JPH04101708A - Drill - Google Patents

Abstract

PURPOSE:To enhance cutting quality of a drill by providing a symmetrical edge form excluding a chisel edge and symmetrical plural edge tops in a hole machining drill used for manufacture of machinery and applicances and civil engineering and construction. CONSTITUTION:This drill comprises main cutting edges provided with plural edge tops arranged at an equal distance from the center line of a tool and at an equal angular interval around the center, having an equal height, and inclined from the respective tops parts toward the outside periphery, and center part cutting edges inclined toward the central axis of the tool. In a repolishable straight three-blade drill, for example, a tip is fixed facing downward in the same angle inclination as the edge tip rake angle gammat, with a cutting face in paralled with the bottom surface and with a point P as a fulcrum Further, the drill comprises main cutting edges 71, 72, 73 outside peripheral cutting edges 710, 720, 730 sunk and having cutting faces at an acute angle with the outside periphery in a plan view, a center part cutting edge 81 reaching the central axis 00 of the tool and central cutting edges 82, 83 not reaching the central axis 00 of the tool.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a drill for drilling holes, and is used in a wide range of industrial fields, such as the production of machinery and equipment and the construction of civil engineering and construction.

(Prior art) Regarding twist drills, various methods such as thinning or removing a small part of the center where the sharpness is particularly poor have been adopted as countermeasures against the dull chisel edge. The central issue is how to improve the sharpness of chisel edges.

In clamp trills that use tips, in order to make the requirements for precision regarding the tip and the seat of the tip as loose as possible, there is one tip for cutting the center and one tip for cutting the outer periphery, and the cutting edge has an asymmetrical configuration as a whole. Since there are parts without cutting edges, it is inefficient and there is also a problem of unbalanced cutting resistance.

Therefore, for twist drills, how can we solve the inconvenience of having the center of the cutting edge be the top of the cutting edge, which has poor sharpness, and for clamp drills, how can we arrange the cutting edges symmetrically so that it is easier to achieve high precision? The ultimate problem is to find a way to solve these two problems in a unified manner.

(Means to solve the problem) To summarize, there are three ways to solve the problem:

(1) Eliminate chisel edges with poor cutting performance.

(2) It has a well-balanced and symmetrical solid structure that makes it easy to ensure accuracy.

(3) Has multiple symmetrical cutting edge vertices.

An example of the present invention in which a prototype is used as a prototype will be described below.

In Fig. 1-4', AC, BD, and AB take points E and F that are symmetrical with respect to the tool center line 00 on D, and 00
Connect the intruding point Q above, make EQ the central cutting edge 3 that connects with the main cutting edge EC (taken as 1), and FQ as the main cutting edge FD.
(2) is the central cutting edge 4 that connects with the center cutting edge 4. However, the scooping plane for the central cutting edge 3 is a plane 30 determined by EQ and the tool center line 00, and the scooping plane for the central cutting edge 4 is a plane 40 determined by FQ and the tool center line 00. do. Therefore, the rake angle of the central cutting edge is 0°. Flank surface for center cutting edge 3.4 (Example and operation) (1) When using a twist drill as a prototype Conventional twist drill (when brazing a carbide blade, the main cutting edge 1.
It is formed by cutting off a part of the flank 11.21 for 2. Using a grindstone in which the scooping surface and relief of the central cutting blade are the outline of the axial cross section (indicated by the two-dot chain line), the scooping surface 30 and the relief surface 4 are cut.
1 at the same time, turn the drill 180' again to make the scooping surface 40.
and flank surface 31 can be ground simultaneously. In addition, in order to prepare the cutting edge of the central cutting edge 3.4, it is preferable to lightly hone it with a conical grindstone that is in contact with both cutting edges.

If the angle φ that the central cutting edge 3.4 forms with the direction of the tool center line is approximately equal to the half-vertex angle ρ of the main cutting edge, each main cutting edge and the center cutting edge in the direction perpendicular to the tool center line Since the cutting forces are roughly balanced, the bending of the drill as a whole is small.
Improves the straightness of the hole.

In order to achieve a higher level of balance, the square door can be determined through theoretical calculations and experiments that take into account the rake angle and cutting speed. During re-sharpening of the cutting edge, the flank surface of the main cutting edge 11.2
If only 1 is sharpened, the distance between the vertices E and F will decrease with each re-sharpening, so the scooping surface and flank surface of the central cutting edge must be corrected and re-sharpened using the above-mentioned shaped grindstone every few times of re-sharpening. to restore the distance between vertices.

