting into the main body 212 and turning counterclockwise until it stops against the stop pin 244 of the guide plate 16. The hose 221 is connected to the tubular end 220 of the nose piece 217. The motor assembly is ready to be used again for countersink operation.
This magnetic design can be more suitable for composite and other non-metallic materials. One embodiment is countersink process and method for replacing a cutter using an assembly tool process to replace cutter without any consequential result of corrective action after completion of countersink operation. In one embodiment, the process of countersinking includes creating a countersunk hole by using the device designed for this purpose. More particularly, this embodiment can make use of the concept that the travel of spindle can be controlled by preset gaged distance prior to the countersink operation. The front subassembly can travels back laterally against the fixed rear subassembly without any rotational bodies touching each other.
Other Embodiments
In one embodiment, the cutter is made such that the relative distance between the intersection of the longitudinal axis and the cutting edges, when projected on to the longitudinal axis and the squared back end of the countersink cutter, is maintained accurately so that when cutter is replaced the cutting edges always fall at the same location in the tool assembly.
In another embodiment, the cutter's shaft back end can be at 90 degrees with respect to the longitudinal axis and is perfectly squared. This surface can be used as a reference surface for maintaining the length of cutter from the intersection of projecting the cutting surface and horizontal axis and the back end of the shaft for replacement purposes. The cutter's outer body diameter also has a squared back end and when it is assembled it has a little clearance between the spindle and the back end of the cutter body diameter.
In another embodiment, the relative distance between the front face of the nose piece of the front part of assembly and the front surface of the spindle is always the same.
In another embodiment, the cutter can be positioned such that the intersection of pilot's outer diametrical surface and the cutting edge of the countersink is in line with the front surface of the nose piece of the front part of assembly, when the motor is at rest and is not in use and it has not been set for any depth of cut, i.e., the back end of the main body and the front end of the adapter mounted on the pistol grip motor, touch each other and indicate that the reading of the countersink gage would be at zero or it also indicates that cutter's intersection of pilot's outer diametrical surface and the cutting edge of the countersink is on the same plane with the front part of tool assembly.
In another embodiment there can be threads on the back end of cutter and the spindle as normally done on standard cutters.
In another embodiment, the knurling can be on the outer body diameter of the cutter so as to engage and disengage cutter by holding the cutter tight by hand and turning it clockwise and counterclockwise to achieve the desire effect.
In another embodiment, a gaging system sets up the depth of countersink by use of flat gage through the tool assembly and still getting the same results even when cutter is changed.
In another embodiment, the complete tool assembly with motor setup can be placed on work bench. There is less danger of getting the cutter damaged even during the idle times. This feature comes in very handy especially in the light of cutters that are manufactured with diamond blades bonded to it at the flutes since the diamond cutters are very expensive.
In another embodiment, the tool has small restrictions provided in front of the tool assembly where the cutting edges of the cutter are. At these restrictions, ambient air is sucked into the nose piece of the tool assembly. The sucking action of fresh air creates a void with strong negative pressure around these restrictions on the opposite sides of the walls where these restrictions are provided. The sucking action causes the ambient air to expand near the area of restrictions, That is the place where the cutting edges of the cutter are, where the expansion of air takes place. This expansion of air causes the temperature to drop in the vicinity of the cutter cutting edges during the chip formation action or dust formation action due to the grinding of cutting edges against the abrasive composite surface. So, the cutter remains cool during cutting action.
In another embodiment, the chip breaker feature is provided on all edges staggered from previous cutting edges except the last cutting edge of the cutter. The cutting edge finally sweeps the countersunk surface giving a fine finish to the conical surface of the hole.
In another embodiment, the engage and disengagement of cutter with spindle is made easier by providing the outer body diameter that has knurls on it for holding the cutter tight during assembly or disassembly.
In another embodiment, a vacuum at the nose piece can be included at the front part of the assembly. The pistol grip motor used has its own vacuum generating feature, but this is not enough when it is connected to tool assembly. Plenty of air is being sucked through the top part of tool assembly dissipating and leaking away through other areas of tool assembly and making the vacuum process ineffective. So in accordance with this embodiment, provision is made by sealing the openings at the top part of tool assembly by use of O-rings and a vacuum sleeve that seals the opening at the top part of tool assembly.
In another embodiment, the provision of two pins diametrically opposite to each other on top of adapter to engage the vacuum sleeve for vacuum purposes and sealing the assembly. “L” shaped cutouts are provided and are at a slight angle to let vacuum sleeve engage with pins tightly and keep the sleeve locked until it is removed when needed.
