Workpiece removal device for a hole saw

A workpiece removal device 10 for a hole saw 8 includes a positioning member 12 joined to the hole saw 8, a first securing member 14 joined to the positioning member 12, a biasing member 16 having a first end 18 joined to the first securing member 14; a second securing member 20 joined to a second end 22 of the biasing member 16; and disposing the second securing member 20 in communication with a workpiece whereby a preselected portion of the workpiece is ultimately severed from the workpiece by the hole saw, whereupon, the biasing member forcibly removes the severed preselected portion of the workpiece from the hole saw.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to hole saws and more particularly, to a workpiece removal device for a hole saw.

2. Background of the Prior Art

Hole saws are commonly used to cut out annular portions from a workpiece. The workpiece may include wood, drywall, plaster and cylinder blocks. The annular cut out portion may be utilized for piping, electrical conduit or access portals to wiring and control equipment. The hole saw includes a drill bit that penetrates a workpiece to stabilize the hole saw assembly, including a rotary drive tool, as a cutting portion of the hole saw engages the workpiece. The cutting portion ultimately severs a predetermined portion of the workpiece thereby providing an aperture after the cutting portion and the severed portion “stuck” in an internal cavity of the hole saw, is extracted from the workpiece.

The problem with prior art hole saws is that the severed portion inside the hole saw can be difficult to remove. In some instances, a person needs to forcibly pry the severed portion from the hole saw with a screwdriver or similar rigid tool. Whatever the technique utilized to remove the severed portion, an excessive loss of time and money result from the user having to wrestle with the manual removal of the severed portion from the hole saw cavity.

A need exists for a device that can “eject” the severed portion from the hole saw without requiring manual assistance.

SUMMARY OF THE INVENTION

It is an object of the present invention to overcome many of the disadvantages associated with hole saws.

A principle object of the present invention is to provide a workpiece removal device for a hole saw. A feature of the device is that it is detachably secured to the hole saw. An advantage of the device is that larger or smaller sized devices may be utilized with a particular hole saw to enable the hole saw to cut a myriad of workpiece materials with varying thicknesses.

Another object of the present invention is to provide a workpiece removal device that removes a severed portion of the workpiece from a cavity in the hole saw. A feature of the device is a biasing spring that has a secured first end and a “free” second end that promotes axial movement of the spring relative to a drill portion of the device. An advantage of the device is that the spring forcibly removes the severed workpiece portion from the hole saw without manual assistance.

Yet another object of the present invention is to direct a spring biasing force perpendicular to a preselected portion of a workpiece. A feature of the device is the integral joining of the first and second securing members with corresponding ends of the biasing spring, the securing members each having an aperture through a central portion thereby forming a “spool” configuration when opposing ends of the biasing spring are joined to the securing members. An advantage of the device is that the relative position of the spring can be maintained while the spring is compressed during the cutting of the predetermined portion of the workpiece. Another advantage of the device is that the relative position of the spring can be maintained when the spring expands and forcibly removes the cut portion of the workpiece from the internal cavity of the hole saw.

Another object of the present invention is to maintain the assembled spring and securing members upon the drill bit. A feature of the device is a drill bit having a longitudinal dimension greater than the axial dimension of the spring and securing members. An advantage of the device is that the spring and securing members do not have to be axially realigned with the drill bit after the severed portion of the workpiece has been removed from the hole saw. Another advantage of the device is that the spring does not engage the drill bit during operation of the hole saw.

Still another object of the present invention is to stabilize the device, drill bit and the cutting portion of the hole saw. A feature of the device is a threaded portion of the drill bit that removably receives a locking nut which ultimately secures the drill bit to the hole saw. Another feature of the device is a longitudinal dimension that disposes a second securing member upon the drill bit such that the second securing member and a cutting portion of the hole saw engage a workpiece substantially simultaneously. Another feature of the device is a drill bit having a substantially longer axial dimension than the axial dimensions of either the biasing spring or hole saw. An advantage of the device is that the axial positions of the drill bit, hole saw and biasing spring relative to the workpiece are substantially maintained during the cutting operation thereby providing an aperture with axis perpendicular to the surface of the workpiece. Another advantage of the device is that the drill bit axially guides the hole saw into engagement with the workpiece.