According to the above-mentioned cutting blade, hole machining progresses while cutting an annular groove having a figure 7 cross section. Since there is no chisel edge, the thrust is small, and the cutting edge is stable, so the hole enlargement is small and the hole has good straightness.

(2) Case of Clamp Trill An example in which the present invention is applied to a clamp trill is shown below. The shape and angle of the chip described below are examples of those that are suitable for practical use, but are not limited thereto.

The basic principles of the cutting blade configuration are: 1) use an indexable insert with three alternating cutting edges whose main cutting edge is an equilateral triangle; 2) use a two-edged tip with two tips of the same size; 3) The structure is such that it does not damage the waiting cutting edge that is not currently involved in cutting. 4) The mounting of the bottom surface of the chip deals with both cases where the surface is parallel to the tool center axis and cases where it is not parallel. Sections 4 to 6 As shown in the figure, 00 is the center axis of the tool, the left depth is 100, the right tip is 200, and both tips are of the same shape and size, and the shapes and dimensions of each part of the left tip will be mainly described.

The basic equilateral triangle GHK on which the main cutting edge 51 (standby main cutting edges are 52 and 53) rests is basically on a plane that includes the tool center axis 00, and GH is at an angle with the tool center axis 00, 9 (approximately 7
0° to 75°). If the apex of the cutting edge is L (M, N for the standby cutting edge) and the outer periphery is appropriate, then the center cutting edge 61 (62.63 for the standby cutting edge) is at an angle θ with the main cutting edge 51.
↓ +60°, the center cutting edge 61 is the tool center axis 00
As a method to prevent the portion P WT protruding from the point P where it intersects with the tip 200 from interfering with the tip 200, a) As shown in FIG. Should it be separated by a distance j (in this case, even if there is an uncut part in the center, it will be easily crushed during cutting) or by degrees? (approximately 1° or less) Adjust or reduce the amount of looking down.

Since each cutting edge is given a relief angle and a rake angle, it is difficult to ensure the accuracy of the flank surface, which is sloped against the bottom surface, and also to ensure the accuracy of the sloped surface on the tool body side, which receives the side surface of the chip. It's not easy to do either.

However, once accuracy is achieved, chips can be quickly replaced.

In order to correct errors in the tip and body side wall surfaces as well as adjust the diameter of the machined hole, the gee side wall surface 04 (
Insert the taper knob 9I between the tip (perpendicular to the bottom surface of the chip), and turn the flat plate 9, 9 + on the wall surface 04 to move and adjust the jib 91 and fix it. A similar mechanism is installed on the tip 200 side, and the position of both taper jibs is adjusted to set the lip hide (relative cutting edge height of the left and right tips) to 0, while adjusting the machined hole diameter based on the larger radius r. Sadanuru.

A thin piece may be inserted between the contact surfaces for adjustment.

Place a protector 1+4 on top of the tip to protect the protruding part of the opposite tip from being damaged by chips.
Stack them and clamp them with bolts.

The upper part of the wall surface 04 is used to prevent the protector from rotating.
It is best to use this as a surface against which the side of the protector will abut.

As for the method of clamping, it is structurally simple to clamp with 1 screw passed through the hole of the perforated chip and a pot. As shown in FIG. 1θ, if a method is used in which a chip without a hole is clamped by a presser foot 14 and a screw l+, the structure becomes somewhat complicated, but this is the case.

bl) When the scooping surface is made parallel to the bottom surface of the tip △ In the case of Fig. 10, the tip is set facing downward at an angle equal to the scooping angle 4 of the blade tip using the point P as a fulcrum.

Although the protruding portion does not cause interference, it is better to sink the main cutting edge so that it forms an acute angle with the outer periphery in a plan view to avoid forming a flash in the machined hole.

Oshie-style is suitable for clamping.

It also serves as a breaker, but care must be taken with its shape and dimensions so as not to impede the flow of chips.

The progress of hole drilling is the same as for the twist drill b2)
It is necessary to make the flank of the main cutting edge perpendicular to the bottom surface of the chip and to sink the cutting edge in the slanted portion sufficiently.

Furthermore, it is necessary to provide the cutting edges 61, 62, and 63 with an appropriate clearance angle so that the clearance surfaces of the cutting edges at the outer peripheral edge do not interfere with the machined hole. Since the flank surface is perpendicular to the bottom surface, it has the advantage of being easy to achieve accuracy.

