KR20170021520A - Spiral Plute Tap - Google Patents

Abstract

A spiral plute tap is disclosed. According to the present invention, in the spiral plute tap, a relief surface of a chamfer is formed with a compound shape instead of one Archimedes spiral shape to give a relief size around a heel to be smaller than in case of extending with an Archimedes spiral. Therefore, when the tap is reversely rotated, destruction of a drawn wire of the chamfer caused by a chip which is not separated from a base material can be minimized.

Description

Spiral Plute Tap < RTI ID = 0.0 >

The present invention relates to a spiral flute tab which minimizes the breakage of the engaging portion due to a chip during reverse rotation of the tab in the process of cutting a blind hole by forming the relief surface of the engaging portion into a composite shape other than an Archimedean waved shape.

The tab is a rotary cutting tool mainly for machining a female thread on a metal product or part, and is a cylindrical or conical thread cutting tool having a thread-like cutting element on the outer periphery. The tab can be moved in the axial direction at the same time as the tab is rotated to cut the groove that is the same as the thread of the tab while making a hole in the work base material. When the axial advance reaches a predetermined position, it retracts in the axial direction simultaneously with the reverse rotation, thereby returning out of the base material to terminate the tapping cycle.

When the tabs are classified according to the shape of the flute serving as the discharge path of the chip in the cutting process, there are a straight plute tap in which the flute is straight and a spiral plute tap in which the flute is in a spiral shape . Straight flute taps are suitable for materials that generate short chips such as cast iron. Chips separated from the base material during tapping are housed in a flute. On the other hand, the spiral flute taps generally generate long chips, and the chips are ejected along the flutes during tapping. Therefore, the spiral flute tab can be applied to any of a through hole and a blind hole.

Fig. 1 is a view showing a structure of a spiral flute tab, and Fig. 2 is a cross-sectional view of a conventional swaging flute tab.

1, the tab has a body 11 formed with a thread on the axial end 14 side and a cylindrical shank 16 on the rear end 19 connected to the body 11, , And a round bar as a whole.

A flute 12 and a threaded land 13 are arranged in a spiral arrangement in an alternating manner along the body 11 to discharge the chip 23 to the body 11. Because the flutes 12 are arranged spirally, the tabs in Fig. 1 are spiral flute taps. The flute 12 serves not only to discharge the chips separated from the blank base material 20 during the cutting process, but also to determine the shape of the cutting edge 41.

On the other hand, the body 11 is divided into a chamfer 15 disposed on the tip end side and a full threaded portion 17 connected to the engaging portion 15 and guiding the forward and backward movement of the tab. The full threaded portion 17 does not perform a cutting action.

The engaging portion 15 has a conical shape in which the height of the thread is lowered toward the front end and a relief face 15 having a sheath 41 and a heel 46 at the periphery of the land 13 of the engaging portion 15 40 are formed. When the tab proceeds in the axial direction with rotation, the cutting edge 40 of the land 13 scrapes the base material 20 and the thread formed in the land 30 creates a female thread along the inner surface of the hole. The arrows in Fig. 2 indicate the direction of rotation of the tab when the tab is advanced for cutting.

2, the reliefs 48 and 49, which indicate the degree of separation (or the amount of separation) between the relief surface 40 and the base material 20, are defined by the rake angle 43 A proper wedge angle 45 is formed in the cutting edge 40 so that the cutting edge 20 can be easily cut while maintaining the cutting edge strength and the elastic recovery of the cutting base 20 Spring back) Lowering the pressure on the tab. Of course, the size of the relief 48, 49 also affects the ease of cutting and the strength of the wire. If the reliefs 48 and 49 are large, the wedge angle 45 becomes small, the blade becomes sharp and the strength decreases, but the compression of the tabs due to elastic recovery is reduced. Of course, if the reliefs 48 and 49 are small, the opposite phenomenon occurs. Therefore, the sizes of the reliefs 48 and 49 are differently applied depending on the properties of the base material 47 and other conditions.

The conventional relief surface 40 shown in FIG. 2 is of the Spiral of Archimedes in which the radius 44 from the shaft 18 gradually decreases linearly from the cutting edge 41 to the heel 46 Shape. Thus, the radius of the wire 41 is the maximum and the radius of the heel 46 is the minimum. In other words, the relief 48 (or the relief amount thereof) at the heel 46 is the largest, and the relief becomes larger as the heel 46 approaches the relief 48 (or the relief amount thereof) .

