JPS6094210A - Twist drill for countersinking hole - Google Patents

Abstract

PURPOSE:To accomplish smooth machining by providing the forward end portion of a twist drill with a groove portion having a twist opposite to that of a usual twist drill groove, a cutting edge twisted reversely formed on the leading edge corresponding portion of the groove portion and a front surface formed on the groove portion along the cutting edge. CONSTITUTION:A drill groove 1, a margin 2, a relieving surface 3 and a subsidiary cutting edge 4 are formed on the forward end portion of a twist drill along the forward twist, and a pilot P inserted in a lower hole is disposed on the most forward end. In this arrangement, reverse-twisting groove portion 5 is formed on the forward end portions of the margin 2 and the relieving surface 3 in such a manner as to intersect the twist drill groove 1. A main cutting edge 6 is formed on a portion where the groove portion 5, the margin 2 and the relieving surface 3 intersect one another, that is, the leading edge corresponding portion of the groove portion 5. A front surface 7 is disposed on the groove portion 5 side of the main cutting edge 6. In this arrangement, chops produced by cutting is passed along the front surface 7 and fed out to the forward end by the groove portion 5 to attain the desired end.

Description

[Detailed Description of the Invention] This invention relates to a drill for hole preparation, which is used when enlarging or finishing an already machined pilot hole to a desired hole diameter by using it as a pilot hole. .

Core drills, shell drills, etc. are known as drills used for finishing after drilling the pilot hole. It twists in the direction of the shaft, and chips are discharged from the tip toward the shank. Therefore, if the thickness of the workpiece is large and the total length of the drill is long, the chip evacuation resistance will increase and casting or ejection may not be carried out in the same place, or the chips in the groove will become an obstacle to the supply of cutting oil. may become insufficient, which may adversely affect machining accuracy and machining speed.

The present invention has focused on these problems, and has been made with the aim of providing a hole-drilling drill that can perform simple machining. A cutting edge with a reverse helix formed in a portion corresponding to the leading edge of the groove, and a rake face formed in the groove along the cutting edge. It is said that That is, in the present invention, since the cutting edge at the tip has a reverse twist K, when cleaning the pilot hole while rotating in a predetermined direction, chips will scrape over the rake surface and form the reverse twist groove. 1. Even if the workpiece becomes thick, it is possible to smoothly discharge chips and supply cutting oil.

In addition, the forward direction of twist in wood 1 thin @Ft/C is
K114 refers to a twist in the direction in which chips are ejected from the shank by rotation in a predetermined direction, like in a normal drill groove, and a twist in the opposite direction to the above.

First, the configuration of the cutting edge portion of the present invention will be explained with reference to FIG.
do. Note that, although the zero-start IJi does not necessarily require a normal drill groove in a normal drill, a case with a normal drill groove will be described for ease of understanding.

FIG. 1(a) shows a side view of the drill lead part 11, and (1
) is the drill groove, (2) the nail L margin, (3) - the second chamfer, and (4) is the minor cutting edge, which are formed with a sequential helix like the drill of thread 1; A pilot P to be pushed into the prepared hole is provided at the tip of the of5n-i margin (2) and a second take-off...The tip of the 1 (3) is formed to intersect with the drill groove (1). It is a groove-like part.

This groove-like part f51 does not necessarily have to be a spiral shape like a drill groove (+l), but may be a straight line or an arc shape with a large radius of curvature, or it can be formed so that its direction is reversely twisted. The inclination angle θ of the groove (6), which corresponds to the helix angle in the spiral groove, varies depending on the material of the workpiece and cutting conditions, but good results are obtained when it is selected to be around 40' to 55°. Easy to obtain, especially from 45° to 50°
The best results were obtained in the case of (6) is the groove-like part (5
) is the cutting edge formed at the part where the first cut (2) and the second cut face (3) intersect, that is, the part corresponding to the leading edge of the groove (5), and the main cut in this drill is It is equivalent to a blade.

A rake face (γ) is provided on the side of the groove (5) of the cutting edge (6) so that an appropriate rake angle is formed.

The cross-sectional shape of this rake face (7) is similar to that of a normal cutting tool, and is generally straight on the side closer to the cutting edge (6), but curves as it moves away from the cutting edge (6). It follows the groove (5) smoothly or at a certain angle.

@Figure 1 (b) Partial upper and lower hole diameter A1 of F'i cutting edge (6)
And finishing hole diameter A! FIG. 3 is an explanatory diagram of the N section of FIG. The diameter A3 of the second hole (3) is smaller than the pilot hole diameter A by the amount of clearance, and is the same as the finished hole diameter A of margin (2). Rotate the drill in the direction of arrow C2 while feeding the force in the direction of arrow C□. started,
Main cutting is performed at point B2, which has the same diameter as the finished hole diameter A, and finishing cutting is performed at point B3 at the end.

