Tap with oil hole

Abstract

To provide a tap with an oil hole capable of effectively supplying machining oil.SOLUTION: A tap with an oil hole 1 includes a shank 2, a thread portion 4 having a chamfer portion 6 and a complete thread portion 7, a plurality of groove portions 5 provided in a longitudinal direction so as to divide the thread portion 4, a supply hole 10 provided along an axial center from an end surface of the shank 2, and at least one ejection hole 11 branched from the supply hole 10 in a direction orthogonal to the axial center and provided in the plurality of groove portions 5.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a tap with an oil hole. [Background technology]

[0002] Oil-hole taps are known as tools for forming internal threads in workpieces. Oil-hole taps have a supply hole extending from the end face of the shank along the axis and a discharge hole branching off from the supply hole. In oil-hole taps, machining oil is supplied through the supply hole and then discharged into the pilot hole in the workpiece via the discharge hole. The oil penetrates between the oil-hole tap and the wall of the pilot hole, suppressing heat generation during internal thread machining and reducing frictional resistance between the workpiece and the oil-hole tap, thereby extending the tool life of the oil-hole tap.

[0003] A known example of a tap with an oil hole is the thread forming tap described in Patent Document 1. Generally, with a thread forming tap, a helical-shaped threaded portion is rotated on a workpiece in which a pilot hole has been drilled, gradually penetrating the pilot hole and plastically deforming the pilot hole portion, thereby forming an internal thread. This requires a greater force than forming an internal thread by cutting, resulting in greater heat generation and frictional resistance, making it important to provide an appropriate supply of processing oil. Another known example of a tap with an oil hole is the cutting tap described in Patent Document 2.

[0004] The thread forming tap described in Patent Document 1 has a supply hole provided from the end face of the shank along the axis and ejection holes branching from the supply hole in a direction perpendicular to the axis, i.e., radially outward. The cutting tap described in Patent Document 2 has a supply hole provided from the end face of the shank along the axis and ejection holes branching from the supply hole diagonally forward. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Special Publication No. 40-1748 [Patent Document 2] Japanese Utility Model Application Publication No. 5-49216 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the thread forming taps described in Patent Documents 1 and 2, the arrangement and orientation of the ejection holes in the axial direction are not taken into consideration in detail, and therefore there is room for improvement in terms of stable internal thread machining and, ultimately, extending the life of the tap.

[0007] An object of the present invention is to provide a tap with an oil hole that can effectively supply machining oil. [Means for solving the problem]

[0008] According to one aspect of the present invention, there is provided a tap with an oil hole comprising a shank, a threaded portion having a lead portion and a full thread portion, a plurality of grooves arranged in the longitudinal direction so as to divide the threaded portion, a supply hole arranged from the end face of the shank along the axis, and at least one ejection hole branching from the supply hole in a direction perpendicular to the axis and arranged within the plurality of grooves, wherein the at least one ejection hole is arranged along the thread of the full thread portion.

[0009] It is preferable that the at least one ejection hole is arranged along a first complete crest of the complete crest portion.It is preferable that the at least one ejection hole includes at least two ejection holes, and at least one of the at least two ejection holes is not arranged along the first complete crest.It is preferable that the at least two ejection holes are arranged within a range of one pitch in the front-rear direction from the first complete crest. [Effects of the Invention]

[0010] According to the aspects of the present invention, a common effect is achieved in that a tap with an oil hole capable of effectively supplying machining oil is provided. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a perspective view of a tap with an oil hole according to an embodiment of the present invention. [Figure 2] FIG. 2 is a side cross-sectional view of the tap with an oil hole. [Figure 3] FIG. 3 is a front view of the tap with an oil hole. [Figure 4] FIG. 4 is an enlarged side view of the processing portion of the oil-hole tap. [Figure 5] FIG. 5 is another enlarged side view of the working portion of the oil-hole tap. [Figure 6] FIG. 6 is a photograph of the surface of a thread forming tap after machining using the thread forming tap according to the embodiment of the present invention. [Figure 7] FIG. 7 is a photograph of the surface of a thread forming tap after machining using the thread forming tap according to the comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Corresponding components throughout the drawings are designated by common reference numerals.