In another embodiment, a method of collection of debris, such as composite dust or metallic chips in to the breathable bags. An external plant vacuum or accessory vacuum hose can also be connected to this system to increase the effectiveness of the vacuum system in place of bagging system.
In another embodiment, a feed control for countersinking process is provided in the tool assembly by use of feed control device. This device takes over the operator's speed of countersinking process providing better countersunk surface quality and increases the life of cutter.
In another embodiment, the lateral movement of the front subassembly and the rear subassembly is guided by guide rods for smooth operation.
In another embodiment, window openings are provided in the adapter and main body of the tool assembly to access the roll pins for disassembly, if needed, that keep this device fastened together to each other.
In another embodiment, there is provided a tool assembly that mainly consists of two sub-assemblies—the front subassembly that moves along the longitudinal axis when the complete assembly is intact where as the rear subassembly that as stationary subassembly remains fastened to the drill motor held in hand when in use. The rear subassembly that is secured to the power drill motor mounted with a chuck or similar colleting device to secure spindle, a countersink bit attached to the spindle enclosed in a cylindrical part of the nose piece that has a vacuum tube welded to it, a vacuum hose—one end is attached to this exit end of the nose piece and the second end of the vacuum hose is attached to the exhaust end of the pistol grip motor.
In another embodiment, the rear subassembly part of the complete assembly consists of a pneumatically driven power drill motor, which has an adapter sleeve mounted on it using internal screw threads on adapter sleeve and outside diameter of this sleeve has six indentations 60 degree apart and at a fixed distance from the front edge to accommodate three set screws to secure an adapter housing for the assembly. The outside diameter of adapter sleeve is concentric with the drill motor threads to minimize any misalignment when an adapter is slipped on the outside diameter of adapter sleeve. The adapter housing inside diameter is made to slip fit on the adapter sleeve outside diameter. This adapter housing has three threaded holes 120 degrees apart on its outer diameter at exact distance from edge to align with three indentations on adapter sleeve and provided to secure adapter housing on the adapter sleeve. The six holes provided on adapter sleeve provide rotational position variations to the adapter housing so the operator can align the front subassembly with the rest of work piece and surroundings. This adapter housing also has another two holes offset from previous three threaded holes. These holes are provided to engage or disengage adapter housing from adapter sleeve. Along with above features of adapter housing, two grooves are provided on the outside diameter of housing some distance apart. In between these two grooves two large diameter holes 180 degree apart are provided perpendicular to the longitudinal axis. These holes are provided to accommodate a chuck key for tightening the spindle and two grooves are provided to accommodate two O-rings. These O-rings are furnished so that when a vacuum sleeve is slipped on the adapter housing over these O-rings, vacuum sleeve provides means for sealing this captured area between O-rings. Also another feature of this adapter housing is there is a provision of gage port so that a flat gage can be inserted through this for setting up the depth of countersink. The positioning of the two big opening in the adapter housing is such that chuck which is used for securing spindle is accessible through it so that a chuck key can be inserted for securing spindle.
In another embodiment, the adapter housing can have two small holes provided on the circumference of the outer diameter that accommodates two dowel pins located 180 degrees apart. These dowel pins are press fit in to these holes. The purpose of the dowel pins is to engage and disengage the vacuum sleeve when it is slipped on the adapter housing. After engaging these pins with two right angled cut outs 180 degrees apart made on the vacuum sleeve, the vacuum sleeve can then be locked to the adapter housing by turning the vacuum sleeve until it stops. The positions of the tracks or right angled cutouts on vacuum sleeve are in such a relation with the two dowel pins, that when sleeve is locked on the adapter housing, the two big openings for chuck key are enclosed totally inside the vacuum sleeve between two O-rings. This creates a completely sealed area to make vacuum action effective. Another feature of vacuum sleeve is that it has two u-shaped long slotted cutouts on its body in such a relationship with right angled cutout for dowel pins that when it is in disengagement position from adapter housing, the two opening for chuck insertion are exposed so that chuck key can be used to disengage the spindle for adjustment purposes. The u-shaped design also has another advantage that it provides access for the gage to be inserted in to the gage port for setting up the complete assembly for countersink process. The gage port that is provided on the sleeve housing is aligned with the u-shaped opening in the vacuum sleeve and gage is inserted to make the complete setup ready for operation. While the countersink operation goes on and when the vacuum sleeve is in locked position, the gage port is then covered under the vacuum sleeve where there in no u-shaped opening. This prevents the dust or debris to get into gage port and keeps it clean. Another feature of this embodiment is that a provision is made so that the back end of the gage port surface facing towards the motor provides the stop surface for the main body indicating completion of countersink depth desired. When no gage is inserted into the gage port and the back end of the main body touches the surface of the adapter house, this indicates zero setting of the cutter. The adapter housing also has a hole through its body in the center in longitudinal direction to accept the spindle.