The problem is that when cutting a so-called " clogged hole ", in which the tab does not penetrate the base material but only pierces to a certain depth, a chip is formed that is not completely separated from the base material, So that the wire 41 can be broken or destroyed. If the tab forms the through hole in the base material 20, since the chip is completely separated from the base material 20 because the tab engagement portion 15 is rotated in the reverse direction after passing completely through the hole, Disability rarely occurs.

FIG. 3 is a view showing a process of cutting a blind hole using the spiral flute tab of FIG. 2. FIG. 3 (a), as the tab advances with rotation, the chip 23, which has been separated from the base material 20 by the cutting edge 41, is completely separated from the base material 20 even after the progress of the tab is completed And it remains.

3 (b) and Fig. 3 (c), the relief 49 (Fig. 3 (b) and Fig. 3 The chips 23 that are not separated from the workpiece base material 20 are sandwiched between the relief surface 40 and the workpiece base material 20 because the chips 23 are sufficient to interfere with the chip 23. As the reverse rotation progresses, the amount of relief gradually decreases, and the chip that is sandwiched between the chips further presses the tab.

As the reverse rotation further proceeds, the lead wire 41 rushes over the chip 23 by the reverse rotation of the tab, and the lead wire 41 is broken or broken by the chip 23. Particularly, if the chip 23 is severely separated or wound at the time of cutting, the degree of breakage of the cutting edge 41 is increased.

When the hole to be processed is not a through hole and the relatively long chip 23 is not completely separated from the workpiece base 20 in the case where the workpiece base 20 is a ductile material or a tough material Reverse rotation occurs in this state, and in this case, the damage of the tab may become larger.

It is an object of the present invention to provide a spiral flute tap which minimizes the breakage of the engaging portion due to the chip during the reverse rotation of the tab in the process of cutting the blind hole by molding the relief surface of the engaging portion into a composite shape other than the Archimedes wavy line shape. .

According to an aspect of the present invention, there is provided a spiral flute tap including a relief surface extending from a first end to a heel and extending from a first end to a heel. At this time, the size of the relief at the heel is set to be smaller than the imaginary relief at the heel when the line applied between the lead and the first point extends to the heel.

As a first example, the relief surface from the lead line to the first point may have an arcymedesian waveness shape, and the relief surface from the first point to the heel may have an arc shape having the same radius as the center axis of the tab .

As a second example, the relief surface from the incline to the first point has an Archimedean waveness shape, the relief surface from the first point to the heel includes a first virtual line extending from the Archimedes waveline to the heel, It can be formed in a curved shape formed between the arc shapes having the same radius from the central axis of the tab.

As a third example, the relief surface from the incline to the first point has an Archimedes spiral shape, and extends from the first point to the second point located on the relief surface and from the second point to the heel, It can be formed in a curved shape.

As a fourth example, the relief surface from the cutting edge to the first point may have an archimedean wavy line shape, and the relief surface from the first point to the heel may be formed in a straight line shape.

As a fifth example, a relief surface extending from the cutting edge to the heel may be formed in a straight line passing through the first point.

As a sixth example, a relief surface extending from the cutting line to the heel is formed in a shape in which the plurality of straight lines extend, and the first point is formed on one straight line of the plurality of straight lines, It can be an intersection of straight lines.

In the above example, it is preferable that the first point is set at a position where the rotation angle rotated from the cutter is 5 degrees or more with respect to the central axis of the tab, thereby sufficiently securing the relief in the vicinity of the cutter.

The spiral flute taps of the present invention are provided with a smaller relief size in the vicinity of the heel in the formation of the relief surface than in the conventional case where the relief is extended by the Archimedes waved line. This allows (1) a sufficient relief near the cutting edge to maintain sufficient cutting performance, (2) the relief at the heel is relatively small so that chips not separated from the workpiece during the reverse rotation are not caught in the relief The chip can be removed at the same time.

1 is a view showing a structure of a spiral flute tab,
FIG. 2 is a cross-sectional view of the engaging portion illustrating the relief structure of the engaging portion of the conventional spiral flute tab,
Fig. 3 is a cross-sectional view of the engaging portion showing an example of a process of cutting the clogged hole of the spiral flute tab of Fig. 2,
4 is a cross-sectional view illustrating a relief structure of a spiral flute tap according to an embodiment of the present invention,
5 is a cross-sectional view illustrating a relief structure of a spiral flute tab according to another embodiment of the present invention,
6 is a cross-sectional view of the engaging portion illustrating an example of the process of cutting the clogged hole of the spiral flute tab of Fig. 4, and Fig.
7 and 8 are cross-sectional views illustrating a relief structure of a spiral flute tab according to another embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail with reference to the drawings.

