JP2601117Y2 - Drilling threaded connection tool for through holes - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a through hole threading connection tool for integrally drilling a through hole for machining a prepared hole in a workpiece and a thread cutting blade for machining an internal thread in the prepared hole. It is.

[0002]

2. Description of the Related Art There is a thread milling tool as a tool for cutting an internal thread. This is provided with a thread cutting blade having a shape corresponding to a thread groove of a female screw to be formed on an outer peripheral portion, and is attached to, for example, an NC milling machine or a machining center, and is driven to rotate around an axis. A female screw is cut on the inner peripheral surface of the prepared hole by being relatively moved in the circumferential direction and the axial direction of the prepared hole in a state where a notch is added to the prepared hole. Thread milling cutters are widely used. When cutting a female screw using such a thread milling cutter, it is necessary to pre-drill a prepared hole having substantially the same inner diameter as the inner diameter of the female screw to be formed as a pre-process, but in a method using a dedicated drilling tool, Due to the need for equipment and time for tool change, recently, a coupling tool in which a drilling tool is integrally provided at the tip of a thread milling cutter has been proposed. The tools described in JP-A-63-200916 and JP-A-3-184722 are examples, and the outer diameter of a thread cutting blade for machining a female screw is equal to the outside diameter of a drilling blade for machining a pilot hole. The diameter is the same as or slightly smaller than the outer diameter of the drilling blade in order to prevent interference with the inner peripheral surface of the prepared hole at the time of preparing the prepared hole.

[0003]

In the case of cutting a female screw having a lead with a screw blade having no lead, such as the above-mentioned screw milling cutter, interference cutting in which the thread groove shape of the female screw is larger than the shape of the screw cutting blade is required. Inevitably, this is when machining internal threads with large leads,
This becomes remarkable when the milling diameter is close to the root diameter of the internal thread to be machined. In the above-described conventional drilling threaded connection tool, since the outer diameter of the threading blade is substantially equal to the outer diameter (prepared hole diameter) of the drilling blade, the inner diameter of the female screw is generally about 85 to 95% of the root diameter,
Since the inner diameter is substantially equal to the pilot hole diameter, the outer diameter of the thread cutting blade with respect to the root diameter is also about 85 to 95%, and the interference cutting becomes a problem. As a countermeasure, the blade width of the thread cutting blade is reduced in consideration of the amount of cutting caused by interference, but such blade shape correction has a limit in strength.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a drilling and threading connection tool for a hole through which interference cutting is reduced.

[0005]

In order to achieve the above object, the present invention has a drilling blade for cutting a pilot hole at an axial front end, and a female screw in a pilot hole formed by the drilling blade. A multi-thread thread cutting blade without a lead to be cut is provided integrally on the axial rear side of the drilling blade,
A pilot hole penetrating the workpiece with a diameter substantially equal to the diameter of the drilling blade was formed by the drilling blade by being relatively moved in the axial direction with respect to the workpiece while being rotated around the axis. Later, an internal thread whose inner diameter is substantially equal to the pilot hole diameter is formed on the inner peripheral surface of the pilot hole by the multi-thread screw cutting blade by being relatively moved in the pilot hole in the axial direction and the circumferential direction while being rotationally driven around the axis. In a boring thread cutting coupling tool for a through hole to be cut, (a) the outer diameter of the multi-threaded screw cutting blade is 90% or less of the outer diameter of the drilled blade , and (b) the tool axial direction of the multi-threaded screw cutting blade. Before
At the end, the maximum diameter is larger than the outer diameter of the
Before cutting the internal thread with the multi-threaded cutting blade
The second chamfering blade for chamfering the opening of the prepared hole
It is characterized in that it is provided continuously on the top of the thread cutting blade .