[0013] Fig. 1 is a perspective view of a tap 1 with an oil hole according to an embodiment of the present invention, Fig. 2 is a side view of the tap 1 with an oil hole, Fig. 3 is a front view of the tap 1 with an oil hole, and Fig. 4 is an enlarged side view of the working portion 3 of the tap 1 with an oil hole. The illustrated tap 1 with an oil hole according to the embodiment of the present invention is a forming tap, but it may also be a cutting tap.

[0014] The oil-hole tap 1 has a shank 2 and a machining portion 3. The oil-hole tap 1 is attached to the spindle of a processing machine by holding the shank 2 in a chuck. In this specification, in the axial direction of the oil-hole tap 1, the side facing the machining portion 3 is defined as the "front" side, and the side opposite the machining portion 3 is defined as the "rear" side.

[0015] The processing portion 3 has a threaded portion 4 formed in a helical shape and a plurality of grooves 5 arranged in the longitudinal direction so as to divide the threaded portion 4. Each of the grooves 5 is parallel to the axis of the oil-hole tap 1. The plurality of grooves 5 is, for example, eight grooves 5, but may also be two, three, or another number of grooves 5. The plurality of grooves 5 are arranged at equal intervals along the circumferential direction.

[0016] The thread portion 4 has a chamfer 6 and a full thread portion 7 arranged continuously behind the chamfer 6. The chamfer 6 is tapered and serves as a guide for the oil-hole tap 1 to enter a pilot hole in a workpiece machined with a drill or the like. That is, the outer diameter of the thread at the tip of the chamfer 6 is formed smaller than the inner diameter of the pilot hole. The outer diameter and effective diameter of the thread of the chamfer 6 gradually increase from the tip along the lead, and are formed to match the root diameter of the specified internal thread. The length of the chamfer 6 is 2 to 4 threads. In the oil-hole tap 1, when the chamfer 6 is screwed into the pilot hole, the metal structure of the pilot hole is gradually crushed and plastically deformed, raising the inner surface of the pilot hole and forming an internal thread.

[0017] As shown in Figure 4, the thread located at the tip of the full thread portion 7 adjacent to the chamfer 6 is referred to as the first full thread 71, and the thread adjacent to the first full thread 71 is referred to as the second full thread 72. In addition, the thread located at the rear end of the chamfer 6 adjacent to the first full thread 71 of the full thread portion 7 is referred to as the final chamfer 61.

[0018] The oil-hole tap 1 has a supply hole 10 extending from the end face of the shank 2 along the axis to the inside of the threaded portion 4. A plurality of ejection holes 11 are provided branching from the supply hole 10 in a direction perpendicular to the axis, i.e., radially outward. The openings of each of the ejection holes 11 are located within the grooves 5. Machining oil supplied from a processing machine to which the oil-hole tap 1 is attached is supplied from the end face of the shank 2 into the supply hole 10 and ejected through the ejection holes 11 in a direction perpendicular to the axis. The plurality of ejection holes 11 are, for example, eight, and are arranged within the corresponding grooves 5. However, the number of ejection holes 11 may be at least one, or may be any other number, such as two or four. The plurality of ejection holes 11 are preferably arranged symmetrically with respect to the axis of the oil-hole tap 1 to balance the ejection of the machining oil.

[0019] The multiple ejection holes 11 are arranged along one lead of the thread of the complete thread portion 7, specifically along the first complete thread 71. In more detail, the thread is formed in a helical shape and is divided by groove portions 5, and each of the eight ejection holes 11 is arranged in a groove portion 5 in a corresponding portion of the divided first complete thread 71. Therefore, adjacent ejection holes 11 are arranged at positions offset from each other in the axial direction along the thread.