The overall shape and structure of the spiral flute taps of the present invention are basically the same as those shown in Fig.

The tab of the present invention has a body 11 screwed around the axial end 14 and a cylindrical shank 16 on the rear end 19 adjoining the body 11, Shape. A plurality of flutes (12) and a plurality of lands (13) are arranged in a spiral shape in an alternating manner on the body (11). The tabs exemplarily shown in Figs. 1 to 8 are examples in which three flutes 12 and three lands 13 are spirally arranged, but the present invention is not limited thereto, and the number of flutes and lands may vary .

The body (11) is provided with the engaging portion (15) and the full threaded portion (17). However, as described below with reference to Figs. 4 and 5, the tab of the present invention differs from that of a conventional relief surface in the engaging portion 15. Figs. 4 and 5 show cross-sections of the engaging portion 15 and the base material 20 when the tab is advanced while rotating for cutting, and arrows indicate the rotation of the tab when the tab is advanced for cutting Direction.

Referring to FIGS. 4 and 5, relief surfaces 140 and 240 having tines 141 and 241 and heels 146 and 246 are formed on the periphery of the land 13, do. When the tab proceeds in the axial direction together with the rotation, the land 13 cuts the female thread along the hole of the base material 20.

However, the present invention forms the relief surfaces 140 and 240 differently from the relief surface 40 of the conventional tab.

First, an arbitrary first point (A) is set between the curved line and the heel, and the curved line or the straight line is formed between the curved line and the first point (A) so as to increase the relief gradually. However, the relief at the heel is set to be smaller than the imaginary relief size when the line (Archimedes, curves or straight lines) applied from the lead to the first point (A) is extended to the heel. (2) the chip 23, which has not been completely separated from the base material 20 during the reverse rotation, is prevented from being caught in the relief and is completely separated from the base material 20 So that the chip 23 can be removed. Here, it is preferable that the first point (A) is located at a position where the rotation angle rotated from the cutting edge with respect to the center axis of the tab is 5 degrees or more, thereby securing the cutting performance in the cutting edge.

To this end, the relief surface of the present invention is not formed by one Archimedean curve as in the conventional relief surface 40 shown in FIG. 2, but formed by a plurality of curves having different properties (curvature changes) A combination of a curve and a straight line, or a combination of a straight line or a plurality of straight lines Can be configured. Hereinafter, an example will be described.

≪ Embodiment 1: Fig. 4 &

4 is an example in which the relief surface 140 is formed by two curved lines having different curvature changes.

4, (1) the relief surface 140 from the gland 141 to the arbitrary first point A is shaped in the Archimedes waved shape (i.e., the size of the relief increases with the rotation angle) By providing a suitable relief, it is designed to ensure ease of cutting and to eliminate problems due to elastic recovery. Here, the reference numeral 148 in Fig. 4 represents the relief at the first point (A), and the relief 148 at the first point (A) and the first point is the property of the material of the base material, Etc., can be determined by a conventional method,

(2) However, the relief surface 140 from the first point (A) to the heel 146 is formed as one arc having the same radius from the axis 118. Here, the first point A is located at a position where the rotation angle 142 rotated from the trunk 141 is 5 degrees or more with respect to the center axis 118 of the tab.

The cutting operation of the tab of Fig. 4 will be described with reference to Fig. 6 (a), the size 148 of the relief in the vicinity of the cutting edge 141 (from the cutting edge to the first point) ensures a good cutting performance by forming a suitable wedge angle 145 By designing to a sufficient degree to eliminate the problem due to elastic recovery, there is no problem in cutting the tabs of the base material 20.

6 (b) and 6 (c) in the state where chips 23 not completely separated from the base material 20 are generated, the size of the relief in the vicinity of the heel 146 The chip 23 is not caught deeply in the relief and the chip 23 is separated from the base material 20 by the heel 146 while the reverse rotation further proceeds. Therefore, the tabs can be smoothly reversed without causing the breakage of the cutter 141.

≪ Embodiment 2: Fig. 5 &

5 is an example in which the relief surface 240 is formed by two curved lines having different curvature changes.

5, (1) the relief surface 240 from the gland 241 to the first point A is formed by increasing the size of the relief according to the rotation angle as in the example of FIG. 4, So that the ease of cutting is ensured and the problem of elastic recovery is eliminated.