Another object of the present invention is to provide a replaceable drill bit. A feature of the device is a set screw that ultimately engages a stem portion of the drill bit via an aperture in a locking member. Another feature of the device is a drill bit with a threaded stem portion that is inserted into a threaded recess in the locking member. An advantage of the device is that drill bits of varying diameters may be utilized to engage the workpiece. Another advantage of the device is that the drill bit may be replaced after becoming “dull” due to excessive use.

Another object of the present invention is to provide a replaceable biasing spring. A feature of the device are first and second securing members that are joined to the biasing spring, but that are allowed to slide upon the surface of the drill bit via central orifices. An advantage of the device is that the biasing spring need only be replaced rather than the entire hole saw assembly when workpieces of varying fabrication materials are cut. Another advantage of the device is that the biasing spring is easily replaced after becoming fatigued due to excessive use.

Another object of the present invention is to provide a device that prevents friction between a second securing member and a workpiece. A feature of the device are multiple ball bearing that are disposed between inner and outer raceways of the second securing member. An advantage of the device is that the outer raceway remains stationary upon engaging the surface of the workpiece thereby avoiding excessive heat generation that could damage the device when the hole saw penetrates a workpiece.

Another object of the present invention is to provide a device that maintains a cut portion of a workpiece within a cavity in the hole saw. A feature of the device is a hole saw having an axial dimension slight shorter than the axial dimension of a drill bit, and relatively longer than the axial dimension of the combined biasing spring and securing members. An advantage of the device is that a severed portion of the workpiece remains partially in the hole saw after removing the hole saw from the workpiece thereby preventing the severed portion from slipping off the drill bit and remaining inside the workpiece.

Briefly, the invention provides a workpiece removal device for a hole saw comprising a positioning member joined to the hole saw; a first securing member integrally joined to said positioning member; a biasing member having a first end integrally joined to said first securing member; a second securing member integrally joined to a second end of said biasing member; and means for disposing a predetermined portion of said second securing member in communication with a workpiece whereby a preselected portion of the workpiece is ultimately severed from the workpiece by the hole saw, whereupon, said biasing means forcibly removes the severed preselected portion of the workpiece from the hole saw.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now toFIGS. 1,2and3, a workpiece removal device for a hole saw8(not part of the invention) is denoted by numeral10. The device10is fabricated from metal with carbon steel being the material of choice. The device10includes a positioning member12that is detachably joined to the hole saw8, a first securing member14integrally joined (via welding or similar methods) to the positioning member12, a biasing member or spring16having a first end18integrally joined to the first securing member14, and a second securing member20integrally joined to a second end22of the spring16. An outer wall24of the second securing member20is ultimately disposed to communicate (irrespective of the orientation of the hole saw8) with a preselected portion of the workpiece to promote the severance of the preselected portion from the workpiece by the hole saw8. As the hole saw8cuts deeper into the workpiece, the spring16is increasingly compressed until the hole saw8severs the preselected portion, whereupon, the spring16expands to forcibly remove the severed preselected portion of the workpiece from the hole saw8.

The positioning member12includes a drill bit26integrally joined to a locking member28with a threaded end portion30. The threaded end portion30of the locking member28is integrally joined to a shank portion32. The locking member28is configured to snugly insert through an aperture34in the hole saw8whereby the position of the positioning member12is secured relative to the hole saw8upon the threaded joining of a locking nut36to the threaded end portion30. The shank portion32is removably secured to a rotary motion tool (not depicted) thereby providing rotational force to the drill bit26. The drill bit26has a typical configuration and is dimensioned to penetrate, when rotated, the workpiece sufficiently to guide and stabilize the second securing member20and hole saw8upon engaging the workpiece thereby promoting the severing of a preselected portion66of the workpiece until the hole saw8is removed from the workpiece.