In another embodiment, the adapter housing can have an inside diameter at the front of the adapter housing that provides the guidance to the front subassembly during the assembly of front subassembly to the rear subassembly. It is aligned so that rear subassembly provides the front subassembly the freedom to slide in and out of the rear subassembly during the countersink operation.
In another embodiment, the means for attaching the front subassembly to the rear subassembly include the drill motor comprises a main body that has back end such that it slides into the front end of the adapter housing of the rear subassembly. The back end of the main body also has four slotted openings. The purpose of these openings is to provide access to the roll pin that is pressed tightly into the diameter of the spindle crosswise to hold other components inside the main body, such as bronze bushings, radial bearing, spring etc. The access is provided so that front subassembly can be dismantled conveniently using a small hand punch manually. Another feature is the provision of a compression spring that helps bring the front assembly to the original position. Another feature of the main body is that it has three alignment lobes built on it. These provide the means for alignment with the nose piece that is detachable from the front subassembly for the purpose of replacement of cutter. Another advantage of these lobes is that these provide room for installation of three ball plungers. These ball plungers are the means for securing the nose piece to the main body via a guide plate in between. The lobes are the integral part of the main body but can be made as a separate part slip fitted on to the main body and held with set screws. This may provide a means to cut manufacturing cost. Another feature of the main body is the positioning of three lobes that provided only one way for insertion of main body into the nose piece via guide plate causing no confusion to operator as to how to locate lobes in relation to lobe opening provided in the guide plate. The front part of the main body has four longitudinal slots that provide access to the roll pin that holds the shaft assembly together along with bearing inside the main body and bronze bushing. The front end of the main body also has a precision bore to accommodate a radial bearing that supports the spindle in the front assembly. The feature is depicted as a complete front sub assembly is held together by these two roll pins that are provided on two ends of the spindle. In between the two roll pins are bushings and bearings and spring. The radial bearings provided on both ends of the main body provide smooth rotational movement of spindle, remove misalignments in the front sub assembly and provided radial support; bronze bushings provide support to radial bearings and smooth operation of spindle.
In another embodiment, the main body can have an identification band that is slipped on to outside diameter and then secured with a identification band retainer. This identification band provides the means of identifying what size fastener the setup is made for. Different colors are used to depict various sizes of holes diameter setup.
In another embodiment, the front subassembly is that a guide plate with special designed openings is provided to accommodate the lobes of the main body. The guide plate allows the alignment between the two parts and there is provided a stop pin on the underside of the guide plate. This stop pin acts as a stop to prevent the main body for over traveling inside the nose piece when main body is engaged with nose piece. One more feature provided in the guide plate is that it has three small diameter holes for the ball plungers to rest when main body is secured to the nose piece. There, also are two male dowel pins pressed in the underside of the guide plate so that guide plate can be aligned with the nose piece and then secured with flat head screws.
In another embodiment, the front subassembly also comprises of the nose piece as has been mentioned earlier. This nose piece has its own tubular weldments welded to the side for debris to be evacuated before it gets into the rest of mechanism. This tubular weldment is connected to one end of vacuum hose to carry all the debris out to a means of collection of debris, such as breathable bag. The second end is then connected to the exhaust end of the motor where debris collection bag is attached. The nose piece has another feature at the front end that it is provided with three minuscule sized slots-near the front end where the cutting edges are when cutter is in place. These slots act as cooling devices. When vacuum is applied during the cutting action, fresh air at ambient temperature is sucked in from these tiny slots. Air expands inside the walls of nose piece in and along the cutting edges of the cutter this expansion of air drops the temperature of the cutter when air hits on the cutting edges. This keeps the cutter cool and extends the life of cutter several times comparing to action where the situation when there is no cooling.
In another embodiment, the nose piece has is that there is provision for cutout in the front of nosepiece so that the operator can see the countersink bit, otherwise the outside diameter of the nose piece would block the sight and would not be easily able to insert the cutter tip in to the existing hole. This nose piece also has a bore drilled in to it to precisely accommodate the main body front end.
