JPS624515A - Drill tap - Google Patents

Abstract

PURPOSE:To simplify a process forming a thread hole and decrease its machining time, by executing at a stroke a prepared hole drilling process and a tapping process. CONSTITUTION:A drill tap 20 helically forms drill cutting edges 28a-28c and tap cutting edges 30a-30c with a predetermined space apart on the same lands 32a-32c constituting edge parts 22a-22c. Further the drill cutting edge is constituted so that it is positioned in the front of a rotary direction of cutting for the tap cutting edge. If the drill tap is fed to a work, the drill cutting edge starts cutting for drilling a prepared hole in the work. The drill tap discharges cutting chips via clearance flutes 38a-38c. The tap cutting edge performs tapping of the prepared hole immediately after it is cut by the drill cutting edge. Accordingly, the drill tap substantially improves its production efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a drill tap, and more particularly to a drill tap that can simultaneously perform a pilot hole drilling step and a tuffing step when forming a screw hole.

Generally, when forming a threaded hole, a pilot hole is drilled with a drill, and then a tap is threaded into the pilot hole to perform threading, that is, tapping. Therefore, in order to form one screw hole, it is necessary to perform two steps: a pilot hole drilling step and a tuffing step. As a result of requiring these two processing steps, it takes a considerable amount of time to form the short holes, and the process of forming the short holes is complicated because it requires replacing the drill and tap or involves moving the workpiece. There was a problem with that.

Therefore, in order to overcome these difficulties, a drill tap as shown in FIG. 1 is used. That is, this drill tap 2 has a drill part 4, a tap part 6, and a handle part 8 formed continuously in the axial direction, and the workpiece is inserted into the boundary between the drill part 4 and the tap part 6 by the drill part 4. Groove part ・1 for polishing the peripheral edge of the lower flame drilled in the
0 is formed.

Therefore, in the above configuration, when forming a short hole using the drill tap 2, first, the drill portion 4 drills a pilot hole by feeding the drill tap 2 into the workpiece while rotating it, and then, Tapping is performed by screwing the tap portion 6 into the prepared hole to form a short hole.

By the way, since the drill tap 2 is simply a combination of a conventional drill and a tap in the axial direction, the overall length of the drill tap 2 must be relatively long. Therefore, the drill tap 2 has a disadvantage in that its strength against bending stress is low and it is easily broken. Moreover, as described above, the drill tap 2 generally has the groove 10, and therefore, stress is concentrated in the groove 10 during cutting work, especially when processing a hard workpiece. It has also been pointed out that there is a tendency for breakage to occur from the groove portion 10. In addition, since the drill part 4 is always fed into the workpiece before the tap part 1, an unnecessary hole continuous to the short hole is drilled in the workpiece, and this is not suitable for thin-walled workpieces. It has been pointed out that a short hole cannot be formed without drilling a through hole.

Therefore, as a result of intensive research and ingenuity, the inventor of the present invention found that
If a plurality of cutting edges consisting of a drill cutting edge and a tap cutting edge are formed in the main body part of the drill tap, and these are configured to extend in a spiral shape, the workpiece can be cut by rotating the drill tap main body. On the other hand, first, the drill cutting edge forms the tuffing, and then the tap cutting edge performs the tuffing, thereby converting the two processes of pilot hole drilling and tapping using a conventional drill and tap into a single process. The process is simplified, and even compared to the drill tap 2 shown in Fig. 1, the time required for the short hole forming process is not only shortened, but the strength of the drill tap itself is also improved. It has been found that it is now possible to form a short hole without drilling a large hole, and that the above-mentioned disadvantages can be eliminated.

Therefore, in the short hole forming process, the present invention can simplify the short hole forming process and shorten the machining time by performing the pilot hole drilling process and the tuffing process at the same time. To provide a drill tap with excellent strength without drilling unnecessary holes.

In order to achieve the above object, the present invention provides a drill tap having a handle and a plurality of spirally extending blades.
A drill cutting edge and a tap cutting edge are spaced apart by a predetermined distance and formed in a spiral shape on the same land constituting each of the blade parts, and the drill cutting edge is positioned forward in the cutting rotation direction with respect to the tap cutting edge. It is characterized by being configured such that the

Next, preferred embodiments of the drill tap according to the present invention will be described in detail with reference to the accompanying drawings.

In FIG. 2, reference numeral 20 indicates a drill tap;
This drill tap 20 has three blades 22a extending spirally at a predetermined distance, like a general twist drill.
, 22b, 22c, and a handle 24 for connection to a rotational drive source (not shown). In this case, since the blade parts 22a to 22c all have the same shape, only the blade part 22a will be explained.

