JPH06114631A - Multiple taper thread forming milling tool with boring cutter and method for using milling tool - Google Patents

Abstract

PURPOSE:To allow a single tool to cotinuously perform processing of a preparatory hole and processing of tapered female threads. CONSTITUTION:A cutting edge part 14 is equipped with multiple thread forming cutters 16, 18 free from lead in such a taper as reducing diameter toward the foremost part, at which a boring cutter 22 is furnished having an outside diameter equal substantially to or smaller than the outside diameter of the thread forming cutters 16, 18 at their minor diameter ends. In boring a preparatory hole with this type of taper thread milling tool 10, the feed S in axial direction per turn of a cutter tool is set in relation to the number X of edges of the thread forming cutters 16, 18 and the pitch P of the threads so as to substantially meet the formula No.1, where (n) is an integer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-tapered thread milling machine with a piercing blade, which is integrally provided with a piercing blade for machining a pilot hole in a workpiece and a thread cutting blade for machining a taper female screw in the pilot hole. It is about how to use it.

[0002]

2. Description of the Related Art As a tool for cutting a taper female screw, there is a multi-tapered tape milling machine. This is equipped with a thread cutting blade having a shape corresponding to the thread groove of the taper female screw to be formed in the outer peripheral portion in a state where a plurality of thread cutting blades are connected in the axial direction without a lead, and is attached to, for example, an NC milling machine or a machining center. While being driven to rotate about its axis, it is moved relatively to draw a helix line of the taper female screw with respect to the prepared hole while making a cut on the inner peripheral surface of the prepared hole previously formed in the workpiece. A taper female screw is cut on the inner peripheral surface of the prepared hole.

[0003]

However, when a female screw is machined by using such a multi-tapered tape milling machine, a prepared hole having substantially the same size as the inner diameter of the tapered female screw to be formed as a pre-process is machined. At that time, it was necessary to use a dedicated drilling tool for drilling a prepared hole. In addition, equipment and time were required for exchanging the tool for this pilot hole and the multi-thread taper screw milling machine.

The present invention has been made in view of the above circumstances, and an object of the present invention is to make it possible to successively perform a pilot hole machining and a taper female thread machining with a single tool. .

[0005]

In order to achieve the above object, the present invention provides a shank portion and a blade portion provided with a tapered multi-lead thread cutting blade having a taper shape which becomes smaller in diameter toward the tip side. In a multi-threaded taper screw milling machine that has a coaxial and cuts a taper female screw, at the tip of the blade portion, the outer diameter of the small-diameter end side of the multi-threaded screw cutting blade is substantially the same as or smaller than the outer diameter. It is characterized in that a piercing blade is provided.

Further, when a taper female screw is machined on a workpiece by using the multi-tapered thread milling cutter with a piercing blade, the multi-tapered screw milling machine with a piercing blade is driven to rotate about an axial center thereof. By relatively moving in the axial direction with respect to the workpiece, when the tapered pilot hole is cut by the drilling blade and the multiple thread cutting blade,
The axial feed amount S per one rotation of the multi-thread taper screw milling machine with a punching blade is expressed by the following equation (1) with respect to the number X of the multi-thread thread cutting blade and the pitch P of the thread. It is characterized in that it is set to be substantially satisfied.

[0007]

[Equation 2]

[0008]

In the multi-taper taper screw milling machine with a punching blade, the outer diameter of the small-diameter end side of the multi-thread screw cutting blade is provided at the tip of the blade portion having the tapered multi-thread screw cutting blade. Since a piercing blade with an outer diameter approximately the same as or smaller than that is provided, the piercing blade and the multi-threaded thread cutting can be performed by rotating the shaft and rotating the shaft relative to the workpiece. It becomes possible to cut the tapered pilot hole by the blade, and it is possible to continuously cut the pilot hole and the tapered female screw with a single tool. For this reason, equipment for tool replacement is not required, the processing time is shortened, the efficiency is significantly improved, and the processing cost is reduced.

Here, when the above-mentioned multi-tapered tape milling cutter with a piercing blade is used, the multi-tapered tape milling cutter with a piercing blade is driven to rotate about its axis while being axially rotated with respect to the workpiece before cutting the taper female screw. By relatively moving in the direction, when machining a tapered pilot hole with a piercing blade and a multi-threaded thread cutting blade, a taper part with a diameter larger than that of the piercing blade is mainly formed by the crest part of the thread Sequential cutting will be performed. At that time, the feed amount S in the axial direction per one rotation of the multi-tapered thread milling cutter with a drilling blade will be compared with the number X of the multi-threaded thread cutting blades and the pitch P of the thread If it is set so as to substantially satisfy the above formula (1), the cutting positions cut at the crests of the multi-threaded thread cutting blade will be offset from each other between the crests in which the cutting order is forward and backward in the axial direction. , So that cutting the uncut portion of the small diameter side crest preceding respectively.