[0006]

[Effects of the operation and the invention] In such a threaded connection tool for drilling a through-hole, since the outer diameter of the multi-threaded screw cutting blade is 90% or less of the outer diameter of the drilling blade, the outer diameter of the multi-threaded cutting blade is smaller than the root diameter of the internal thread to be machined. When the ratio of the outer diameter of the thread cutting edge is reduced, for example, when cutting an internal thread having an inner diameter of about 95% of the root diameter, the outer diameter of the multi-threaded cutting edge is 8 times the female thread root diameter.
When cutting a female screw having an inner diameter of about 85% of the root diameter, the outer diameter of the multi-threaded screw cutting blade is about 76% or less of the female screw root diameter. As a result, the amount of interference cutting is reduced, and the amount of correction of the blade shape in consideration of the interference cutting can be within a range in which there is no practical problem in terms of strength.

[0007] A specific description will be given of a case where a 60 ° triangular screw of M10 x 1.5 is machined. The allowable range t of the roundness of the valley in the JIS thread form is the dimension from the peak of the peak and the height of the peak. Up to 1/8, pitch 1.5m
In the case of a 60 ° screw of m, the height of the peak is about 1.299.
mm, t ≒ 0.162 mm. In this case, the outer diameter of the drilling blade is made equal to the inner diameter of the internal thread of 8.5 mm, and the outer diameter of the multi-threaded cutting blade is set to 100% thereof, that is, 8.
When a 5 mm, about the determined by calculation range t _a from the mountain peaks pointed rounded valley due to interference cutting 0.208m
m, which exceeds the allowable range t 範 囲 0.162 mm.
FIG. 7A shows a cutting state in this case.
The hatched area is the interference cutting range. On the other hand, when the outer diameter of the multi-threaded screw cutting blade is 90% of the outer diameter (inner diameter of the internal thread) of the drilling blade, that is, 7.65 mm, the range t _b from the peak of the rounded valley due to interference cutting to the peak is obtained. ≒ 0.114 mm, which is smaller than the allowable range t ≒ 0.162 mm. FIG. 7B shows the cutting state in this case, and the hatched portion is the interference cutting range. The outer diameter of the multi-threaded cutting blade is 80% of the outer diameter (inner thread inner diameter) of the drilling blade, that is, 6.8 m.
m, the range from the peak of the peak of the roundness of the valley due to interference cutting is 0.072 mm, and the outer diameter of the multi-threaded cutting blade is 70% of the outer diameter of the drilling blade (inner diameter of the internal thread), that is, 5. In the case of 95 mm, the range from the peak of the rounded valley due to interference cutting to the peak is 0.052 mm, and the outer diameter of the multi-threaded cutting blade is 6 times the outer diameter of the drilling blade (inner diameter of the internal thread).
In the case of 0%, that is, 5.1 mm, the range from the peak of the peak of the rounded valley due to interference cutting is 0.041 mm.
Becomes In the case of 90%, 0.162 is set between the allowable range t.
Although there is a margin of -0.114 = 0.048 mm, the peak of the thread cutting blade needs a flat portion or an R portion by cutting at least about 0.02 to 0.04 mm practically to prevent chipping. In consideration of the above, it is slightly less than 90%, and it is understood that it is practically necessary to make the content 90% or less.

[0008] Here, the smaller the ratio of the outer diameter of the multi-threaded screw cutting blade to the outer diameter of the drilling blade, the smaller the amount of interference cutting, but the flexural rigidity and torsional strength of the tool, bending force, chip discharge. Therefore, the outer diameter of the multi-threaded cutting blade is desirably set to a range of about 70% or more of the outer diameter of the drilling blade. If it is less than 70%, even if it is further reduced, the amount of interference cutting hardly changes, and it is necessary to emphasize the rigidity and strength of the tool.

[0009] Further, at the rear side in the tool axis direction with respect to the multi-threaded cutting blade, the maximum diameter is larger than the outer diameter of the drilling blade, and is relatively moved in the axial direction while being rotationally driven around the axis. If the first chamfering blade for chamfering is provided on the inlet side of the hole, the chamfering process can be continuously performed on the inlet side of the pilot hole with a single tool before or after machining of the internal thread by the multi-threaded screw cutting blade. This makes it possible to reduce processing equipment and processing time as compared with the case where a dedicated tool for chamfering is used.