That is, B1. Tsukara B3. (up to +7) Since it acts as a cutting edge on the secondary surface, the machining allowance A4 is removed and the six holes of the hole diameter A2 are cut. (7a) shows the bottom of the rake face (7). The chips generated by such cutting are scraped toward the center of the pilot hole by the action of the rake (71-), f!
: While being rubbed, it is twisted in the opposite direction and sent out in the distal direction by the groove-shaped part f[i+.

In addition, except for the above, the shape of a normal drill is assumed.
-1-rFr 7 days 4 +1. θ) -71 forces, entering 6;
Tenth day 1: 2r Lq 17% IH-@1 figure (b)
As shown by the broken line in the figure above, increase the radius of curvature of the part that becomes gentler from the margin (2) to the second cut surface (3).
It is preferable to have a cross-sectional shape in which the outer diameter changes gradually, and to form the cutting edge (6) along this broken line.
By doing this, the cutting start point B1 will be moved to the front end of the cutting edge (6), and almost the entire range of the 9J''L blade (6) will be effectively utilized, cutting will be performed little by little, and the cutting resistance will be dispersed. This makes it easier to obtain a good finish.

Next, several illustrated embodiments will be described.

FIGS. 2(a) and 2(b) show an example in which the Kihatsu +41 was applied to a normal drill, that is, a drill that rotates clockwise when viewed from the shank side and has a right-handed helical groove.

As shown, the drill groove (1) is twisted in the forward direction.

Margin (2), secondary cutting edge (3), subcutting edge (4) U
Both are formed similarly to normal drills. (5)
is the groove f1 where the main cutting edge is provided in the case of a normal drill)
A short length formed to intersect with the leading edge of V,
, Naomisaki Musu Formation H-Jukkoku Formation The water is formed by this groove-like part (5) and groove (+l), which is also narrow in width and inclined in the direction of reverse twist. Note that this groove (
5) may have an uneven length and may be formed in the shape of a mere notch. A cutting edge (6) is formed at a portion corresponding to the leading edge of the grooved portion (5).
A rake face (7) is provided on the side of the groove-shaped portion (5) of 6) to form an appropriate rake angle. Further, a relief surface may be formed on the side of the second chamfer surface (3) if necessary.

@2 Figure (C) illustrates the positional relationship of the grooved part (5) with respect to a normal drill having a main cutting edge (river, main relief 1i02) and a chisel edge (13), and the grooved part +51
Most of the Fi main cutting edge (11) is notched to create a groove (formed from 11 to the main flank (121K). Chisel edge 03) may be left in place, but if the hole is insufficient or unused. Since it is unnecessary as a trim, in this example, #-1' is cut to form a flat part (8).
It is configured as described above for the Kinotsu family example, and when machining such as finishing the pilot hole is performed while rotating in a predetermined direction, that is, clockwise when viewed from the shank side, as with a normal drill, the cutting edge ( The chips generated by cutting by the rake 111 (7) are continuously scraped out toward the center of the prepared hole by the action of the rake 111 (7), and are further removed from the cutting edge (6) and the groove (5).
) has a reverse twist, so it is fed in the direction of the tip, contrary to a normal drill, and is ejected from the opposite side of the workpiece through the pilot hole.

As described above, according to the present invention, chips are discharged in the direction of the tip, so the groove fl+ is not used for discharging chips, but is mainly used for supplying cutting oil. . The embodiment shown in Fig. 3 is designed to more fully utilize this cutting oil supply function. A right-handed helical groove is provided continuously along almost the entire length of the pode over the range in which it is normally provided, and at the tip is a groove-shaped portion (5) according to the present invention, a cutting edge (6), and a rake face (
7) is provided. Therefore, when rotated in a certain direction, the groove (
1a) exerts a screw action to send the cutting oil in the direction of completion, and lubrication with the cutting oil is performed semi-forcibly. Therefore, even when the workpiece is thick and the drill length is long, cutting oil can be reliably supplied and machining speed can be increased.

Note that the frill groove (1a) is continuously formed at the tip of the groove (1a), and the inclination angle and twist angle of both are h.
The angle is selected to suit the application.

Figure 4 is another embodiment, showing an example in which the present invention is applied to a combination drill that has a reamer section in the middle part of the body. Screw 1. The reamer blade and reamer groove are formed in a continuous spiral over almost the entire length of the tip carabody, and the reamer blade and reamer groove of the reamer portion are aligned with the land l/? of the drill. 24i
, I won! l
719 official publication (Yuusho). This type of combination drill has the advantage of being able to efficiently perform hole drilling with a drill and internal finishing with a reamer at the same time. (9JF of the drill via the drill groove)
< When the chips are discharged, the discharge may be obstructed by the chips left by the reamer blade.

In particular, when the thickness of the workpiece is large and the total length of the tool is long, the chip evacuation resistance increases, the machining time becomes longer, and the amount of chips generated increases. For this reason, if you do not pull out the drill and remove the chips during machining, the chips may get caught and damage the workpiece or make it impossible to process, making handling troublesome and reducing work efficiency. decreases.