Specifically, for example, in the case of one having two multi-threaded thread cutting blades in the circumferential direction, as shown in FIG.
The feed amount S _22, which is the distance from the first screw thread 36 of the multi-threaded thread cutting blade 16 to the position A where the first screw thread 36 was cut one revolution before, the number of blades X is 2, and the positive integer n is 2. In the above (1)
When set to satisfy the equation, the first thread 36
The second screw thread 38, which is rearward by the pitch P from the position B, is the position B where the first screw thread (not shown) of the second multi-threaded thread cutting blade on the opposite side to the axis is cut one and a half revolutions before and the above position. It is located at the midpoint of A. Therefore, the second screw thread 38 is
The first thread 36 and the first thread of the second multi-thread thread cutting blade will cut the uncut portion, the width of the chips will become narrower, the cutting depth will become larger, and the cutting resistance will be good. Various cutting processes are possible. In addition, the example of FIG.
In the case where the number of flutes X is 2 and the positive integer n is 3, the second screw thread that is separated from the first screw thread 36 of the first multi-threaded thread cutting blade 16 by the pitch P with respect to the feed amount S _{23 at} this time. 38
Is located at the midpoint between the position where the first screw thread of the second multi-thread screw cutting blade is cut one and a half revolutions before and the position where the first screw thread 36 is cut two revolutions before and the same as in the case of FIG. Good cutting with less cutting resistance is performed.

When the feed amount S is set so as to satisfy the above expression (1) according to the number of blades X and the pitch P, a good cutting state can be obtained during drilling. The surface roughness of the inner peripheral cutting surface of the tapered pilot hole is improved, and the subsequent cutting process of the tapered female screw can be stably performed.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a front view of a multi-tapered thread milling machine (hereinafter, simply referred to as taper thread milling machine) 10 with a punching blade, which is one embodiment of the present invention, as seen from a direction perpendicular to an axis. The taper screw milling machine 10 is integrally provided with a shank portion 12 that is gripped by an NC milling machine or the like and is driven to rotate about an axis, and a blade portion 14 that cuts a workpiece. The blade portion 14 has a taper shape in which the diameter becomes smaller from the shank portion 12 side toward the tip side, and a pair of twisted grooves 20 twisted clockwise in the rotational cutting direction, that is, in this embodiment, is formed with respect to the axis. By being formed symmetrically, a pair of the first multi-threaded thread cutting blade 16 and the second multi-threaded thread cutting blade 18 having no lead are provided symmetrically with respect to the axis. Further, at the tip of the blade portion 14,
A piercing blade 22 having an outer diameter dimension slightly smaller than the outer diameter dimension of the pair of multi-threaded thread cutting blades 16 and 18 on the small diameter end side is provided. FIG. 2 is a bottom view showing the drilling blade 22 exclusively when the tapered screw milling cutter 10 is viewed from the tip side,
The piercing blade 22 includes the first multi-thread thread cutting blade 16 and the second
A pair of cutting blades 2 each continuous with the multi-threaded screw cutting blade 18
It has 4, 26. In FIG. 1, the twist groove 20 reaches the front end portion of the shank portion 12, and a chamfering blade 28 having a larger diameter toward the shank portion 12 is provided at an intermediate portion between the shank portion 12 and the blade portion 14. It is provided.

The taper screw milling machine 10 configured as described above is attached to, for example, an NC milling machine or a machining center and used for cutting a taper female screw. In the first step, the tapered screw milling cutter 10 is axially moved toward the workpiece 30 from a predetermined initial position while being rotationally driven about the axis, whereby the punching blade 22 and the pair of multi-threaded thread cutting blades are provided. Cutting is performed by 16, 18 to form a tapered pilot hole 32 shown in the right half of FIG.

