JP3103239B2 - Spiral tap - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spiral tap for machining a female screw.

[0002]

2. Description of the Related Art A twist groove tap having a chip discharge groove twisted in the same direction as a screw has a function of discharging chips generated during cutting to the shank side of the tap along the twist groove. Therefore, there is an advantage that no chips remain inside the female screw when the tapping is performed in the blind hole, and there is no need to remove the chips inside.

[0003] However, in such a tap having a groove twisted in the same direction as the screw, due to the reaction force of the chip discharging action of the twisted groove, the tap is advanced by a lead larger than a regular screw lead during cutting. Such force is generated, and the phenomenon of tap advance is likely to occur, as a result,
The cross-sectional shape of the thread of the cut female screw tends to be smaller than the regular cross-sectional shape.

A twisted groove tap having a chip discharging groove twisted in the opposite direction to the screw has a function of discharging chips generated during cutting to the bite side of the tap along the twisted groove. Therefore, there is an advantage that the chips are less likely to cause an obstacle when tapping.

However, in a tap having a groove twisted in the direction opposite to the screw, a reaction force of the chip discharging action generates a force to push the tap back in the opposite direction of the tapping direction, and the cutting force is generated during cutting. A delay phenomenon occurs in which the lead becomes smaller than the lead of the regular screw. Therefore, the cross-sectional shape of the thread of the cut female screw tends to be smaller than the regular cross-sectional shape.

In order to make the above phenomenon difficult to occur, in a tap having a chip discharging groove twisted in the same direction as the screw, a relief which is a basic of a cutting tool, that is, a second cut on a flank face of the screw is used. There is a method to fit the lead of the regular screw without attaching it.In addition, in the tapping work, the tap feed amount is made smaller than the regular feed amount in consideration of the phenomenon of excessive progress, and the tapping method is used. Generally done. In the tap having a groove for discharging chips which is twisted in the opposite direction to the screw, measures such as increasing the feed rate in consideration of a delay phenomenon in the tapping operation have been taken.

[0007]

However, in a tap having a chip discharging groove twisted in the same direction as the screw, a relief, which is the basis of the cutting tool, that is, a second cut on the flank face of the screw is not provided. However, the method of fitting the lead of a regular screw has a problem that the cutting resistance is large and welding is easily generated on the thread surface of the tap. or,
The method of tapping with the tap feed amount smaller than the regular feed amount in anticipation of the phenomenon of excessive progress in the tapping work involves variations in the accuracy of the female screw cut due to the tension of the tapping holder used and the tapping conditions. In addition, if the tapping operation of a tap with a chip discharge groove twisted in the opposite direction to the screw is set at a high feed in anticipation of a delay phenomenon, the accuracy of the cut internal thread will vary. There is a problem that the possibility of occurrence of defective products is high.

[0008]

According to the present invention, there is provided a cutting tap having a chip discharging groove twisted in the same direction as a screw. An imaginary cylinder in which both the flank of the negative flank and the flank of the lateral rake angle are positive and the flank is secondly cut from the cutting edge, and the width of the thread groove is equal to the width of the thread. The flank face where the side rake angle between the imaginary cylinder and the bottom of the screw is positive is a regular screw lead, and the width of the thread groove of the thread is equal to the width of the thread. A spiral tap is formed by applying a negative lead to a normal screw lead within the range of the flank where the side rake angle between the virtual cylinder and the virtual cylinder in contact with the screw crest is positive. I do.

Further, in a cutting tap having a chip discharging groove twisted in a direction opposite to a screw, a flank face having a negative lateral rake angle and a flank face having a positive lateral rake angle in a thread of a thread portion. A side rake angle between a virtual cylinder in which both flank surfaces are secondly cut from the cutting edge and the width of the thread groove is equal to the width of the thread and the virtual cylinder in contact with the root of the screw. The flank surface where is positive is the regular screw lead, the virtual cylinder whose screw groove width is equal to the width of the screw thread and the virtual cylinder in contact with the top of the screw thread The spiral tap is formed by applying a positive lead to a regular screw lead within the range of the flank surface where the lateral rake angle becomes positive between.

[0010]

According to the present invention, as described above, the two flanks of the torsion groove tap are secondly cut from the cutting edge, and in a tap having a groove twisted in the same direction as the screw, the thread groove of the screw portion is formed. Of a regular screw only in the range of the flank where the lateral rake angle between the virtual cylinder whose width is equal to the width of the thread and the virtual cylinder touching the crest of the thread is positive. For cutting taps that have a negative lead to the lead and have a chip discharge groove twisted in the opposite direction to the screw, a hypothetical such that the width of the thread groove of the thread is equal to the width of the thread By applying a positive lead to a regular screw lead only within the range of the flank where the lateral rake angle between the perfect cylinder and the virtual cylinder in contact with the top of the screw thread is different, Raw when cutting in That proceed it is possible to measure the prevention of excessive phenomenon or delay phenomenon.