In addition, at the front end in the tool axis direction of the multi-thread screw cutting blade, the maximum diameter is larger than the outer diameter of the multi-thread screw cutting blade, and when the female screw is cut by the multi-thread screw cutting blade, the opening of the pilot hole is formed. since the second chamfered edge performing chamfered section is <br/> continuously provided on top of the Tayama threaded blade,
When the female screw is machined by a multi-threaded cutting blade, chamfering on the exit side of the prepared hole is performed at the same time, so that machining equipment and machining time are reduced as compared with the case where a dedicated tool for chamfering is used. In addition, since the incomplete thread at the female screw opening is chamfered by the chamfering, the life of the internal thread due to the deformation or damage of such incomplete thread is prevented.

[0011] In addition, at least one of the front end and the rear end of the multi-thread screw cutting blade in the tool axis direction is provided with a multi-thread screw cutting blade having an outer diameter substantially equal to the outer diameter of the multi-thread screw cutting blade. If provided continuously at the top of the blade, the incomplete threads at the entrance side and exit side of the prepared hole will be removed when the internal thread is machined with a multi-threaded cutting blade, so deformation or damage of such incomplete threads , The life of the female screw is prevented from being shortened.

If the length of the multi-threaded cutting blade in the tool axis direction is substantially the same as the thickness of the workpiece on which the female screw is to be machined, the length of the tool hole required for machining the internal thread can be reduced. The number of revolutions is usually one and a half revolutions (bite, escape
(Except for the actual screw processing is one rotation) , so the second chamfer blade at the exit side of the pilot hole when cutting the internal thread
In addition, the incomplete thread on both the entrance side and the exit side of the prepared hole can be removed by the incomplete thread removal cutting edge. That is , when the female screw is cut by one revolution, the tool moves in the axial direction by one pitch, so that the length of the multi-thread screw cutting blade is shortened by about one pitch from the thickness of the workpiece. For example, it is possible to perform chamfering of about 1 pitch at maximum and removal of incomplete threads at both ends of the pilot hole. For the entrance side of the pilot hole,
The chamfering may be performed by the chamfering blade, and the second chamfering blade may be chamfered on the exit side of the prepared hole,
In this case, the length of the multi-threaded cutting blade in the tool axis direction may be larger than the thickness of the workpiece. If the length of the multi-threaded cutting edge in the tool axis direction is larger than the thickness of the workpiece, the second chamfering blade may be used to perform chamfering on the exit side of the prepared hole or may be performed using the incomplete mountain-removing cutting edge. To remove incomplete threads at both ends of the pilot hole, for example, shift the tool in the axial direction after female screw machining, or move the tool in the axial direction while revolving the tool many times in the circumferential direction of the pilot hole during female screw machining Thus, chamfering and incomplete thread removal may be performed on both ends of the prepared hole.

When the multi-threaded cutting blade and the drilling blade are formed on a common land extending in the tool axis direction, it is desirable to provide a margin around the land of the drilling blade. . That is, since the re-grinding of the multi-threaded cutting blade is usually performed on the rake face, when the drilling blade is formed on a common land with the multi-threaded screw cutting blade,
The rake face of the drilling blade is also ground at the time of re-grinding of the multi-threaded screw cutting blade, and if there is no margin, the outer diameter of the drilling blade and further the diameter of the pilot hole will decrease with grinding, but drilling If a margin is provided on the outer periphery of the land of the blade, the outer diameter of the drilling blade is kept constant regardless of the re-grinding of the multi-threaded cutting blade.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a perspective view showing an embodiment of the present invention. As shown in FIG.
FIG. 2 is a front view of the connecting tool 10 as viewed from a direction perpendicular to the axis, and FIG. 2 is a bottom view of the connecting tool 10 as viewed from the front end side. The coupling tool 10 integrally includes a shank 12 that is gripped by an NC milling machine or the like and driven to rotate about an axis, and a blade portion 14 that performs a cutting process on a workpiece. A pair of helical grooves 16 are formed in the blade portion 14 in a rotational cutting direction, that is, clockwise in this embodiment, symmetrically with respect to the axis, and a pair of lands that extend in the tool axis direction and are helically twisted. 18 are provided. In FIG. 2, the shank 12 is omitted.