In another embodiment, the front part of subassembly is that a spindle and the cutter have a quick change mechanism for securing purposes. The spindle has a precision bore so that the cutter precision ground shaft diameter can slip into the bore providing the alignment between the spindle and the cutter with minimal radial play allowed depending upon the standard manufacturing practices. The spindle has a cross mounted pin inside slightly offset from the center of the spindle, so that the cutter can be inserted through one end past the pin and the cutter also has a flat at the shaft end to get past the pin. The cutter also has another feature, ground flats besides the previously mentioned flat on the shaft that can trap the pin in the spindle when the cutter is turned about thirty degrees. The tolerances are so close that there is no lateral play or radial play, there by securing the cutter in the spindle. The pin acts a driving member of the spindle when it trapped in between flats of the cutter. Another feature that is provided on the shaft end is that it has a groove to accommodate an O-ring on it. This O-ring on the shaft end, when it is inserted into the spindle bore, it keeps the cutter in place without any fear of losing the cutter if the motor is turned counterclockwise or otherwise cutter may slide out of spindle. Unless the operator decides to take out the cutter it would not come out because of sufficient resistance O-ring provides between the cutter and the spindle.
In another embodiment, there are two brackets mounted on the complete assembly, one bracket is secured to the main body of the front subassembly and the other bracket is secured to the fixed end of rear subassembly using socket head cap screws. These brackets are then mounted with two guide rods that are secured on the rear bracket on one end using set screws and slide back and forth on the other ends of guide rods in precision holes provided in the front bracket. These guide rods provide stability to the whole setup and allows smooth sliding operation even though the main body has its own feature that slides inside the adapter housing. The front bracket also has another feature to accommodate a speed control and shock absorber device mounted of the front end. This device provides support and resistance that is adjustable on it, to the operator when he pushes the motor against the airplane structure or panel to countersink holes. The operator can adjust this resistance so it is not over bearing yet not be able to plunge the countersink tool in to the panel causing the damage to it. Speed control device may also include a pressure control knob that may be rotated to control the tension setting of surge control device, or in other words, to control the axial force required to move plunger relative to hydraulic cylinder. Increasing the tension setting of surge control device provides greater resistance against an axial force applied to countersink, and thus decreases the axial speed, or feed, at which countersink tool may travel during countersink operation. Likewise, decreasing the tension setting provides less resistance and increases the axial speed at which countersink may travel. The surge control tension setting may be selected based on one or more criteria, such as for example, the material properties and dimensions of the workpiece, the material properties and dimensions of countersink tool. It should be understood that surge control device may include additional hydraulic dampers or any other suitable means of controlling the axial speed, or feed, of cutting tool, such as, for example, springs or compressible materials.
In another embodiment, several component parts are designed in such a way these can be manufactured very economically or some even purchased of the shelf to make a complete assembly. The countersink cutter is specially made from materials that would be more suitable for application where it is going to be used on, for example, for composite material to be cut, the countersink material used on cutting edges is fine grade diamond blades, and for tough materials, the cutter is made from tungsten or molybdenum carbide. This carbide cutter can also be used on aluminum materials. Even high speed steel can be used for cutter for aluminum applications. But the most important part of the cutter is that it must be made extremely accurate with tight tolerances to achieve the correct results and make the power tool countersink assembly error proof.
From one perspective, a basic principle of setting up the tooling with a flat gage between the front and the rear assemblies and method of engaging and disengaging the front nose piece with main body can be utilized also right angle motors, in stationary machine tools to achieve the depth control of the drilling or countersinking operation or similar operation where a rotary cutting tool with a pilot or without a pilot is utilized. The cutter shaft design feature can also be made acceptable to other rotary tools such as drill and countersink combination tools, drills, counterbores etc. It is understood that the tool can also be used in other industries beside aerospace industry where accurate and controlled depth of countersink is needed.
The above detailed description of the embodiments, and the examples, are for illustrative purposes only and are not intended to limit the scope and spirit of the invention, and its equivalents, as defined by the appended claims. One skilled in the art will recognize that many variations can be made to the invention disclosed in this specification without departing from the scope and spirit of the invention.