The locking member28is substantially a standard threaded hex nut with the exception that the external wall configuration has been modified to include two opposing planar walls38and two opposing arcuate walls40that snugly insert through a corresponding configuration of the aperture34in the hole saw8thereby promoting the transfer of rotary motion from the positioning member12to the hole saw8while reducing wear between engaging portions of the locking member28and the hole saw8when the forceful transfer of rotary motion occurs. The threaded end portion30is integrally joined to the locking member28via welding or similar methods. The threaded end portion30includes typical NPT type outer threads having an outer diameter that facilitates the relatively snug passage of the end portion30through the aperture34in the hole saw8. The end portion30and the locking member28are ultimately inserted through the aperture34until an outer planar wall42of the first securing member14engages an inner planar wall44of the hole saw8.

The shank portion32of the positioning member12has a typical hexagonal configuration for insertion into a standard chuck portion of a rotary drive tool. The shank portion32is dimensioned to cooperate with the longitudinal and diameter dimensions of the threaded end portion30to allow the locking nut36to snugly slide upon the shank portion32until the internal threads45of the locking nut36engage the outer threads of the end portion30, whereupon, the locking nut36is tightened until forcibly engaging an outer planar wall46of the hole saw8. The tightened locking nut36results with the threaded end portion30extending longitudinally through the nut36to dispose the shank portion32for insertion into the chuck portion of the rotary drive tool. The shank portion32has a longitudinal dimension that facilitates a slight separation between the threaded end portion30and the chuck portion of the rotary drive tool after an end wall48of the shank portion32engages a corresponding inner wall of the chuck portion.

The locking nut36has an internal configuration that includes a cavity50that snugly captures the locking member28protruding through the hole saw8as the threaded end portion30engages the internal threads45of the nut36. The cavity50includes a conical reducing portion51that joins with the internal threads45to “funnel” the end portion30into threaded engagement with the internal threads45. The configuration of the locking nut36promotes the threaded joining of the locking nut36with the end portion30such that an inner end wall52of the nut36forcibly engages the outer planar wall46of the hole saw8thereby rigidly securing the positioning member12to the hole saw8.

The first and second securing members14and20include standard washers having central apertures54that snugly receive cooperating portions of the positioning member12therethrough. The diameters of the securing members14and20are relatively larger than the diameter of the spring16to facilitate a stable joining of the securing members14and20with the spring16. The spring16is fabricated from metal and has sufficient expansion force, after being compressed, to forcibly remove a severed portion of a workpiece from an internal cavity56of a hole saw8. A suitable spring16is manufactured by Prime-Line Products Company in San Bernardino, Calif. The part number of the spring16is SP-9709.

In operation, a hole saw8is selected to circularly cut a predetermined portion of a workpiece. Based upon the size of the predetermined portion and the fabrication material for the workpiece, a device10is selected to guide the hole saw to ultimately engage and cut the workpiece, and to remove the cut portion of the workpiece from the internal cavity56of the hole saw8after the predetermined portion66has been completely severed from the workpiece. The device10is assembled and secured to the hole saw8by inserting a shank portion32of a positioning member12of the device10through an aperture34in a central portion of the hole saw8such that an outer wall42of a first securing member14engages an inner wall44of the hole saw8, whereupon, a locking nut36is threaded onto a threaded end portion30of a locking member28. The locking nut36is tightened upon the threaded end portion30until the inner end wall52of the nut36forcibly engages an outer wall46of the hole saw8thereby rigidly securing the device10to the hole saw8.

The outer wall42of the first securing member14is integrally joined to an outer wall58(seeFIG. 1B) of the locking member28; a spring16having already been secured to inner walls60and62of first and second members14and20thereby securing and axially aligning the spring16and securing members14and20to a drill bit26which is integrally joined to a central portion of the securing member28. The securing members14and20, and the spring16are configured to allow the securing members14and20to snugly slide upon the periphery of the drill bit26, while the spring16is suspended circumferentially about the bit26and between the securing members14and20such that the spring16does not engage the bit26at any time, irrespective of a compressed or extended disposition as depicted inFIGS. 2 and 3.

