JP2006205272A - Double margin drill - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable boring work of high finishing accuracy, by enhancing guide performance in biting and penetration, by approaching a starting position of a first margin and a second margin, without reducing chip discharge performance, in a double margin twist drill of applying thinning. <P>SOLUTION: The first margin 1 succeeding to an outer peripheral cutting edge 7 and the second margin 2 parallel to the first margin 1, are formed on land 8. The second margin 2 is arranged on the land 8 by separating from a crossing line 3 formed of a heel 3, that is, a relieving surface 31 and a groove 4. The outermost point 91 of a crossing edge 9 of the tinning 11 and a flank 71 of the tip cutting edge 7, exists between the second margin 2 and the heel 3. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention includes a drill body, a pair of thin chip discharge grooves formed on the outer peripheral surface of the drill body, and a land having a tip cutting edge and a peripheral cutting edge following the tip cutting edge. And a double margin twist drill in which a first margin following the outer peripheral cutting edge and a second margin parallel to the first margin are formed on the land.

Conventionally, twist drilling has a limit in machining accuracy, and it is difficult to machine a hole diameter, roundness, surface roughness and the like with high accuracy. In drilling, it is known that a double margin drill is effective for improving processing accuracy. This is because the double margin twist drill contacts the processing hole at four points, that is, contacts at the four points of the pair of the first margin and the second margin, and the guide performance is improved as compared with a normal twist drill. Patent Document 1 (JIS B0171 No. 1403) describes a double margin twist drill. In the conventional double margin twist drill, in order to improve the biting property and reduce the thrust force, as shown in the partial side view of the tip portion of the conventional double margin twist drill in FIG. Is often used with X-shaped thinning 11 applied.
JIS B0171 No.1403

  When thinning 11, such as X-shaped thinning, is performed as shown in the partial side view of the tip of the conventional double margin twist drill in FIG. 3A, the heel 30 side from the tip cutting edge flank 13 passing through the drill axis. Since the thinning 11 is formed at an angle toward the second margin 20, the second margin 20 is provided adjacent to the heel 30, that is, the intersection line 30 formed by the second picking surface 21 and the groove 40. The start position of the margin 20 is largely retracted, the axial difference L3 from the start position of the first margin 10 is increased, and the guide performance is lowered. When an attempt was made to reduce the axial difference L3 between the first margin 10 and the start position of the second margin 20, the chip pocket of the thinning portion was reduced, reducing chip discharge and reducing finishing accuracy.

  The problem of the present invention is that, in a double margin twist drill subjected to thinning, the start positions of the first margin and the second margin are brought close to each other without lowering the chip discharge performance, and the guide property at the time of biting and penetration is high. An object of the present invention is to provide a double margin twist drill that enables drilling with high finishing accuracy.

  For this reason, the present invention includes a drill body, a land having a tip cutting edge and a peripheral cutting edge following the tip cutting edge, each formed in a pair on the outer peripheral surface of the drill body, a chip discharge groove subjected to thinning, The land has a first margin following the outer peripheral cutting edge and a second margin parallel to the first margin, and the second margin is formed by a heel, that is, a second face and the groove. A double margin drill characterized in that the outermost point of the intersecting ridge between the thinning and the cutting edge flank is located between the second margin and the heel. The above-mentioned problems were solved by providing

  In the present invention, in the double margin drill in which the first margin, the second margin parallel to the first margin, and the thinning are formed, the second margin is disposed on the land apart from the heel. 2 The starting position of the margin is approached, the difference in the axial direction is reduced, the guideability at the time of biting and penetration is improved, the finishing accuracy is improved, and the intersection ridge between the thinning and the cutting edge flank Because the outer point is located between the second margin and the heel, the double margin twist drill that enables drilling without enlarging the chip discharge by increasing the chip pocket formed by the thinning part Became to provide.

  Preferably, the second margin is formed adjacent to the first margin, or the second margin is formed on the land so as to be separated from the heel by the width of the first margin. Is desirable.

  The best mode for carrying out the present invention will be described with reference to FIGS. FIG. 1A is a partial side view of a drill tip portion, FIG. 2B is a front view of a drill tip portion, and FIG. 2 is a second view of the present invention of a double margin twist drill showing a first embodiment of the present invention. (A) of the double margin twist drill which shows this embodiment shows the partial side view of a drill front-end | tip part, (b) shows the front view of a drill front-end | tip part, respectively.