The present invention is particularly suitable for solving such problems, and will be described below with reference to FIG. 4.

In Figure 4, 6! 1) is a combination drill in which a pilot P1 drill part, a reamer part R1 and R1, and a shank S are formed in series from the tip to the rear end K on the axis XX. Drill groove (No. 2 corresponds to the groove fl+ in Figures 1 and 2, and the pilot P
From the tip of to the boundary between reamer R1 and shank S,
It is formed continuously with a sequential twist.

+21 fil is the margin and second chamfer of the drill part.

Reamer parts R1 and Rzi, L, a drill groove (24 is provided with a reamer blade (C) and a reamer groove formed with a reverse twist. This reamer blade 匈) and a reamer groove (24) Vi,
1. A land part with a diameter slightly larger than the drill part is provided between the two wood drill grooves. In addition, the diameter of the reamed portion R1 is larger than that of the reamed portion R1.

The helix angle of the reamer blade is selected to be in the range of 40° to 65°, whereas the helix angle of a normal reamer is 4° to 10°. In addition, the reamer groove (4) is shallower than the drill groove, and the reamer blade (4)) and the reamer groove (inside the reamer groove) are 9J in the part where they intersect with the drill groove (2). Groove (2411i) Both grooves are drill grooves (2
It is connected to the In this way, the reamer 4) is divided by the drill groove □□□, but if it is considered as a continuous spiral shape, the number of teeth is 4 for all diameters.
If it is thick, it is selected as 6 or more. (a) and 6) are respectively reamer blades f231
K Offshore L4e This is the margin and flank formed by the seam.

At the tip of the drill portion, a groove (5), a cutting edge (6), and a rake (7) according to the present invention are formed as in FIG. 1.

The present embodiment is configured as described above, and when finishing the pilot hole, first the cutting edge (6) performs drilling to cut the inward direction of the pilot hole, and then the reamer portion R1
Reaming is performed by R and R to finish the inner surface. Here, chips produced by the cutting edge (6) of the drill portion are sent toward the tip, pass through the drill groove hole formed up to the pilot P portion, and are discharged to the outside through the pilot hole. In other words, since chips from drilling are not fed into the drill grooves of the reamed parts R1 and R2 (2), there is no interference with the chips from reaming, and machining can be interrupted. There is no longer any need to remove chips using a screwdriver, and continuous machining is possible even in the case of thick workpieces.Therefore, the drill reamer is integrated, and the reamer blade has a reverse helix with a large helix angle. As a result, the qS length of this type of combination drill can be fully utilized, allowing highly accurate machining to be carried out in a short period of time.

The reason why the reamed portion is formed in two stages in this embodiment is to achieve more accurate finishing by reducing the amount of reaming per stage and performing the reaming process in two steps. By the way, when drilling the pilot hole using the drill of this example, it was possible to easily obtain an accuracy within tO,01 using a general-purpose machine tool.

Furthermore, the function of the above embodiment to eject chips from the drill groove (2, IJ, and S) in the direction of the shank S is unnecessary, and chips from reaming are eliminated!
J-MafM (24) Kara 4J'l out, h
II': t: , t: Inote, m-r Rei (7) It is possible to make a screw with a smaller helix angle than that of a drill, for example about 15° or less, and it can be made into a corner, and in extreme cases (I:l Stray without twisting) tM may also be used.Also, if the thickness of the reamed material is large, lengthen the neck part between the reamer part and the shank, and insert a guide F here.
A cylindrical part of the shape is provided, and a groove with a reverse helix is formed on the surface of the cylindrical part with a helix h angle of 35° to 40°.
By communicating with (22), it is possible to increase the cutting oil supply power by utilizing the screw action of the reversely twisted groove.

As mentioned above, the zero-bore 1 hole cleaning drill has a reverse-twisted cutting edge installed at the tip that ejects chips toward the tip. Oil is supplied smoothly, making it easy to increase machining accuracy and machining speed while using general-purpose machine tools.

[Brief explanation of the drawing]

FIG. 1(a) is a side view of the main part showing the shape of the blade of the present invention;
Fig. 1(b) An explanatory diagram of the relationship with the Fi cutter 1-blade hole, @
Figure 2 (a) Side view of essential parts of H-Example, Figure 2 (b)
Figure 2(c) is a front view of the tip showing the comparison between the same as above and a normal drill, Figure @3 is a side view of the main part of another example, and Figure wJ4 is different. FIG. 3 is a side view of the embodiment of FIG. (6)...Groove, (6)...Cutting edge, (7)...
・Rake face. Patent applicant: Mr. Densanbu Sakai, attorney: Shino, patent attorney: 1) Minoru

Claims (1)

[Claims] [11 A grooved part having a twist opposite to that of a normal drill groove at the tip, a reversely twisted cutting edge formed in a part corresponding to the leading edge of this groove, and a cutting edge along this cutting edge. A drill for drilling a hole, characterized in that the rake faces formed in the groove-like portion are rounded.