[0020] Referring to Figure 3, of the eight nozzle holes 11 provided in the oil-hole tap 1, the nozzle hole 11 located furthest forward, i.e., the nozzle hole 11 located at the very tip of the first complete ridge 71, is designated as the first nozzle hole 11A, and the nozzle holes 11 located 90 degrees, 180 degrees, and 270 degrees offset from the first nozzle hole 11A in the rotational direction are designated as the second nozzle hole 11B, the third nozzle hole 11C, and the fourth nozzle hole 11D, respectively.

[0021] FIG. 5 is another enlarged side view of the machining portion 3 of the oil-hole tap 1. Referring to FIG. 5 in addition to FIG. 3, FIG. 5(A) is a side view of the machining portion 3 facing the first nozzle hole 11A, FIG. 5(B) is a side view of the machining portion 3 facing the second nozzle hole 11B, FIG. 5(C) is a side view of the machining portion 3 facing the third nozzle hole 11C, and FIG. 5(D) is a side view of the machining portion 3 facing the fourth nozzle hole 11D. In FIGS. 5(A) to 5(D), a reference line R is drawn from the tip of the oil-hole tap 1 to the machining portion 3 at an equal position. The reference line R indicates the axial position of the starting point of the first complete ridge 71 in FIG. 5(A). As shown in FIG. 5(A), the reference line R passes through approximately the center of the first nozzle hole 11A. The second nozzle hole 11B shown in Fig. 5(B) is located at a position rotated 90 degrees from the position of the first nozzle hole 11A, and is therefore offset rearward by ¼ of one pitch in the axial direction relative to the first nozzle hole 11A. Similarly, the third nozzle hole 11C shown in Fig. 5(C) is located at a position rotated 180 degrees from the position of the first nozzle hole 11A, and is therefore offset rearward by ½ of one pitch in the axial direction relative to the first nozzle hole 11A. The fourth nozzle hole 11D shown in Fig. 5(D) is located at a position rotated 270 degrees from the position of the first nozzle hole 11A, and is therefore offset rearward by ¾ of one pitch in the axial direction relative to the first nozzle hole 11A.

[0022] According to the oil-hole tap 1, machining oil is ejected through the ejection holes 11 in a direction perpendicular to the axis. The machining oil ejected from the ejection holes 11 collides with the inner wall of the pilot hole and is dispersed in the front-to-back direction. As a result, machining oil can be supplied more evenly within the pilot hole during internal thread drilling using the oil-hole tap 1. Specifically, because the ejection holes 11 are arranged along the first complete thread 71, the ejected machining oil collides with the root of the internal thread being formed by the first complete thread 71 and flows along the flank surfaces, which are the slopes of the thread of the internal thread being formed, before and after that. As a result, machining oil can be supplied evenly in the front-to-back direction with the first complete thread 71 as the boundary, i.e., in both the chamfer portion 6 and the complete thread portion 7.

[0023] The first complete thread 71 of the full thread portion 7 is also the transition portion from the tapered chamfering portion 6, and therefore receives the greatest force when machining the internal thread. In particular, the first complete thread 71 is formed with the largest outer diameter, albeit slightly, in the thread portion 4, i.e., in the complete thread portion 7. Therefore, when machining the internal thread, the frictional resistance applied to the first complete thread 71, particularly the flank surface of the first complete thread 71 on the chamfering portion 6 side, is the greatest. Therefore, by ejecting machining oil from the ejection holes 11 arranged along the first complete thread 71 and supplying the machining oil in the front-to-rear direction of the first complete thread 71, stable internal thread machining can be achieved, and the effects of reducing frictional resistance and heat generation and extending tool life can be maximized.

[0024] Fig. 6 is a photograph of the surface of a thread forming tap after processing using a thread forming tap 100 according to an embodiment of the present invention, and Fig. 7 is a photograph of the surface of a thread forming tap after processing using a thread forming tap 200 according to a comparative example. Figs. 6 and 7 are photographs of the thread forming tap viewed from diagonally above the front.