The blade portion 22a includes a drill cutting edge 28a and a tap cutting edge 30a formed on the same land (a third
(see figure). In this case, the drill cutting edge 28a and the tap cutting edge 3
The positional relationship of 0a is that when the drill tap 20 is rotated in the direction of arrow A in the figure, the drill cutting edge 28a is the tap cutting edge 30a.
Configure it so that it takes precedence over . Drill cutting blade 28a
is a cutting edge for forming a lower flame and extends in a spiral shape, while the tap cutting edge 30a is a cutting edge for tapping, and the drill cutting edge 28a and the tap cutting edge 30a are on the same land. 32a.

The tap cutting edge 30a extends parallel to and spirally with respect to the drill cutting edge 28a. That is, the tap cutting edge 30
As shown in FIG. 2, a has a cutting edge portion that defines a large number of tap grooves, and in order to cut a predetermined screw groove, the groove has one central axis centered on the axis of the drill tap 20. It is formed to be located on a spiral line. In addition, tap cutting blade 30
The radial length of a is selected to be large so that it protrudes further outward than the drill cutting edge 28a.

Furthermore, in the land 32a, a relatively shallow relief groove 36a is formed at the boundary between the drill cutting edge 28a and the tap cutting edge 30a.
form. This escape groove 36a is for releasing cutting waste generated by the tap cutting edge 30a. Furthermore, an inclined surface is formed on the surface portion of the tip of the drill cutting edge 28a, thereby providing a relief angle θ for suitably cutting the workpiece.

The surface portion at the tip of the tap cutting edge 30a is formed to have an angle θ2 that further widens the clearance angle θ1 (see FIG. 4).

The blade portion 22a is configured as described above, and as described above, the blade portions 22b and 22c have the same shape as the blade portion 22a, so a detailed explanation thereof will be omitted.

In addition, in the blade parts 22b and 22c in the figure, the blade part 2
Components equivalent to 2a are indicated by reference numerals having the same number part, and the reference numeral 2a or C is added to the numeral part corresponding to the blade parts 22b and 22c.

On the other hand, between the blade part 22a and the blade part 22c, that is, between the drill cutting edge 28a and the tap cutting edge 30c, there is a relatively deep relief groove for guiding the cutting waste generated by the drill cutting edge 28a to the outside. 38a. Similarly, there is also a relief groove 3 between the drill cutting edge 28b and the tap cutting edge 30a.
8b, and an escape groove 38c is also formed between the drill cutting edge 28c and the tap cutting edge 30b. The side relief grooves 38a to 38c are formed so as to be inclined toward the center of the tip of the drill tap 20 at one end thereof.

The drill tap according to the present invention is basically constructed as described above, and its operation and effects will be explained next.

The handle 24 of the drill tap 20 is firmly connected to a rotational drive source via a chuck (not shown), and the rotational drive source is started to rotate the drill tap 20 in the direction of arrow A in the figure. Therefore, when the drill tap 20 is fed into the workpiece along its axial direction, the tip of the drill tap 20 starts cutting the workpiece. In this case, first, the drill cutting blades 28a to 28c start cutting the workpiece in order to drill a pilot hole. The cutting waste generated by this pilot hole drilling process is transferred to the handle portion 24 along the spiral escape grooves 38a to 38c.
transported in the direction. In this case, as can be understood from FIG. 3, since the escape grooves 38a to 38c are formed deeply, a relatively large amount of cutting waste generated by the trill cutting edges 28a to 28c can be easily guided to the outside. I can do it.

On the other hand, the tap cutting edges 30a to 30c are the drill cutting edges 2.
It rotates integrally with 8a to 28G. That is, the blade part 2
2a, a pilot hole is first formed by the rotating drill cutting edge 28a, and immediately after that, a tap cutting edge 30a protruding outward from the drill cutting edge 28a taps the peripheral surface defining the pilot hole. Therefore, the process of drilling a pilot hole using the drill cutting blades 28a to 28c is accompanied by the tapping process using the tap cutting blades 3'Oa to 30c.