## Claims

1. A countersink assembly adapted to be attached to a drill motor for drilling and countersinking a hole in a workpiece, comprising: an approximately cylindrical rear subassembly extending between a first end and a second opposed end and having a slot for a gage, wherein the outer diameter of the assembly defines an approximate first cylinder, the rear subassembly is mounted to a drill motor with an adaptor sleeve; an approximate first cylindrical body has a through hole for providing access to a chuck for tightening purposes and has two O-ring grooves where two O-rings are mounted on; said rear subassembly also comprises of a cylindrical vacuum sleeve that slides over the first cylindrical body with the O-rings mounted on it; an approximate cylinder front assembly having a main body, a coaxial spindle with a spindle shaft, wherein the front subassembly moves laterally in relation to said rear subassembly; the front subassembly also comprises of a spring with a bushing inside it entrapped in said main body; having quick change mechanism for removal of a nosepiece subassembly; and said nosepiece connected to countersink assembly vacuum system of a motor or connected to external source; an approximately cylindrical countersink cutter, operably connected to said drill motor, said coaxial spindle having a pin (533) inserted in a bore to accommodate a cutter shaft using a quick change mechanism to engage, having a body diameter with knurls and a hole (551) through, a pilot (548) and a set of cutting edges, wherein said rear subassembly is stationary; said coaxial spindle shaft mounts into said drill motor; said cutter shaft has a flat front end surface or edge (556) and a flat back end (565) along a longitudinal axis, an angular flat surface, and has a groove (562) to accommodate an O-ring (534); said front end surface or edge (556) of said cutter shaft coincides with a back end of said body diameter (558) of said cutter; said body diameter (558) has said knurls on a cylindrical body diameter surface; an angular flat surface locks into said pin of said coaxial spindle; and an intersection point (566) of the longitudinal axis and said cutting edges, when projected on to the longitudinal axis, is held in alignment at a substantially constant distance from the back end (565) surface of said cutter; and the distance between a front surface (557) of said coaxial spindle and the front surface (141) of said nose piece is constant and is equal to the distance between said front end surface or edge (556) of body diameter (558) flat surface and the center (567) of the radius when drawn between the tangent of said pilot diameter and said cutting edges;
a subassembly consisting of a rear bracket (136) mounted on said stationary first cylindrical body, connected with an alignment rod (138) with screws to a front bracket (139) mounted on said main body; a speed controller (140) adjusted to be used as a stop mounted on said front bracket facing towards said rear bracket, said gage is used between said speed controller and said rear bracket for setting up the depth.

2. The assembly as claimed in claim 1, wherein the back surface (565) of said cutter bottoms out at the bottom (563) of said coaxial spindle bore when assembled.

3. The assembly as claimed in claim 1, further comprising of an O-ring (534) on said cutter shaft; when assembled into said bore (553) of said coaxial spindle, provides resistance between said cutter shaft and said coaxial spindle bore and helps said cutter remain in place and concentric with said coaxial spindle.

4. The assembly as claimed in claim 1, further comprising outside major diameter (558) having said knurls and said hole (551) through said body diameter of said cutter that engages said coaxial spindle.

5. The assembly as claimed in claim 1, wherein said angular flat on said cutter shaft and said pin are inserted at an offset position from center through said bore of said coaxial spindle and engage each other to create a quick change mechanism for said cutter to be mounted and removed from said coaxial spindle and provide torque to said cutter.

6. The assembly as claimed in claim 1, wherein said coaxial spindle has said bore to be able to accommodate said cutter shaft end with minimum play between said cutter shaft and said coaxial spindle bore.