A drilling blade 20 is provided at the front end of the land 18 in the tool axis direction. Cutting head 20 is provided with a bottom edge 22 and the peripheral cutting edge (leading edge) 24, d ₁ (the outer diameter of the cutting head 20) diameter of the peripheral cutting edge 24 is equal to or slightly smaller inner diameter of the internal thread to be processed In addition, a margin 26 having the same size is provided on the outer peripheral portion of the drilling blade 20 so as to be continuous with the outer peripheral blade 24. Also,
An intermediate portion of the land 18 in the tool axis direction, that is, a rear side of the drilling blade 20 in the tool axis direction with respect to the tool axis direction, is provided with a leadless multi-threaded cutting blade 28. Outer diameter d ₂ of the Tayama threaded blade 28, together are defined within the range of 70% to 90% of the diameter d ₁ of the outer peripheral cutting edge 24, the long in the tool axis direction of Tayama threaded blade 28 The dimension L is substantially the same as the thickness of the workpiece 30 (see FIG. 3) on which the female screw is to be machined. In this embodiment, the dimension L is set to a dimension shorter by about 0.5 pitch of the thread of the multi-threaded cutting blade 28. ing.

At the front end of the multi-threaded cutting blade 28 in the tool axis direction, that is, at a portion between the drilling blade 20 and the multi-threaded cutting blade 28, a chamfer having a smaller diameter from the drilling blade 20 toward the multi-threaded cutting blade 28. The blade 32 is the piercing blade 20
From the outer peripheral blade 24 to the top of the multi-threaded thread cutting blade 28. Further, at the rear end of the multi-threaded screw cutting blade 28 in the tool axis direction, an incomplete mountain-cutting cutting edge 34 having an outer diameter substantially equal to the outer diameter d ₂ of the multi-threaded screw cutting blade 28 is provided.
The multi-threaded cutting blade 28 is provided continuously at the top.
The lengths of the chamfering blade 32 and the incomplete ridge removing cutting edge 34 in the tool axis direction are substantially the same as one pitch of the threads of the multi-threaded screw cutting blade 28, respectively. The chamfer blade 32 corresponds to a second chamfer blade.

The torsion groove 16 reaches the front end of the shank 12, and a chamfering blade 36 having a diameter increasing toward the shank 12 is provided at the rear of the incomplete mountain removing cutting edge 34.
Are provided continuously to the incomplete mountain removing cutting edge 34. Chamfering blade 36 corresponds to a first chamfer edge, larger than the outer diameter d ₁ of the maximum diameter the cutting head 20 the same as the diameter of the shank 12.

The coupling tool 10 configured as described above is
For example, it is attached to an NC milling machine, a machining center, or the like, and is used for cutting a female screw. FIG. 3 shows a state in which the coupling tool 10 is positioned at a predetermined initial position with respect to the workpiece 30 fixed at the workpiece mounting position, and thereafter, as shown by arrows a to f. The female thread is machined in the workpiece 30 by being sequentially moved. FIG. 4 and FIG. 5 are views showing each process at the time of such internal thread processing, and (a) to (f) correspond to the reference numerals of the arrows in FIG. Hereinafter, the female screw processing step will be specifically described.

First, at the initial position shown in FIG.
0 is rotationally driven around the axis and is fed in the axial direction as shown by the arrow a. FIG. 4A shows this state. In the workpiece 30, a prepared hole 40 is cut by the drilling blade 20, and a chamfer is formed in an upper end opening of the prepared hole 40, that is, an opening on the entrance side. The chamfer 42 is performed by the blade 36. The coupling tool 10 is driven to rotate around the axis.
Is only sent in the axial direction while being
Diameter is substantially equal to the outer diameter d ₁ of the cutting head 20 is the same or slightly smaller inner diameter of the internal thread to be processed. afterwards,
The coupling tool 10 is lifted upward as shown by the arrow b, and is in the state of FIG. This position is such that the incomplete thread removing cutting edge 34 enters the prepared hole 40 by approximately one pitch of the thread of the multi-threaded screw cutting blade 28, and the lower end (tip) of the multi-threaded screw cutting blade 28 is threaded. 0.5
It is determined so as to protrude downward from the pilot hole 40 by about the pitch.

