Cutting by use of rotating axially moving tool – With product handling or receiving means – Ejector
Reexamination Certificate
2001-08-14
2002-06-25
Bishop, Steven C. (Department: 3722)
Cutting by use of rotating axially moving tool
With product handling or receiving means
Ejector
C408S204000, C408S23900A, C408S703000
Reexamination Certificate
active
06409436
ABSTRACT:
BACKGROUND OF THE INVENTION
1.A. Field of the Invention
The present invention relates to saws used for cutting circular holes through objects made of wood and various other materials, of the type utilizing a cylindrical -saw cup coaxially fastened to an arbor holding a pilot drill which protrudes forward of cutting teeth provided on a front annular surface of the saw cup. More particularly the invention relates to a hole saw which automatically ejects a plug sawed from a workpiece, in which hole saw cups of various diameters may readily be interchangeably mounted on a novel arbor-holder by a twisting, snapping action.
2. B. Description of Background Art
In U.S. Pat. Nos. 4,741,651 and 5,096,341, the present inventor disclosed plug ejecting hole saws which utilize a left-hand threaded mandrel or arbor that holds a pilot drill, the shank of which is secured in an enlarged diameter flange or collar located at the front end of the arbor. The arbor is screwed into a threaded, arbor-holder bore disposed coaxially through a bushing or thicker portion of a circular disk-shaped base plate which forms the rear end wall of a cup-shaped saw body which has angled circumferentially spaced apart cutting teeth in the front annular end wall thereof. In a hole saw cup of this type, the front, cup-shaped portion of the saw cup and the thicker rear base plate or arbor-holder bushing are generally fabricated as separate metal parts which are brazed together. Thus, this type of hole saw is sometimes referred to as a “bi-metal” hole saw.
A novel feature of the inventions disclosed in the aforementioned patents of the present inventor comprises left-hand threading of both the outer surface of the arbor and the inner threaded bore through the saw cup base. With this arrangement, when the arbor is threaded counterclockwise into the saw cup arbor-holder bore, as viewed from the front of the saw cup and pilot drill end of the arbor, the front flange portion of the arbor advances rearwardly to seat against the inner front wall surface of the saw cup base. The arbor shank, which protrudes rearwardly from the saw cup base is then secured in the collet of a power drill. When the power drill is powered on to turn the pilot drill bit and saw in the usual clockwise cutting direction, as viewed from the rear, shank end of the bit, a counterclockwise reaction torque is exerted on the saw cup teeth by frictional resistance offered by workpiece in response to the cutting action, tending to further tighten and secure the arbor flange against the inner surface of the saw cup base. When the saw cup has penetrated the thickness of a workpiece such as a door panel, a cylindrically-shaped plug of workpiece material becomes lodged tightly within the saw cup, and in prior art hole saws, is difficult to remove from the saw cup. However, in accordance with the '651 and '341 patents, a plug lodged within the saw cup may readily be ejected by powering the drill in a reverse, i.e., counterclockwise direction after a hole has been bored through a workpiece, while maintaining the saw cup stationary. Rotating the drill shank and arbor in a counterclockwise direction by the power drill causes the arbor to be advanced axially forward within the threaded bore of the saw cup, and the front flange of the arbor to abut the rear surface of the plug and eject it forward out of the saw cup bore.
The above-described plug ejecting feature of hole saws disclosed in the present inventors '651 and '341 patents has provided a highly effective and widely accepted improvement in bimetal hole saws. Subsequent to issuance of those two patents, U.S. Pat. No. 5,435,672 was issued for adapters having a left-hand threaded arbor-receiving bore, and a right-hand external bore. The adapters were designed to be threaded into right-hand threaded arbor-holder bores of existing saw cups, thus accommodating left-hand threaded arbors and permitting the present inventor's novel plug ejecting function to be accomplished using existing hole saw cups having right-hand threaded arbor-holder bores.
Although the novel plug ejecting hole saws disclosed in the present inventor's '651 and '341 patents constituted a substantial advancement in the art for hole saws having a base provided with a threaded bore for receiving an arbor, there is another type of widely employed hole saw cup which heretofore could not utilize the advantageous plug ejecting construction disclosed in those patents. This type of hole saw is sometimes referred to as a “Carbon” type, since it uses hole saw cups fabricated as a unitary structure, e.g., a deep drawn cup, made from high carbon steel. In this type of hole saw, the saw cup base is made of relatively thin stock, thus precluding the use of threaded bore through the base as a means for attaching the saw cup to an arbor. Instead, this type of hole saw typically is provided with a non-circular, e.g., a double-D-shaped central bore through the base of the hole saw cup, which receives the complementary-shaped, enlarged rear portion of an arbor which is secured to the base by a threaded fastening member.. The present invention was conceived of to provide a plug ejecting hole saw which may utilize thin base wall, non-threaded saw cups of the type described above.
OBJECTS OF THE INVENTION
An object of the present invention is to provide a plug ejecting hole saw including an arbor-holder which can be attached to hole saw cups of various sizes.
Another object of the invention is to provide a plug ejecting hole saw including an arbor-holder which can be secured to the base of a hole saw cup with non-threaded fastening means.
Another object of the invention is to provide a plug ejecting hole saw including a hole saw cup having a right-hand threaded arbor-securing bore through the base of the hole saw cup, and an arbor-holder or adapter press fittable into the arbor securing bore of the saw cup and having through the adapter a left-hand threaded bore for threadingly receiving an arbor.
Another object of the invention is to provide a plug ejecting hole saw including an arbor-holder which is removably securable to the base of a non-threaded hole saw cup having an unthreaded aperture through the base of the hole saw cup for attaching to an arbor, the arbor-holder having therethrough an axially disposed left-hand threaded bore for threadingly receiving an arbor.
Another object of the invention is to provide a plug ejecting hole saw including an arbor-holder which is removably securable in an unthreaded aperture through the base of a hole saw cup, without accessing the interior of the hole saw cup.
Another object of the invention is to provide a plug ejecting hole saw including an arbor-holder which is removably securable to a hole saw cup provided with a non-circular aperture through its base, the arbor-holder having a front nose piece insertable forward through the aperture, and locking tabs which spring forward to lock the arbor-holder axially with respect to the saw cup when the arbor-holder is rotated with respect to the saw cup base.
Another object of the invention is to provide a plug ejecting hole saw including an arbor-holder having an outer collar and inner body disposed axially therethrough, the inner body having a lefthand threaded bore disposed axially therethrough for receiving an arbor, a front nose piece slidably holding locking tabs and circumferential grooves which cooperate to lockingly engage the base of a hole saw cup when the front nose piece has been inserted into and rotated in a first direction within an aperture provided through the base of saw cup, the locking tabs and grooves being released from locking engagement with the saw cup base when the collar of the arbor-holder is pulled axially rearward with respect to the inner body thereof and rotated in the opposite direction.
Another object of the invention is to provide a plug ejecting hole saw including an arbor-holder having an outer collar which axially slidably holds an inner body having disposed axially therethrough a left-hand thread for
Bishop Steven C.
Chapin William L.
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