7. The assembly as claimed in claim 1, wherein said coaxial spindle has said bore to be able accommodate said O-ring mounted on said cutter shaft.

8. The coaxial spindle as claimed in claim 1, wherein said coaxial spindle shaft has one or more flats with serrations or said knurls to provide slip resistance when external forces are applied during countersink operation.

9. The assembly as claimed in claim 1, wherein said front subassembly has a quick change mechanism to allow for the removal and assembling of said nose piece subassembly; and to allow for the exposure of the cutter for replacement purposes.

10. The assembly as claimed in claim 1, wherein the main body has multiple lobes (234) at equally spaced number of degrees apart and has at least same number of ball-plungers mounted in as many number of lobes, preset to a correct tension to allow for quick engagement and disengagement from said nosepiece mounted with a guide plate with cutouts, one less number of cutout compared to number of lobes in said main body, and a v-shaped opening (235) for viewing said cutter pilot and to maintain concentricity between the front and back subassemblies guided by diameter (233) of the main body (212) where the cutouts are present.

11. The cutter assembly as claimed in claim 1, wherein said nose piece has several minuscule openings such as holes or slots (460) to make vacuum action more effective and keep said cutter cool when the air expands at the entrance dropping air temperature substantially and cooling said cutting edges entrapped inside said nosepiece and workpiece space.

12. The assembly as claimed in claim 1, wherein the main body has multiple lobes that pass through cutouts, one less number of cutouts in said guide plate, compared to number of lobes, and a v-shaped opening in said subassembly of said guide plate and said nose piece that acts as a guide for lobes on said main body; and said nosepiece is turned circumferentially for locking purposes, such that all ball plungers snap into corresponding holes on the back side of said guide plate and said main body stops from further movement and locks itself with said nose piece.

13. The assembly as claimed in claim 1, wherein said gage is inserted through said slot in rear subassembly touching the surface of adapter housing (104); and said front subassembly slides towards said rear subassembly until said main body as part of said front subassembly touches said gage; and said coaxial spindle shaft, that is a part of said front subassembly, is secured into chuck with the aid of chuck key, and said bushing (211) length is adjusted to avoid over travel.

14. The assembly as claimed in claim 1, wherein said speed controller is used as a stop and is mounted on said front bracket, facing backwards toward said rear bracket where said gage is used between said speed controller and said rear bracket to set a gage depth.

15. An approximately cylindrical cutter operatively connectable to a coaxial spindle and a drill motor, compromising: a set of cutting edges and a cutter shaft, wherein said cutter shaft has a flat front end surface or edge (556) and a flat back end (565) along a longitudinal axis, an angular flat surface, and a groove (562) that accommodates an O-ring (534); said front end of the shaft coincides with the back end of the body diameter (558) of said cutter; said angular flat surface locks into a pin of said coaxial spindle; and an intersection point (566) of the longitudinal axis and said cutting edges, when projected on to the longitudinal axis, is held at a constant distance from said back end (565) surface of said cutter; and said cutter is operatively connected to said spindle and said drill motor through said coaxial spindle shaft; wherein the distance between a front surface (557) of said coaxial spindle and a front surface (141) of a nose piece is held constant and is equal to the distance between said front end flat surface or edge (556) of said body diameter (558) and a center point (567) of the radius when drawn between the tangent of said pilot diameter and said cutting edges of said cutter; and an intersection point (566) of the longitudinal axis and said cutting edges, when projected on to the longitudinal axis, is held at a constant distance from said back end (565) surface of the cutter and is equal to the distance from the surface (563) of said coaxial spindle bore and said front surface (141) of said nose piece and adding the distance between said intersection point (566) and said center point (567) along the axis.

16. The cutter as claimed in claim 15, wherein said coaxial spindle shaft has one or multiple flats with serrations or knurls to provide slip resistance when external forces are applied during countersink operation.

17. The cutter as claimed in claim 15, wherein the cutter has number of flutes for said cutting edges for chips to flow through, in such a fashion that all flutes merge into a circular annular opening space (568) in the back which facilitates collection of dust or chips to be vacuumed through said nosepiece, thereby keeping the complete assembly of countersink tool free of debris.