FR2495522A1 - Tang for interchangeable rotary machine tool - has four main flats with secondary flats at thirty degrees to bisectrix of main flats - Google Patents

Abstract

The tang may be incorporated on drill-bits or gimlets having a cross-sectional profile which improves the liaison with a chuck. The profile includes four principal flats (2) at ninety degree intervals together with four ancillary flats (3) at thirty degrees to an axis (4) bisecting two principal flats. Ancillary flats on one side of the axis may extend over a greater axial length together with the principal flat on the opposite side. A circumferential groove may separate the long flats from the shorter flats, the shank between tool and tang being of a reduced diameter.

Description

 The present invention relates to the field of rotary cutting tools, in particular with a device for clamping in mandrels, in particular fitting devices for bits or bits of wood or metal, or other tools of this type, and has for its object such a universal emmanchemertert device.

 Cutting tools of this type currently existing are generally fitted with a fitting device with a cylindrical shank or even with three or hexagon shanks, or with a conical square shank, allowing a more effective clamping of the tool in the chuck.

 However, a tool fitted with such a three or six sided shank cannot be mounted in four-jaw chucks which are common, in particular on hand crankshafts.

 There is also a fitting device in the form of a stepped tail having on one part of its length, near its end, three sides, and on the other part, near the tool, four sides, so that a clamping is possible in two, three or four jaw chucks.

 However, in the case of tightening such a fitting device in a two- or four-jaw chuck, it is necessary that this chuck is very long in order to be able to clamp the shank at the desired location, which is not not the case, for example, for electric or pneumatic hand-held chucks.

 The present invention aims to overcome these drawbacks.

 Its purpose is in fact a universal fitting device for wood or metal drill bits or drills, or other tools of this type, characterized in that the tail is provided, over the same part of its length, with four sides offset at 900 and four sides offset each by 300 relative to a median axis, passing through two of the four sides offset at 900 so as to allow the use of two, three or four jaw chucks.

 According to a characteristic of the invention, two sides offset by 300 on the same side with respect to the median axis, and the face opposite this median axis and these two sides extend over a greater length than the other sections.

 The invention will be better understood thanks to the description below, which relates to preferred embodiments, given by way of nonlimiting examples, and explained with reference to the appended schematic drawing, in which FIG. 1 is a plan view of a fitting device according to the invention; Figure 2 is a view similar to that of Figure 1 of an alternative embodiment of the device, and Figure 3 is a sectional view, on a larger scale, of the fitting device.

 In accordance with the invention, and as shown more particularly, by way of examples, FIGS. 1 to 3 of the appended drawing, the universal fitting device for wicks or drill bits for wood, or metals, or other tools of this type , is characterized in that the tail 1 is provided, over the same part of its length, with four sides 2 offset by 900 and four sides 3 offset by 300 relative to a median axis 4 passing through two opposite sides 2.

 Thanks to this arrangement of flanges 2 and 3, it is possible to introduce a tool provided with this device into a four-jaw chuck using flanges 2, into a three-jaw chuck using two flanges 3 arranged in the same side of the median axis 4 and a pan 2 disposed on the opposite side, so that the three sides are offset by 1200, and in a two-jaw chuck in an angle by pressing these jaws on two diagonally opposite edges 5 delimited by the edges of panels 2 and 3 arranged on the same side of the median axis 4.

 According to a characteristic of the invention, two flaps 3 located on the same side of the median axis 4 and a flap 2 located on the opposite side extend over a greater length of the tail 1 than the other flaps, of so that the positioning of the drill bit or the drill, or the like, in a mandrel is facilitated, because the arrangement of the flaps 2 and 3 relative to the jaws is established beforehand.

 According to an alternative embodiment of the invention, shown in Figure 2, the tail 1 is provided with a groove 6 separating the sides 2 and 3 of greater length from the other sides, so that the possibilities of tightening the device are better defined. In addition, there can be provided, between the tail 1 and the cutting tool 7, a rod 8 of reduced diameter compared to the tail 1, and allowing better clearance for the shavings to be obtained.

 Thanks to the invention, it is possible to produce a universal fitting device for the clamping of tools for drilling, milling, boring, slotting, chiselling, etc., in two-spindle chucks, with three or four jaws, electric or pneumatic drills, fixed or hand, or hand crankshafts, allowing to obtain a greater depth of machining.

 Of course, the invention is not limited to the embodiments described and shown in the accompanying drawing. Modifications remain possible, in particular from the point of view of the constitution of the various elements, or by substitution of technical equivalents, without thereby departing from the scope of protection of the invention.

Claims (4)

- CLAIMS  1. Universal fitting device for wood or metal drill bits or drills, or other tools of this type, characterized in that the shank (1) is provided, over the same part of its length, with four sides (2 ) offset by 900 and four sides (3) offset by 300 relative to a median axis (4) passing through two opposite sides (2).  2. Device according to claim 1, characterized in that two sides (3) located on the same side of the median axis (4) and a flap (2) located on the opposite side extend over a greater length tail (1) than the other sides.  3. Device according to any one of claims 1 and 2, characterized in that the tail (1) is provided with a groove (6) separating the sections (2 and 3) of greater length from the other sections.  4. Device according to any one of claims 1 to 3, characterized in that, between the tail (1) and the cutting tool (7), there is provided a rod (8) of reduced diameter relative to the tail (1).