Therefore, if the speed of rotation and feed applied to the drill tap 20 is appropriately selected in advance and the workpiece is cut, a short hole can be formed at once. At this time, tap cutting blade 30
A relatively small amount of cutting waste generated by the grooves a to 30c is transferred toward the handle 24 along the escape grooves 36a to 36c. Since the release route of cutting waste generated by such tap cutting blades 30a to 30C and the release route of cutting waste generated by the aforementioned drill cutting blades 28a to 28c are formed to be different from each other, each cutting waste is separated from the other. Therefore, the cutting debris is smoothly sent out to the outside, and as a result, the cutting resistance is reduced, making it possible to cut the workpiece more easily. There is. Further, at the tip of the drill tap 20, as shown in FIG. 4, since a sufficient relief angle is ensured, generation of cutting heat due to friction during cutting is suitably suppressed.

By using the drill tap 20 as described above, a short hole can be formed in a short time by a single process. A comparison between this drill tap 20 and the drill tap 2 illustrated in FIG. 1 is as follows.

Conventional drill taps 2 have to have a relatively long shape, and because of the presence of the groove 10, the strength against bending stress is low and there is a high possibility of breakage.However, the present invention In the drill tap 20 according to the above, there is no stress concentration part like the groove 10, and the drill cutting edge and the tap cutting edge are formed parallel to each other, so the overall length of the drill tap 20 is As a result, the strength against bending stress is increased. Furthermore, like the drill tap 2 of the conventional example, the drill part 4 preceding the tap part 6
Since there is no need to drill holes in the workpiece, there is no problem that unnecessary holes communicating with the short holes are formed.

Furthermore, since short holes can be formed all at once,
This has the advantage of shortening the working time.

In addition, compared to the general operation of forming a short hole using a drill and a tap in sequence, the operation using the drill tap 20 is extremely simple and requires less time. , since the number of parts in the tool is small,
It goes without saying that daily maintenance and management of tools is easy.

Note that after forming a short hole by rotating the drill tap 20 in the direction of arrow A in the figure, the drill tap 20 will not come off from the short hole if a rotational force is applied in the opposite direction, that is, in the direction of arrow B. It will be easily understood.

Next, FIG. 5 shows another embodiment of the drill tap according to the present invention. In this case, the same reference numerals as in the previous embodiment indicate the same components.

In this embodiment, the inclination angles of the drill cutting edge 28a and the tap cutting edge 30a at the tip of the blade part 22a are θ1 and θ2, respectively.
Rather, the required clearance angle is secured by making the inclination angles θ1 and θ2 equal to form a smooth surface portion (see FIG. 6). Note that the tip portions of the blade portions 22b and 22c also form smooth surfaces similar to the blade portion 22a to obtain clearance angles.

With such a configuration, the tip of the drill tap can be formed more easily than in the embodiment described above, and the above-described functions and effects can be obtained without any reduction.

According to the present invention, it is possible to form short holes all at once with simple operations as described above, and as a result, production efficiency is greatly improved and various inconveniences of the conventional method can be eliminated. .

Although the present invention has been described above with reference to preferred embodiments, the present invention is not limited to these embodiments, and various improvements and changes in design are possible without departing from the gist of the present invention. Of course.

[Brief explanation of drawings]

1 is a side view of a drill tap according to the prior art, FIG. 2 is a side view of a drill tap according to the present invention, FIG. 3 is a partial end view of the tip of the drill tap shown in FIG. The figure is a schematic cross-sectional view taken along the line IV-IV in FIG. 3, and FIG. 5 is a partial end view of the tip part showing another embodiment of the drill tap according to the present invention.
6 is a schematic cross-sectional view taken along the line VI-Vl in FIG. 5. FIG. 20...Drill tap 22a-22c...Blade portion 24...Handle portion 28a-28c...Drill cutting edge 30a-30c...Tap cutting edge 32a-32c...Land

Claims (4)

[Claims] (1) In a drill tap having a handle portion and a plurality of spirally extending blade portions, the drill cutting edge and the tap cutting edge are spaced apart from each other by a predetermined distance on the same land constituting each of the blade portions to form a spiral shape. What is claimed is: 1. A drill tap, characterized in that the drill cutting edge is located forward in the cutting rotation direction with respect to the tap cutting edge. (2) A drill tap according to claim 1, in which a clearance groove for discharging cutting waste to the outside is defined between the drill cutting edge and the tap cutting edge constituting the blade part. . (3) In the drill tap according to claim 1, the relief groove defined between the drill cutting edge and the tap cutting edge is located immediately before the drill cutting edge with respect to the cutting rotation direction of the drill tap. A drill tap in which the depth of the first relief groove provided in the tap is selected to be greater than that of the second relief groove provided immediately before the tap cutting edge. (4) The drill tap according to claim 1, wherein the surface portion at the tip of each of the drill cutting edge and the tap cutting edge is an inclined surface defining a clearance angle.