Next, the coupling tool 10 is moved in the radial direction of the prepared hole 40 as shown by an arrow c while being rotated around the axis, and the multi-threaded screw cutting blade 28 is
Cut into the inner peripheral surface of. The amount of movement in the radial direction is 寸 法 of the dimension obtained by subtracting the outer diameter d ₂ of the multi-threaded cutting blade 28 from the root diameter of the female screw to be formed. FIG. 4C shows this state, in which the multi-threaded cutting blade 2
8 are formed, and a part of the chamfer 42 is cut and removed by the incomplete thread removing cutting edge 34. Subsequently, the coupling tool 10 is rotated around the axis by one rotation and a half revolution around the center of the pilot hole 40 as shown by the arrow d while being rotated around the axis. .5 pitch upwards. The revolving direction of the coupling tool 10 is a counterclockwise direction when viewed from above, and as shown in FIG. 4D, the thread of the multi-threaded cutting blade 28 is formed on the inner peripheral surface of the prepared hole 40. A right-handed female screw 44 having a pitch equal to the pitch of the right-hand thread is formed. Further, the cutting edge 34 for removing incomplete ridges forms a cylindrical surface 46 having substantially the same inner diameter as the root diameter of the female screw 44 in a part of the chamfer 42, and the lower end opening of the female screw 44, that is, the opening on the outlet side. Is chamfered by the chamfering blade 32. Since the incompletely thread-removing cutting edge 34 and the chamfering blade 32 forming the cylindrical surface 46 and the chamfering 48 are all connected to the top of the multi-threaded screw cutting blade 28, they are formed by the multi-threaded screw cutting blade 28. The formation of incomplete threads at both ends of the female screw 44 is prevented.

Thereafter, the coupling tool 10 is moved to the center of the female screw 44 as shown by the arrow e, and the rotation about the axis is stopped. (E) of FIG.
Is in this state. Further, as shown by the arrow f, it is raised to the initial position, whereby a series of internal thread processing is completed. FIG. 5F shows this state.

Here, the coupling tool 10 of the present embodiment is described.
Since the outer diameter d ₂ of Tayama threaded blade 28 is less than 90% of the outer diameter d ₁ of the punching blade 20, the ratio of the outer diameter of Tayama threaded blade 28 against the root diameter of the internal thread 44 to be processed is small For example, when the inner diameter of the female screw 44 is about 95% of the root diameter, the outer diameter of the multi-threaded cutting blade 28 is 85% of the female screw root diameter.
% Or less, and when the inner diameter of the female screw 44 is about 85% of the root diameter, the outer diameter of the multi-threaded cutting blade 28 is about 76% or less of the female thread root diameter. As a result, the amount of interference cutting is reduced, and the amount of correction of the blade shape in consideration of the interference cutting can be within a range in which there is no practical problem in terms of strength.

The smaller the ratio of the outer diameter d ₂ of the multi-threaded screw cutting blade 28 to the outer diameter d ₁ of the perforating blade 20 is, the smaller the amount of interference cutting is, but the bending rigidity, torsional strength and bending resistance of the tool are accordingly reduced. The force and the chip discharge performance deteriorate. In contrast,
Binding tool 10 of this embodiment, since the outer diameter d ₂ of the Tayama threaded blade 28 is set at 70% or more ranges of the outer diameter d ₁ of the punching blade 20, the flexural rigidity and torsional strength, anti The bending force and the chip dischargeability are also maintained within practically acceptable ranges.