After securing the device10to the hole saw8, the shank portion32is removably inserted into a rotary power tool. A tip portion64of the drill bit26is centrally positioned upon the predetermined portion of the workpiece that is to be cut by the hole saw8. The rotary power tool is then energized to forcibly drive the drill bit26into the workpiece until the hole saw8engages the predetermined portion of the workpiece to be cut and removed. The drill bit26and the hole saw8both continue to penetrate until the hole saw8completely severs the predetermined portion from the workpiece resulting in the compression of the spring16and the disposition of a severed workpiece portion66into the internal cavity56of the hole saw8as depicted inFIG. 4. The hole saw8is then manually separated from the workpiece resulting in the spring16expanding to forcibly remove the severed workpiece portion66from the internal cavity56of the hole saw8as depicted inFIG. 5, whereupon, the severed portion of the workpiece is manually slid from the drill bit26thereby allowing the hole saw to cut another annular opening into the workpiece.

Referring now toFIGS. 1A and 1B, exploded perspective views of modifications of the device ofFIG. 1in accordance with the present invention are depicted. The modification of figure IA is the uncoupling of the second member20from the second end22of the spring16. The second member20is allowed to “float” upon the spring16thereby transferring significant friction and heat from the contacting surfaces of the second member20and the workpiece to contacting portions of the second member20and the spring16. The first end18of the spring16remains joined to the inner wall60of the first member14for the device10ofFIGS. 1 and 1A.

The modification ofFIG. 1Bis the uncoupling of the second member20from the second end22of the spring16, and the uncoupling of the first member14from the locking member28. The first end18of the spring16remains joined to the inner wall60of the first member14. The modification ofFIG. 1Btransfers significant friction and heat from the contacting surfaces of the second member20and the workpiece (FIG. 1) to contacting portions of the second member20and the spring16, and contacting portions of the first member14and the locking member28. The modification ofFIG. 1Bdistributes the friction and heat between the workpiece, the spring16, the first and second securing members14and20, and the locking member28thereby reducing the possibility of damaging any component of the device10.

Referring now toFIG. 6, an exploded perspective view of an alternative design for the device ofFIG. 1in accordance with the present invention is depicted. The alternative design ofFIG. 6is the replaceability of the drill bit26. The drill bit26inserts into a recess that is aligned with the orifice54of the first member14. The position of the drill bit26is secured via a set screw70inserted into a threaded orifice72in a planar wall38of the locking member28. The threaded orifice72intersects the recess that receives the drill bit26. The set screw70is tightened until it engages a stem or shank portion73of the drill bit26. Should the drill bit26become dulled or otherwise not effective, or should an alternative bit26be required, the inserted drill bit26is easily replaced by loosening the set screw70.

Referring now toFIG. 7, an exploded perspective view of another alternative design for the device ofFIG. 1in accordance with the present invention is depicted. The alternative design ofFIG. 7includes the uncoupling of the first member14from the locking member28, and the integral joining of a washer74to the inner wall44of the hole saw8. The alternative design ofFIG. 7allows the integrally joined biasing spring16and securing members14and20, to “ride” upon the washer74via the outer wall42of the first member14. This design permits the spring16and securing members14and20to be quickly replaced when a fatigued spring16or an alternative spring16is required. Further, the design transfers friction from the second member20depicted inFIG. 1to both the first and second members14and20depicted inFIG. 7thereby increasing the longevity of all components.

Referring now toFIG. 8, an exploded perspective view of another alternative design for the device ofFIG. 1in accordance with the present invention is depicted. The alternative design ofFIG. 8replaces the second securing member20with a bearing assembly76that includes an inner raceway78, an outer raceway80and a plurality of frictionless ball bearings82sandwiched therebetween in annular channels84such that inner planar walls86of the raceways78and80remain separated. The raceways78and80are cooperatively held together via a securing member88that includes a hub portion90which is forcibly inserted through apertures92in the raceways78and80thereby capturing the raceways and the bearings82therein. The hub portion90includes and orifice91that facilitates the insertion of the drill bit26through the bearing assembly76, spring16, first securing member14and into the locking member28.