By providing a lead that is negative with respect to the normal lead only within the above-described range and a lead that is positive only within the above-described range, the most important bit in the tap cutting mechanism can be reduced. The positive and negative leads described above do not exist in the first peak, which performs the first biting action on the workpiece, and the second peak does not exist.
Since the shape gradually emerges as the peak and the third peak are reached, the tip of the biting portion has little inherent cutting resistance at the tip of the twisted groove tap, and it is possible to bite the work material without dulling the sharpness. is there.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a front view of a right-handed right-handed groove tap having a chip discharge groove twisted in the same direction as the screw.
Is a thread portion of a tap, 2 is a shank, 3 is a biting portion, and 4 is a groove for discharging chips. FIG. 2 is a front view of a right-hand and left-hand twist groove tap having a chip discharge groove twisted in a direction opposite to the screw, in which 5 is a thread portion of the tap, 6 is a shank, 7 is a biting portion, 8 Is a groove for chip discharge.

FIG. 3 is a partial perspective view of the thread of the right-hand thread and right-hand thread groove tap, where arrow A indicates the biting portion side and arrow B
Indicates the shank side. The angle formed between the flank 10 and the rake face 9 on the shank side is obtuse and the angle between the rake face 9 and the rake face 9 is negative and the side rake angle is negative. The flank surface 11 is formed.

As shown in FIG. 3, in the cutting tap having a chip discharging groove twisted in the same direction as the screw, the flank face 11 having a negative rake angle in the thread of the thread portion and the side rake. A two-dot chain line showing an imaginary cylinder in which both flank surfaces of the flank surface 10 having a positive angle are secondly cut from the cutting edge and the width of the thread groove of the screw portion is equal to the width of the thread. As shown in FIG. 4, within the range of the flank face 10 on the side where the side rake angle is positive between 13 and the two-dot chain line 14 indicating the virtual cylinder in contact with the crest 12 of the thread portion of the tap, as shown in FIG. A negative lead 15 is applied to a regular screw lead, and a virtual cylinder 13 (see FIG. 3) in which the width of the thread groove of the screw portion is equal to the width of the thread and a virtual cylinder 13 in contact with the root of the screw. Horizontal gap between the two-dot chain line 16 indicating a simple cylinder Side flank 10 of the corner is positive
Is provided with a regular screw lead 17.

FIG. 5 shows a biting portion 3 of the tap according to the present embodiment.
FIG. 6 is a partial perspective view showing the details of FIG. In the drawing, reference numeral 18 denotes a cut surface of the biting portion 3, reference numeral 21 denotes a first peak of incomplete peaks, reference numeral 22 denotes a second peak, and reference numeral 23 denotes a third peak. As can be seen from the figure, the first thread 21 and the second thread 22 do not have a lead 15 which is negative with respect to the above-mentioned regular thread lead. There is a lead 15 that is negative with respect to the screw lead.

FIG. 7 is a partial perspective view of the thread of the right-hand thread and left-hand thread groove tap. In the figure, the same reference numerals as those described above denote the same components. Thread is rake face 24 on shank side
Is formed by a flank surface 25 where the angle between the flank surface 25 and the rake surface 24 on the biting portion side becomes an obtuse angle and the lateral rake angle becomes a negative angle. .

As shown in FIG. 7, in a cutting tap having a chip discharging groove twisted in the opposite direction to the screw, a flank surface 26 having a negative horizontal rake angle in a thread portion of the screw portion and a horizontal rake. The two-dot chain line 13 and the screw indicate a virtual cylinder in which both flank faces of the flank face 25 having a positive angle are subjected to second cutting from the cutting edge and the width of the thread groove is equal to the width of the thread. The flank face 25 having a positive lateral rake angle with the two-dot chain line 16 indicating a virtual cylinder in contact with the valley bottom is a regular screw lead 27 as shown in FIGS. Between the imaginary cylinder 13 in which the width of the thread groove is equal to the width of the thread and the two-dot chain line 14 (see FIG. 7) indicating the imaginary cylinder in contact with the crest 28 of the thread. Positive within the range of the flank surface 25 where the angle is positive Subjected to a lead 30 to be positive with respect to such screw lead.

