Hole saw

Cutting by use of rotating axially moving tool – With product handling or receiving means

Patent

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Details

408206, 408209, B23B 4102

Patent

active

050077775

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

This invention relates to piercing means, and more particularly to a hole saw for drilling a hole in a material.


BACKGROUND ART

A hole saw is generally composed of a tubular body having a cutting knife provided at its brim, and a guide drill extending from inside the tubular body to the end part, and by rotating the both together, a hole nearly equal to the outside diameter of the tubular body is drilled in the workpiece while being guided by the guide drill. At this time, as a matter of course, the hole drilled in the workpiece is circular. Therefore, when drilling a circular hole, it was widely believed among the manufacturers in the field of this art that the shape of the tubular body of the hole saw should be preferably circular.
However, when drilling a circular hole by a tubular body of cylindrical shape, the gap between the drilled hole and the tubular body is extremely slight. Therefore, cutting chips pose a serious problem. For example, if the workpiece is a soft iron and when its thickness is over 10 mm, or in the case of ALC plate which generates many cutting chips, the problem becomes manifest.
To solve this chip problem, generally, it is known to form a spiral groove for removing cutting chips on the outer circumference of the tubular body. This groove is, however, generally formed by cutting, which complicates the manufacturing process of hole saw. To discharge chips, the required depth of groove is about 1.0 to 1.5 mm or more, and to form such groove, it is necessary to form the tubular body in a thickness of about 3.0 mm. Therefore, complication of manufacturing process and increase of wall thickness cause to increase the product cost.


DISCLOSURE OF INVENTION

A hole saw according to this invention comprises a drill part for determining the center of piercing with respect to the workpiece, a tubular part possessing plural piercing knives at the end surrounding the circumference of the drill part, and a shank part for fixing the drill part and the rear part of the tubular part and transmitting the torque from a power unit to the both, whereby at least the piercing knife dispositon positions of the tubular part possess portions sequentially different in the distance from the rotary shaft.
In such structure, a space for allowing the cutting chips to escape is provided, and smooth piercing is realized.


BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows a partially cut-away sectional view of one of the embodiments of this invention;
FIG. 2 to FIG. 16 are schematic end sectional views of other embodiments showing the vicinity of piercing knife 2;
FIG. 17 is a front exploded view showing a different embodiment of this invention;
FIG. 18 is an essential part explanatory drawing showing a still different embodiment;
FIG. 19 is a total perspective view showing still another embodiment;
FIG. 20 is an explanatory drawing of other embodiment accessory to the embodiment in FIG. 19; and
FIG. 21 is a total perspective view showing another different embodiment.


BEST MODE FOR CARRYING OUT THE INVENTION

Referring now to the drawings, some of the preferred embodiments are illustratively described below. In the following embodiments, however, the dimensions, materials, configuration and other conditions of the constituent parts mentioned herein are not intended to limit the scope of the invention unless specifically described, and are mere explanatory examples.
One embodiment of this invention is shown in FIG. 1.
A piercing knife (2) is provided at the end (1') of a tubular main body (1), and its basal part (1") is communicated with a shank (3). Around this basal part (1"), a hole communicating from inside to outside the main body is disposed at a proper position.
In a manner to cover the hole (4) from outside, a casing (5) is provided around the surface of the basal part (1"). The casing (5) has a hollow part (6) which is opened to the side opposite to the basal part (1"). The casing (5) also has a tube (7) to communicate with an external vacuum pump (not shown). At the abutting position of

REFERENCES:
patent: 1829659 (1931-10-01), Kefflo
patent: 2179029 (1939-11-01), Barnes
patent: 2349400 (1944-05-01), Beckwith
patent: 2779361 (1957-01-01), McKiff
patent: 2794469 (1957-06-01), Shortell
patent: 3382743 (1968-05-01), Trevathan
patent: 3495359 (1970-02-01), Smith et al.

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