The relief surface 240 from the first point A to the heel 246 has an arc R2 equal in radius 244 as shown in Figure 4 and a virtual arc R2 extending from the Archimedean line to the heel, And a curve R1 formed between the lines R3. Referring to FIG. 5, it can be seen that the size 259 of the relief at the heel 246 is shown larger than the size 159 of the corresponding relief in FIG. Likewise, the first point A in the example of FIG. 5 is preferably at a position of 5 degrees or more in the magnitude of the rotation angle 242, such as the first point A in the example of FIG. In Fig. 5, 248 represents the relief of the first point (A).

4 and 5 are designed such that the curvatures of the relief planes 140 and 240 vary with respect to the first point A as a whole.

On the other hand, according to another embodiment, the relief surface may be formed into a curved shape in which the curvature changes with respect to two points (the first point and the second point on the relief surface).

≪ Embodiment 3: Figs. 7 and 8 &

7 shows an example in which the relief surface 340 is formed by one straight line passing an arbitrary first point A and FIG. 8 is an example in which the relief surface 440 is formed by extending a plurality of straight lines . Figs. 7 and 8 show a cross section of the engaging portion 15 and the base material 20 when the tab is advanced while rotating for cutting. The arrow indicates the direction of rotation of the tab when the tab is advanced for cutting .

7, since the relief surface 340 is one straight line, the size 348 of the relief of the first point A becomes larger than the maximum value 348 as the relief gradually increases from the lead 341 to the first point A. [ And the relief becomes smaller again as it goes from the first point A to the heel 346.

8 is an example in which the relief surface 440 is formed by three straight lines. The relief surface 440 is straightly formed from the cutting edge 441 to the first point A and the relief surface 440 from the first point A to the second point B is also straight, The relief surface 440 from the second point B to the heel 446 is also formed as a straight line. The first point (A) in the example of FIG. 8 is also preferably at a position where the size of the rotation angle 242 is 5 degrees or more. 8, when the relief surface is designed by extending a plurality of straight lines, the first point A may be arranged at an intersection of two straight lines included in a plurality of straight lines as shown in FIG. 8, Or may be formed on one straight line.

Here, in the example of FIG. 8, the first point A, the second point B, and the heel 446 are shown as being located at the same distance from the axis 418, but need not be limited thereto.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be construed as limiting the scope of the invention as defined by the appended claims. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention.

11: body 12; flute
13: Land 15:
16: shank 17: full thread
18, 118, 218: central axis of the tab 19:
20: Pitch base material 23: Chip
140, 240 Relief surface 141, 241:
142, 242: rotation angle 143, 243: rake angle
144, 244: Radius 145, 245: Wedge angle
146, 246: Heel
148, 248: Relief in the vicinity of the bridle,
159, 259: Relief near the heel

Claims (8)

In the spiral flute tab,
And a relief surface extending from the wire through the first point to the heel,
Wherein the size of the relief at the heel is smaller than the imaginary relief at the heel when a line applied between the lead and the first point extends to the heel.
The method according to claim 1,
Wherein the relief surface from the first to the first point has an arcymedesian waved shape and the relief surface from the first point to the heel has an arc shape having the same radius as the center axis of the tab.
The method according to claim 1,
Wherein the relief surface from the first to the first point has an Archimedean waveness shape,
Wherein the relief surface from the first point to the heel is a curved shape formed between a virtual line extending to the heel of the Archimedes waveline and an arc shape having the same radius from the central axis of the tab.
The method according to claim 1,
Wherein the relief surface from the first to the first point has an archimedean waveness shape and has a curved shape with different curvatures from the first point to the second point located on the relief surface and from the second point to the heel Spiral flute tab with.
The method according to claim 1,
Wherein the relief surface from the first to the first point has an Archimedean wavy shape and the relief surface from the first point to the heel has a straight shape.
The method according to claim 1,
And a relief surface extending from the cutting edge to the heel is formed in a straight line passing through the first point.
The method according to claim 1,
Wherein the relief surface extending from the cutting edge to the heel is formed in a shape in which a plurality of straight lines extend, and the first point is formed on one straight line of the plurality of straight lines or an intersection point of two straight lines included in the plurality of straight lines Features a spiral flute tab.
8. The method according to any one of claims 2 to 7,
Wherein the first point is set at a position where the rotation angle rotated from the cutter is 5 degrees or more with respect to the central axis of the tab to secure a relief in the vicinity of the cutter.

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