The hatched portion in FIG. 6 indicates that the ratio of the outer diameter d ₂ of the multi-threaded screw cutting blade 28 to the outer diameter d ₁ of the drilling blade 20 is 70 to 9.
In binding tool 10 of the present embodiment defined in the range of 0%, shows the range of the ratio of the outer diameter d ₂ of Tayama threaded blade 28 against the root diameter of the internal thread 44, the solid line internal thread 44
Is 95% of the root diameter, and the alternate long and short dash line indicates that the inner diameter of the female screw 44 is 85% of the root diameter. Also, FIG.
When the outer diameter d ₁ of the drilling blade 20 is the same as the inner diameter of the female screw 44,
is there.

On the other hand, the coupling tool 10 of this embodiment is provided with a chamfering blade 36 whose maximum diameter is larger than the outer diameter d ₁ of the drilling blade 20 at the rear side of the multi-thread screw cutting blade 28 in the tool axis direction. As shown in FIG. 4A, a chamfer 42 is formed in the opening at the upper end of the pilot hole 40 by cutting the pilot hole 40 by the drilling blade 20, so that a dedicated tool for chamfering is used. Processing equipment and processing time can be saved as compared with the case of using.

At the front end of the multi-threaded screw cutting blade 28 in the tool axis direction, a chamfering blade 32 having a larger diameter toward the boring blade 20 is connected to the multi-threaded screw cutting blade 28 and the boring blade 20 continuously. As shown in FIG. 4D, the internal thread 44 is provided by the multi-threaded cutting blade 28.
Chamfer 4 at the lower end opening of the female screw 44 when cutting
8, the machining equipment and machining time are reduced as compared with the case where a dedicated tool for chamfering is used. Further, since the incomplete thread at the lower end opening is chamfered by the chamfer 48, the life of the female screw 44 due to the deformation or damage of the incomplete thread is prevented from being shortened.

The outer diameter d of the multi-threaded screw cutting blade 28 is provided at the rear end of the multi-threaded screw cutting blade 28 in the tool axis direction.
An incomplete mountain-removing cutting edge 34 having an outer diameter equal to ₂ is provided continuously with the multi-threaded screw cutting blade 28, and FIG.
As shown in (d), when the female screw 44 is cut by the multi-threaded cutting blade 28, a cylindrical surface 46 is formed in a part of the chamfer 42, and an incomplete thread is formed in the upper end opening. Therefore, the life of the female screw 44 due to the deformation or damage of the incomplete thread is prevented from being shortened.

The length L of the multi-threaded cutting blade 28 in the tool axis direction is set to a dimension shorter than the thickness of the workpiece 30 by about 0.5 pitch.
As shown in (c), the cutting edge 34 for removing incomplete ridges enters the prepared hole 40 by approximately one pitch, and the tip of the multi-threaded screw cutting blade 28 becomes approximately 0.5 pitches. FIG. 4D shows a state in which the hole projects downward from the pilot hole 40.
As shown in FIG. 2, the female screw 44 is cut by being revolved 1.5 revolutions in the circumferential direction of the pilot hole 40 while being moved upward by 1.5 pitches. At the time of machining, the cylindrical surface 46 is cut by the incomplete mountain removing cutting blade 34, and the chamfer 48 is chamfered by the chamfering blade 32. Therefore,
The processing time is shortened as compared with the case where these cylindrical surfaces 46 and chamfers 48 are processed in a separate process.

Further, since the multi-threaded screw cutting blade 28 and the drilling blade 20 are provided on the common land 18, re-grinding of the multi-threaded screw cutting blade 28 is performed by grinding the rake face, that is, the twist groove 16. And the outer peripheral blade 2 of the boring blade 20
The rake face of No. 4 is also ground, and the outer peripheral blade 24 is retracted in a direction to narrow the land 18. However, since the outer peripheral blade 24 is provided with a margin 26,
Be peripheral cutting edge 24 in the direction to narrow the 8 retracts, the outer diameter d ₁ is kept constant. Thereby, the prepared hole 40 having a constant diameter is always cut regardless of the re-grinding of the multi-threaded screw cutting blade 28.

While one embodiment of the present invention has been described in detail with reference to the drawings, the present invention can be implemented in other forms.