FIG. 9 shows the biting portion 7 of the tap according to the present embodiment.
FIG. 10 is a partial perspective view showing the details of FIG. In the figure, reference numeral 31 denotes a cut surface of the biting portion 7, reference numeral 32 denotes a first peak of incomplete peaks, reference numeral 33 denotes a second peak, and reference numeral 34 denotes a third peak.
As can be seen from the figure, no lead 30 that is positive with respect to the above-mentioned regular screw lead is recognized in the first thread 32, and a regular thread lead is formed in the first thread 32 after the second thread 33. A positive lead 30 is present.

By forming the thread of the tap as described above, the flank face 15 for suppressing the over-advance phenomenon or the flank face 30 for preventing the lag phenomenon does not exist in the early stage of biting, so that the twist groove tap is formed. A good sharpness, which is an original characteristic of, can be obtained as it is, and the biting performance can be improved. Further, as the flank approaches the complete ridge, the effect of the flank surfaces 15 and 30 prevents an excessively advanced or delayed phenomenon, thereby enabling threading with an accurate lead. In the present invention, the thread may be formed entirely from the biting portions of the threaded portions 1 and 5, or may be formed only on a part of the complete thread.

[0020]

As described above, the spiral tap according to the present invention is capable of processing a female screw with an accurate lead without dulling the inherent sharpness and biting property of the twisted groove tap and without taking any special working method. An excellent effect of being able to perform is obtained.

[Brief description of the drawings]

FIG. 1 is a front view of a tap having a chip discharging groove twisted in the same direction as a screw.

FIG. 2 is a front view of a tap having a chip discharging groove twisted in a direction opposite to a screw;

FIG. 3 is a partially enlarged perspective view of a threaded portion of a right-handed right-handed groove tap;

FIG. 4 is a perspective view showing a state in which the present invention is applied to the screw portion of FIG. 3;

5 is a partially enlarged perspective view of a biting portion of the tap in FIG. 4;

FIG. 6 is a sectional view of FIG. 5;

FIG. 7 is a partially enlarged perspective view of a threaded portion of a right-handed left-handed groove tap;

FIG. 8 is a perspective view showing a state in which the present invention is applied to the screw portion of FIG. 7;

FIG. 9 is a partially enlarged perspective view of a biting portion of the tap in FIG. 8;

FIG. 10 is a sectional view of FIG. 9;

[Explanation of symbols]

REFERENCE SIGNS LIST 1 tap screw portion 2 shank 3 biting portion 4 chip discharging groove 5 tap screw portion 6 shank 7 biting portion 8 chip discharging groove 9 rake face 10 flank face where side rake angle is positive 11 Frank surface with a negative lateral rake angle 12 Thread crest 13 Two-dot chain line (cylinder) showing a virtual cylinder 14 Two-dot chain line (cylinder) showing a virtual cylinder in contact with the top of the thread 15 Regular screw Lead that is negative with respect to the lead 16 Two-dot chain line (cylindrical line) indicating a virtual cylinder in contact with the bottom of the valley 17 Reed of a regular screw 18 Cutting surface of the biting portion 21 First mountain 22 Second mountain 23 Third mountain 24 Rake Surface 25 Frank surface with a positive rake angle 26 Frank surface with a negative horizontal rake angle 27 Regular screw lead 28 Thread crest 30 Lead that is positive with respect to the regular screw lead 31 Cutting surface of bite portion 32 First mountain 33 Second mountain 34 Third mountain

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B23G 5/06

Claims (2)

(57) [Claims] 1. A cutting tap having a chip discharging groove twisted in the same direction as a screw, wherein a flank face having a negative lateral rake angle and a flank face having a positive lateral rake angle in a thread of a thread portion. A side rake angle between a virtual cylinder in which both flank surfaces are secondly cut from the cutting edge and the width of the thread groove is equal to the width of the thread and the virtual cylinder in contact with the root of the screw. The flank surface where is positive is the regular screw lead, and the virtual cylinder whose thread groove width is equal to the width of the thread and the virtual cylinder in contact with the top of the thread A spiral tap characterized in that a negative lead is applied to a normal screw lead within a range of a flank surface where a lateral rake angle between the positive rake angles is provided. 2. A cutting tap having a chip discharge groove twisted in a direction opposite to a screw, wherein a flank face having a negative lateral rake angle and a flank face having a positive lateral rake angle in a thread of a thread portion. A side rake angle between a virtual cylinder in which both flank surfaces are secondly cut from the cutting edge and the width of the thread groove is equal to the width of the thread and the virtual cylinder in contact with the root of the screw. The flank surface where is positive is the regular screw lead, and the virtual cylinder in which the width of the thread groove of the screw part is equal to the width of the screw thread and the virtual cylinder in contact with the top of the screw thread A spiral tap characterized in that a positive lead is applied to a regular screw lead within a range of a flank surface where a lateral rake angle between the positive rake angles is provided.