In the second step, the taper screw milling cutter 10 is driven to rotate about its axis while the multi-threaded thread cutting blades 16,
It is moved upward by about 1 pitch of the thread of 18 and is moved in the radial direction of the prepared hole 32. FIG. 3 shows the state at this time, whereby the first multi-thread thread cutting blade 1
6 and the second multi-threaded thread cutting blade 18 cuts into the inner peripheral surface of the prepared hole 32. The amount of movement in the radial direction is approximately 1/2 of the dimension obtained by subtracting the outer diameters of the multi-threaded thread cutting blades 16 and 18 from the root diameter of the female screw to be formed. Next, the taper screw milling cutter 10 is rotated about the axis of the prepared hole 32 while being revolved about the axis of the prepared hole 32 in the clockwise direction, and the threads of the multi-threaded thread cutting blades 16 and 18 per revolution. It is moved downward by one pitch. Further, the radius dimension in the revolution at this time is the multi-threaded thread cutting blades 16, 1
The taper shape of No. 8 in other words, that is, the taper shape of the taper female screw to be formed, is gradually reduced with the downward movement. As a result, a right-handed taper female thread 34 having a pitch equal to the pitch of the threads of the multi-threaded thread cutting blades 16 and 18 is formed on the inner peripheral surface of the prepared hole 32.

After that, the taper screw milling cutter 10 is moved to the center of the female screw 34, and the rotation around the axis is stopped. Then, it is raised to the initial position, and a series of female thread processing is completed.

Here, when the taper screw milling cutter 10 is fed in the axial direction in the first step, the feed amount S is
The number of blades X (= 2) of the multi-thread thread cutting blades 16 and 18 and the pitch P of the threads are set so as to satisfy the above expression (1).

A detailed description will be given with reference to FIG. 4, which is an enlarged view of a part of the cutting portion on the side of the first multi-thread screw cutting blade 16,
The feed amount S _{22 in} the case of FIG. 4 is equal to that of the first multi-thread thread cutting blade 1
When the number of blades X of the multi-threaded thread cutting blade composed of 6 and the second multi-threaded thread cutting blade 18 is 2 and the positive integer n is 2, it is set so as to satisfy the formula (1). 4, the distance from the first screw thread 36 of the first multi-threaded thread cutting blade 16 to the position A at which the first screw thread 36 is cut before one rotation. The position of the second screw thread 38, which is behind the first screw thread 36 by the pitch P, is the same as the above position A, and the second multiple screw thread is 180 ° opposite to the first screw thread 36 and the axial center. The first thread (not shown) of the thread cutting blade 18 is substantially coincident with the midpoint between the position B cut one and a half rotations before. The second screw thread 38, which always maintains such a cutting positional relationship, cuts a portion left uncut by the first screw thread 36 and the first screw thread of the second multi-thread thread cutting blade 18. Similarly, since the third screw thread 40 maintains the same cutting positional relationship as the above with respect to the cutting position by the second screw thread 38, the third screw thread 40 is The portion left uncut by the second thread (not shown) of the second multi-thread screw cutting blade 18 will be cut. The same applies to the fourth and subsequent threads. That is, the cutting positions cut at the crests of the multi-thread screw cutting blades 16 and 18 deviate from each other between the crests in which the cutting order is the front and back in the axial direction, so that the uncut portions of the preceding small-diameter side crests are cut respectively. As a result, the width of the chips becomes narrower and the depth of cut becomes larger, and good cutting with less cutting resistance is performed.

FIG. 5 shows the case where the feed amount S ₂₃ is set so as to satisfy the relationship when the positive integer n in the equation (1) is set to 3, and in this case, the second screw thread 38 The position substantially coincides with the midpoint between the position C where the first screw thread of the second multi-threaded thread cutting blade 18 is cut one and a half revolutions before and the position D where the first screw thread 36 is cut two revolutions before. There is. Even in this case, the second screw thread 3 is maintained in a constant cutting positional relationship.
8 is the first of the first thread 36 and the second multi-thread thread cutting blade 18
In addition to cutting the uncut portion of the thread, similarly, the threads after the third thread 40 cut the uncut portion of the preceding thread to be cut. Although not shown,
The feed amount satisfying the relationship when the positive integer n in the expression (1) is 4 or more or 1 can be set, respectively, and the same cutting state can be obtained.

As described above, in the multi-taper taper screw milling machine 10 with a piercing blade of this embodiment, the multi-thread thread cutting blade 1
Since the piercing blade 22 is provided at the tip of the blade portion 14 provided with 6, 18, it is not necessary to prepare a dedicated tool for preparing a hole as in the conventional case, and the prepared hole 32 and the taper can be tapered with a single tool. The internal thread 34 can be continuously cut. For this reason, equipment for tool replacement is not required, the processing time is shortened, the efficiency is significantly improved, and the processing cost is reduced.