  The twist drill according to the first embodiment of the present invention includes a drill body 5 and a land having a tip cutting edge 6 and a peripheral cutting edge 7 following the tip cutting edge 6 formed in a pair on the outer peripheral surface of the drill body 5. 8 and a chip discharge groove 4 to which a thinning 11 is applied. A first margin 1 following the outer peripheral cutting edge 7 and a second margin 2 parallel to the first margin 1 are formed on the land 8. The second margin 2 is located on the land 8 apart from the heel 3, that is, the intersection line 3 formed by the second face 31 and the groove 4, and the thinning 11 and the tip edge 7 intersecting ridges 9 of the flank 71 The outermost point 91 is between the second margin 2 and the heel 3.

  With this configuration, in the first embodiment of the present invention, in the double margin drill in which the first margin 1 and the second margin 2 parallel to the first margin 1 and the thinning 11 are formed, the second margin 2 is the heel 3. Since it is placed on the land 8 away from the center, the starting positions of the first margin 1 and the second margin 2 are brought closer to each other, the axial difference L1 is reduced, and the guideability at the time of biting and penetration is improved and improved. However, in through-hole processing, etc., by guiding with 4 margins 1 and 2 from the entrance to the exit of the hole, improving the finishing accuracy, such as ensuring good hole accuracy from the entrance to the exit of the hole, And the thinning 11 and the tip cutting edge 7 The outermost point 91 of the intersecting ridge 9 of the flank 71 is between the second margin 2 and the heel 3, so the chip pocket formed by the thinning part is enlarged. , Cut We have provided a double margin twist drill that enables drilling without reducing chip discharge.

  In the first embodiment of the present invention shown in FIG. 1, the second margin 2 having an outer diameter of 7 mm, a groove length of 150 mm, an overall length of 195 mm (only the drill tip is shown), and a handle diameter of 7 mm is changed to the first margin 1. The thinning portion is formed adjacent to each other so that the starting positions of the first margin 1 and the second margin 2 are made closer and the axial difference L1 is made smaller. As a result, a large chip pocket can be secured, and drilling can be performed without reducing the chip discharge performance.

  In the second embodiment of the present invention shown in FIG. 2, the second margin 2 having an outer diameter of 7 mm, a groove length of 150 mm, an overall length of 195 mm (only the tip of the drill is shown) and a handle diameter of 7 mm is substantially The first margin 1 is formed on the land 8 separated by a margin width t, and the distance between the first margin 1 and the second margin 2 and the axial difference L2 are as shown in FIG. 1 according to the first embodiment of the present invention. A little larger, improved guideability and improved finishing accuracy. The first thinning 11a and the second thinning 11b are provided so that a chip pocket formed by the thinning portion can be sufficiently secured.

(A) of the double margin twist drill which shows the 1st Embodiment of this invention is a partial side view of a drill front-end | tip part, (b) is a front view of a drill front-end | tip part. Respectively. (A) of the double margin twist drill which shows the 2nd Embodiment of this invention is a partial side view of a drill front-end | tip part, (b) is a front view of a drill front-end | tip part. (A) of the conventional double margin twist drill is a partial side view of a drill front-end | tip part, (b) is a front view of a drill front-end | tip part.

Explanation of symbols

1: First margin 2: Second margin 3: Heel 4: Chip discharge groove 5: Drill body 6: Tip cutting edge 7: Peripheral cutting edge 8: Land 9: Cross ridge 11,11a, 11b: Thinning
31: Cutting edge flank 91: Outermost point of intersection ridge

Claims (3)

  A drill body, a pair of lands formed on the outer peripheral surface of the drill body, each having a tip cutting edge and an outer peripheral cutting edge following the tip cutting edge, and a chip discharge groove provided with a thinning. The first margin following the outer peripheral cutting edge and the second margin parallel to the first margin are formed, and the second margin is separated from the heel, that is, the intersection line formed by the second face and the groove. The double margin drill is arranged on the land, and an outermost point of an intersection ridge between the thinning and the tip cutting edge flank is between the second margin and the heel.   The double margin drill according to claim 1, wherein the second margin is formed adjacent to the first margin.   2. The double margin drill according to claim 1, wherein the second margin is formed in the land so as to be separated from the heel by a width of the first margin. 3.

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