(3) In the case of a multi-blade drill In the case of a drill with three or more chips, the main cutting edge 71, 7 is smaller than the indexable type.
2.73, and outer circumferential cutting blades 710, 720, and 730 whose scooping surfaces are configured and sunk to form an acute angle with the outer circumference in the plan view.
, a center cutting edge 81 that reaches the tool center axis 00, and center cutting edges 82 and 83 that do not reach the tool center axis 00.

(Effects of the Invention) To enumerate the effects of the present invention, they are as follows: l) There is no dull chisel edge (because the center part is cut with a sharp cutting edge whose apex is at a point equidistant from the center axis of the tool, Cutting power and thrust are small, and sharpness is good.

2) In conventional drills, the tip cutting edge is located at the center of the tool, which has no cutting ability, so it is difficult to attach t1 to the workpiece material, and it may be necessary to slow down the feed, whereas in the present invention, Since the tip of the tool has reliable cutting ability, it has good bite and can drill holes with high efficiency without adjusting the feed.

3) Since the cutting edge does not escape, it is possible to make holes even on sloped surfaces.

4) Since the axial length of the lip part is small, the time from biting to the start of full drilling is short, resulting in high machining efficiency.

5) In the case of a twist drill, the cutting speed of the center cutting edge is low and there is little wear, but the main cutting edge has a high cutting speed and wear is large, so the center cutting edge should be reground every few times. All you have to do is re-polish it, which saves you the trouble of polishing.

6) In the case of a twist drill, it is easy to implement because only the tip of a conventional drill needs to be processed into the shape according to the present invention. This also applies when brazing only the tip with a carbide blade.

7) In the case of a clamp drill, there is no particular difficulty in manufacturing the tip and there is no particular difficulty in manufacturing the drill body.
It is easy to implement and has a wide range of applications if the structure allows adjustment of accuracy and diameter of the machined hole.

8) Since the cutting shoulder width is divided, the flow of chips is smooth and chip disposal is easy.

9) In the case of a clamp trill, there is no missing part of the cutting edge as in the conventional case, so the cutting action is performed on the entire tip, resulting in good cutting efficiency and hole drilling in a short time.

10) The dull chisel edge disappears and a sharp center cutting edge appears, so to make a web,
Set the outer peripheral cutter angle W in the plan view to the angle.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a twist drill to which the present invention is applied, FIG. 2 is a front view of the same, FIG. Figure 3 is 1.2
Fig. 4 is a front view of an example of a clamp trill to which the present invention is applied, in which the bottom surface of the tip is parallel to the tool center axis; Fig. 5m is a cross-sectional view of the jib mechanism shown previously; Figure 6 is a plan view (-immediate sectional view) corresponding to Figure 4, Figure 7 is a partial side view of the two chips arranged parallel to each other with a slight distance between them, and Figure 8 is a partial side view of the two chips placed slightly apart from each other with the point P as the fulcrum. Figure 9 is a partial perspective view of the tip when the cutting edge protrudes in front of the tip on the opposite side is sunk, and Figure 1O is a partial side view when the tip is placed face down. Part of the side view when the scooping surface is parallel to the bottom surface, the first
Figure 1 is a partial side view when the bottom surface of the tip is inclined with respect to the center axis of the tool and the flank surface is perpendicular to the bottom surface, and Figure 12 is a plan view of a three-blade brazing straight drill in which the present invention is applied. Figure 13 is a front view of the chip reaching the center of the figure, and Figure 14 is a side view of the same.The main symbols are as follows. 00... Tool center axis, (twist drill) 1.2... Main cutting edge, 3.4... Center cutting edge, 11.21... Flank surface for each 1.2, 3
0.40... Scooping surface for each center cutting edge 3.4, 31.41... Relief surface for each center cutting edge 3.4, 34... Axial cross section of center cutting edge grinding wheel Contour, (clamp trill) 100...Left tip, 200...Right tip,
+01...The bottom of the left insert is mounted face, 51°52.53...Main cutting edge, 61.62.63...
Center (multi-blade drill) 71.72.73...Outer cutting edge, 81...Center cutting edge that reaches the tool center axis, 82.83...
Center cutting edge that does not reach the tool center axis.

Claims (1)

[Claims] 1. A plurality of cutting edge peaks are provided at equal distances from the tool center line, equiangularly spaced around the center, and of equal height, and a main cutting edge that slopes from each peak toward the outer periphery, and a tool center line. A drill comprising a central cutting edge that is inclined toward the axis.