The raceways78and80are permanently sealed with greased bearings82therein to negate the systematic lubrication of the bearings82. Instead of utilizing sealed bearings, a standard bearing configuration with a grease zerk for routine lubrication may be used. The first end18of the spring16is integrally joined to the inner wall60of the first securing member14. The second end22of the spring16is integrally joined to an outer wall94of the inner raceway78. In operation, an outer wall96of the outer raceway80engages the surface of a workpiece. Upon energizing a rotary drive tool, the device10rotates except for the outer raceway80which maintains its position relative the workpiece thereby preventing friction and heat generation between the device and the workpiece.

Referring now toFIG. 9, an exploded perspective view of an alternative design for the device ofFIG. 6in accordance with the present invention is depicted. The alternative design ofFIG. 9uses a drill bit26with a threaded stem or shank portion100that is screwed into a cooperatively threaded receiving recess (not pictured) in the locking member28. The receiving recess is axially aligned and cooperatively configured with the central aperture54in the first securing member14to promote the snug insertion of the shank portion100into the receiving recess. The design ofFIG. 9deletes the set screw70ofFIG. 6thereby reducing the number of components required to secure the drill bit26to the locking member28.

Referring now toFIG. 10, a perspective view of a hole saw104with a drill bit106protruding therefrom is depicted in accordance with the present invention. The hole saw104(now part of the invention) includes a slightly tapered configuration and relatively longer axial dimension than the hole saw8above. The tapered configuration provides a cutting edge108that is relatively smaller in diameter than the bottom wall110of the saw104. The longer axial dimension results in more of the severed portion66being contained inside the hole saw104after the spring16of the device10has expanded to a non-biased position. A larger portion of the severed portion66being contained inside the saw104, “assists” the drill bit106in retaining the severed workpiece portion66upon the bit106as the hole saw104is removed from the workpiece thereby preventing the severed portion66from falling from the bit106and obstructing the newly cut hole. The tapered configuration promotes the quick manual removal of the severed preselected portion66from the hole saw104by decreasing the surface area of engagement between a conically configured inner wall112of the hole saw104and the cylindrically configured outer wall of the severed portion66.

Referring now toFIG. 11, an exploded perspective view of a modification of the device ofFIG. 6in accordance with the present invention is depicted. The device ofFIG. 11includes a drill bit26having an insertion end portion116with a reduced diameter that allows the insertion end116to snugly insert through the central orifice54of the first securing member14. The insertion end portion116is axially dimensioned to extend through the first securing member14and into the locking member28via recess118such that the set screw70captures the end portion116. The drill bit is disposed to rotatably capture the first securing member14between a rim wall120, formed by the reduced end portion116, and the outer wall58of the locking member28. The second securing member20is integrally joined to the spring16, and the spring is integrally joined to the rotatable securing member14thereby forming a “spool” that can be rotated upon the drill bit26while being maintained at a predetermined position.

In operation, the drill bit26penetrates a workpiece and disposes the outer wall24of the second securing member20against a workpiece, the hole saw8starts to cut the workpiece and the spring16begins to compress. The force generated by the spring16coupled with the coefficient of friction between the outer wall24of the second securing member20and the workpiece, prevents the spool from rotating thereby transferring friction and wear between the stationary outer wall42of the first member14and the rotating outer wall58of the locking member28. No friction would occur between the rim wall120of the bit26and the inner wall60of the first securing member14due to a slight separation between the walls120and60resulting from the compressed spring16. The damage that would ordinarily result from the friction generated between the outer walls42and58is negated with the application of oil, grease or similar lubricant to the insertion end116of the bit26, and the inner and outer walls60and42of the first securing member14.

While the invention has been described with reference to the details of the embodiment, these details are not intended to limit the scope of the invention as defined in the appended claims.