For example, in the above-described embodiment, the case where the coupling tool 10 is revolved counterclockwise as viewed from above and moved upward in the axial direction to cut the right-handed female screw 44 has been described. The feed direction in the axial direction can be appropriately changed.

In the above embodiment, the pair of twist grooves 16
However, the number of the twist grooves can be changed as appropriate, and a straight groove parallel to the axis may be provided. The number of blades of the multi-threaded screw cutting blade 28 and the number of blades of the perforation blade 20 need not necessarily be the same.

Although the coupling tool 10 of the embodiment has the chamfering blades 32 and 36 and the cutting edge 34 for removing incomplete ridges, these may be appropriately provided as needed. The length L of the multi-threaded cutting blade 28 can also be set as appropriate.

Although not specifically exemplified, the present invention can be implemented in various modified and improved modes based on the knowledge of those skilled in the art.

[Brief description of the drawings]

FIG. 1 is a front view of a threaded connection tool for drilling a hole as one embodiment of the present invention.

FIG. 2 is a bottom view of the embodiment of FIG.

FIG. 3 is a view showing a state in which the workpiece is positioned at an initial position with respect to a workpiece when performing internal thread machining using the tool of FIG. 1;

FIG. 4 is a view showing the respective steps when performing internal thread machining using the tool of FIG. 1 together with FIG. 5;

5 is a diagram showing the respective steps when performing internal thread machining using the tool of FIG. 1 together with FIG. 4;

FIG. 6 is a view showing a ratio of an outer diameter of a multi-threaded screw cutting blade to a female screw root diameter in the tool of FIG. 1;

FIGS. 7A and 7B are diagrams for explaining the influence of the difference in the outer diameter of the multi-threaded cutting blade on the interference cutting, and FIG.
%, And (b) is a case of 90%.

[Explanation of symbols]

10: Through-hole drilling thread cutting tool 18: Land 20: Drilling blade 26: Margin 28: Multi-thread thread cutting blade 30: Workpiece 32: Chamfering blade (second chamfering blade) 34: Cutting edge for incomplete mountain removal 36 : chamfering blade (first chamfered edge) 40: pilot hole 44: female thread d _1: the outside diameter of the cutting head d _2: Tayama outer diameter of the threaded blade

Continuation of front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B23G 5/06

Claims (3)

(57) [Scope of request for utility model registration] 1. A multi-thread screw cutting blade having a lead hole for cutting a pilot hole at an axially front end portion and having no lead for cutting a female screw into a pilot hole formed by the drill hole. The drilling blade is integrally provided on the rear side in the axial direction, and is relatively rotated in the axial direction with respect to the workpiece while being rotated about the axis, so that the drilling blade has a diameter substantially equal to the diameter of the drilling blade. After machining a pilot hole that penetrates the workpiece, the multi-threaded screw cutting blade moves the pilot hole relative to the inner peripheral surface of the pilot hole by being relatively rotated in the axial direction and the circumferential direction while being rotated around the axis. In a boring thread cutting and coupling tool for a through hole, which cuts an internal thread having an inner diameter substantially equal to a prepared hole diameter, the outer diameter of the multi-threaded cutting blade is 90% of the outer diameter of the drilling blade.
In the following, at the front end of the multi-threaded cutting edge in the tool axis direction, a maximum
The diameter is larger than the outer diameter of the multi-thread
When cutting the internal thread with a cutting blade, the opening of the pilot hole
A second chamfering blade for chamfering the top of the multi-threaded cutting blade
Drilling threading coupling tool through hole, characterized in that provided in succession. 2. The multi-thread screw cutting blade is provided at at least one of a front end and a rear end of the multi-thread screw cutting blade with an outer diameter substantially equal to the outer diameter of the multi-thread screw cutting blade. 2. The tool according to claim 1 , wherein the tool is provided continuously with the top of the blade. Length in the tool axis direction wherein the Tayama threaded blade, drilling through hole according to claim 1 or 2 wall thickness of the workpiece to be machined internal threads to be substantially the same size Thread connection tool.