[0025] The thread forming tap 100 shown in FIG. 6 has a threaded portion 104 and a groove portion 105 provided to separate the threaded portion 104. The threaded portion 104 has a first complete thread 171 and a second complete thread 172 in the full thread portion, and a final chamfer thread 161 in the chamfer portion. An ejection hole 111 is arranged in the groove portion 105 along the first complete thread 171. Similarly, the thread forming tap 200 shown in FIG. 7 has a threaded portion 204 and a groove portion 205 provided to separate the threaded portion 204. The threaded portion 204 has a first complete thread 271 and a second complete thread 272 in the full thread portion, and a final chamfer thread 261 in the chamfer portion. An ejection hole 211 is arranged in the groove portion 205 forward of the first complete thread 271. The ejection hole 211 is an ejection hole branching off from the supply hole in a direction perpendicular to the axis. That is, the thread forming tap 100 and the thread forming tap 200 differ only in the arrangement of the ejection holes.

[0026] Referring to the photograph of the surface of the thread forming tap 100 after machining shown in Figure 6, no noticeable scratches or the like are visible on the surface of the thread portion 104. Therefore, it can be said that machining oil was effectively supplied with the thread forming tap 100. On the other hand, referring to the photograph of the surface of the thread forming tap 200 after machining shown in Figure 7, scraping marks F have occurred on the flank surfaces of the first complete thread 271 and the second complete thread 272. Therefore, it can be said that with the thread forming tap 200, machining oil was not adequately supplied to the first complete thread 271, which has particularly high frictional resistance, as described above, and the surface of the thread forming tap 200 was damaged by friction and heat.

[0027] As described above, according to the embodiment of the present invention, it is possible to provide a tap with an oil hole 1 that can effectively supply machining oil. Because the tap with an oil hole 1 sprays machining oil radially outward, it can be used whether the pilot hole in the workpiece is a through hole or a blind hole.

[0028] The tap 1 with oil hole may have at least one ejection hole 11. Preferably, the at least one ejection hole 11 is arranged along the first complete thread 71, but it may also be arranged along a thread of a complete thread portion 7 other than the first complete thread 71. By arranging the ejection hole 11 along the thread of the complete thread portion 7, as described above, the ejected machining oil collides with the root of the female thread being formed. As a result, the oil flows before and after that along the flank surfaces, which are the slopes of the thread of the female thread being formed, making it possible to supply the machining oil evenly.

[0029] When at least two ejection holes 11 are provided, at least one of the at least two ejection holes 11 does not have to be arranged along the first complete crest 71. In this case, it is preferable that the at least two ejection holes 11 are arranged within a range of one pitch in the front-to-rear direction from the first complete crest 71, that is, between the final cutting edge crest 61 and the second complete crest 72. Specifically, the at least two ejection holes 11 may be arranged only between the final cutting edge crest 61 and the first complete crest 71, or only between the first complete crest 71 and the second complete crest 72. By arranging the ejection holes 11 at least between the final cutting edge crest 61 and the second complete crest 72, it becomes possible to supply machining oil to the first complete crest 71, which is most likely to be damaged. [Explanation of symbols]

[0030] 1 tap 2 shanks 3 Processing section 4 Threaded section 5 Groove 6. Feeding section 7 Completely Mountainous 10 Supply hole 11 Spout hole 61 Last Meal Mountain 71 1st complete mountain 72 Second complete mountain

Claims

1. Shank and a threaded portion having a chamfer and a full thread; a plurality of grooves provided in the longitudinal direction so as to divide the threaded portion; a supply hole provided along the axis from the end face of the shank; at least one ejection hole branching from the supply hole in a direction perpendicular to the axis and provided in the plurality of grooves; The tap with oil hole, wherein the at least one ejection hole is arranged along the thread of the fully threaded portion.

2. The tap with an oil hole according to claim 1 , wherein the at least one ejection hole is arranged along a first full thread of the full thread portion.

3. the at least one orifice includes at least two of the orifices; The tap with an oil hole according to claim 2 , wherein at least one of the at least two ejection holes is not disposed along the first complete ridge.

4. 4. The tap with an oil hole according to claim 3, wherein the at least two ejection holes are arranged within a range of one pitch in the front-rear direction from the first complete ridge.

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