In the first step, when the tapered pilot hole 32 with the multi-tapered thread milling machine 10 with a piercing blade is cut, the axial feed amount S of the taper thread milling machine 10 is set to a large number. Number of thread cutting blades X (=
2) and the pitch P of the screw thread are set so as to substantially satisfy the above expression (1), the cutting is performed by each thread of the first multi-thread thread cutting blade 16 and the second multi-thread thread cutting blade 18. Since the position is displaced from the cutting position of the screw thread whose cutting sequence is front and rear in the axial direction, the succeeding screw thread cuts the portion left uncut by cutting the preceding screw thread. As a result, a good cutting state in which the width of the chips is narrow, the cutting depth is large, and the cutting resistance is small is obtained, the surface roughness of the inner peripheral cutting surface of the tapered pilot hole 32 is improved, and the second cutting is performed thereafter. The two-step taper female screw is stably cut.

A concrete example of processing a 1/16 taper taper female thread, which is the most popular among the taper female threads, is shown below.

[0022]

[Table 1]

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

For example, in the above embodiment, the multi-threaded thread cutting blade 1
Although the drilling blade 22 having an outer diameter slightly smaller than the outer diameter of the small diameter end of 6 and 18 was provided, the outer diameter of the multi-threaded thread cutting blade 16, 18 is substantially the same as the outer diameter of the small diameter end. A perforating blade may be provided.

In the above embodiment, the multi-threaded thread cutting blade 1 is used.
Although the number of blades of 6, 18 and the number of blades of the piercing blade 22 were the same,
These do not necessarily have to be the same.

In the above embodiment, a pair of twist grooves 20 are provided.
Although the pair of multi-threaded thread cutting blades 16 and 18 are provided by forming the, the number of blades X of the multi-threaded thread cutting blade is other than 2, or a straight groove parallel to the axis is provided. Is also good.

Further, in the above embodiment, the case where the taper screw milling machine 10 is revolved clockwise when viewed from the upper side and moved downward in the axial direction to machine the taper female screw 34 of the right screw has been described. The feed direction in the direction and the axial direction can be changed as appropriate.

Further, the taper screw milling machine 1 of the above embodiment
0 had a chamfering blade 28, but the chamfering blade 28
May be provided as needed.

Although not illustrated one by one, 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 drawings]

FIG. 1 is a front view of a multi-tapered thread milling machine with a piercing blade according to an embodiment of the present invention.

FIG. 2 is a bottom view showing a punching blade of the embodiment of FIG.

FIG. 3 is a cross-sectional view illustrating a step of performing internal thread processing using the taper screw milling cutter of FIG.

FIG. 4 is a cross-sectional view showing in detail a cutting state when processing a tapered pilot hole by the tapered screw milling cutter of FIG. 1.

5 is a cross-sectional view showing in detail a cutting state when a tapered pilot hole is machined by the taper screw milling cutter of FIG. 1, and is a diagram illustrating a case where the feed amount S is different from the case of FIG. 4;

[Explanation of symbols]

10: Multi-thread taper screw mill with drilling blade 12: Shank part 14: Blade part 16: First multi-thread screw cutting blade 18: Second multi-thread screw cutting blade 22: Drilling blade 30: Work piece 32: Prepared hole 34: Taper Female thread S ₂₂ , S ₂₃ : Feed amount P: Thread pitch

Claims (2)

[Claims] 1. A multi-thread taper screw having a shank portion and a blade portion having a taper-shaped multi-thread thread cutting blade having a taper lead, the diameter of which decreases toward the tip side, coaxially, for cutting a taper female thread. In a milling cutter, a multi-taper taper with a perforating blade, characterized in that a perforating blade having an outer diameter dimension substantially equal to or smaller than the outer diameter dimension on the small diameter end side of the multi-thread screw cutting blade is provided at the tip of the blade portion. Screw milling machine. 2. A shank portion and a blade portion provided with a multi-threaded thread cutting blade having a taper shape and having a taper shape whose diameter becomes smaller toward the tip end side are coaxially provided, and the tip end of the blade portion is provided.
Cutting a taper female screw on a workpiece using a multi-tapered thread milling cutter with a perforation blade provided with a perforation blade having an outer diameter dimension that is substantially the same as or smaller than the outer diameter dimension on the small diameter end side of the multi-threaded thread cutting blade. When machining, the multi-tapered thread milling cutter with a piercing blade is rotationally driven around the axis and relatively moved in the axial direction with respect to the workpiece, thereby forming a tapered shape by the piercing blade and the multi-threaded cutting blade. At the time of cutting the prepared hole, the feed amount S in the axial direction per one rotation of the multi-thread taper screw milling cutter with the drilling blade is set with respect to the number of blades X of the multi-thread screw cutting blade and the pitch P of the thread. The following equation 1 was set so as to substantially satisfy the following equation 1 A method of using a multi-tapered thread milling machine with a drilling blade, which is characterized in that