JP2005230933A - Threaded hole machining tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a threaded hole machining tool capable of obtaining an aimed effective thread diameter at both of a deep part and a shallow part of threaded hole depth. <P>SOLUTION: This threaded hole machining tool has a cutting tool formed with a thread machining edge part 13 on the outer peripheral surface to form an internally threaded hole in a workpiece. The internally threaded hole can be formed in the workpiece by revolving the cutting tool 11 around an axis of a prepared hole formed in the workpiece, along the inner peripheral surface of the prepared hole while rotating the cutting tool 11 around its own axis O<SB>2</SB>. When a direction toward the tip side along the axis O<SB>2</SB>of the cutting tool 11 is made an x-axis direction, the effective diameter at the cutting edge start side end part 13a in a region formed with the thread machining edge part 13 of the cutting tool 11 is made D<SB>0</SB>and an effective diameter in a position separated by a distance x in the x-axis direction from the cutting edge start side end part 13a in the region formed with the thread machining edge part 13 of the cutting tool 11 is made D(x), the distance x and an effective diameter enlarged quantity defined by y=(D(x)-D<SB>0</SB>)/2 are in the relation of a cubic function of y=ax<SP>3</SP>+bx<SP>2</SP>+cx (a: a positive number, b<SP>2</SP>-4ac<0). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a screw hole machining tool used when machining a female screw hole in a workpiece.

When forming a female screw hole in a workpiece, for example, it is common to form a pilot hole having a diameter smaller than the effective screw diameter, and to machine this pilot hole by helical cutting. Specifically, the blade tool in which the threaded blade is formed is brought into contact with the inner wall of the prepared hole formed in the workpiece, and the blade tool is rotated while rotating around the axis of the prepared hole. A female screw hole is formed by feeding the reel in the axial direction. There is also a screw hole machining tool capable of realizing pilot hole machining and female thread machining with a single tool (for example, Patent Document 1 below). This is because the drill blade is formed at the tip of the cutting tool and the thread groove is formed on the outer peripheral surface of the cutting tool so that the processing of the pilot hole and the processing of the female screw hole are performed with one tool. . Specifically, as shown in FIG. 2 (a), a drill blade 32 is formed at the tip of the blade 31 of the screw hole machining tool 30, and the screw machining blade is formed on the outer peripheral surface of the blade 31. 33 is formed. As shown in FIG. 2B, such a processing tool 30 is advanced toward the workpiece W ″ while rotating, so that the workpiece W ′ is formed by the drill blade portion 32 formed at the tip of the cutting tool 31. A pilot hole W1 '' is formed in '. Next, after the blade tool 31 is returned by a predetermined amount in the axial direction of the blade tool 31, the axis O ₁ ″ of the pilot hole W ₁ ″ and the shaft center O ₂ ″ of the blade tool 31 as shown in FIG. In a state in which is shifted by r in the radial direction, the blade 31 is rotated about the axis O ₂ ″ while revolving around the axis O ₁ ″ of the pilot hole W1 ″. By returning the one-lead blade 31 in the direction of the axis O ₂ ″ during the periodical revolution, the pilot hole W1 ″ of the workpiece W ″ is formed in the female screw hole W2 ″. Finally, as shown in FIG. 2D, the machining tool 30 is returned from the female screw hole W2 ″.
Japanese Patent No. 2660349

  However, when the female screw hole is formed in the workpiece by the above method, the effective diameter of the screw is the depth of the screw hole, especially when the depth of the female screw hole is deep or the effective diameter of the female screw hole is small. There is a problem that it is difficult to obtain the intended effective screw diameter by changing the direction. More specifically, as shown in FIG. 6, only the effective screw diameter smaller than the intended effective diameter can be obtained at the deep part of the depth of the female screw hole W2 ″. In the vicinity of the opening of W2 ″, the effective screw diameter is larger than the target effective screw diameter in the shallow portion. That is, the processed shape of the female screw hole W2 ″ is a shape that decreases toward the depth of the screw hole. This phenomenon was more noticeable as the diameter of the cutting tool was smaller, the machining depth was deeper, and the cutting conditions were higher, which hindered high-efficiency machining. In addition, such a problem does not occur only when the pilot hole machining and the female screw machining are performed with one tool. After the pilot hole is machined with a tool such as a drill, the female screw hole is formed with a tool such as a tap. This also occurs when processing.

  The present invention has been made in view of the present situation as described above, and provides a screw hole machining tool capable of obtaining an effective screw diameter aimed at a deep portion and a shallow portion of a screw hole. The task is to do.

When forming a female threaded hole in a workpiece, particularly when forming a deep female threaded hole using a tool having a small effective screw diameter, the inventor In order to solve the problem that the desired effective screw diameter cannot be obtained, an attempt is made to measure the effective female screw diameter of the female screw hole when the effective female screw diameter is not obtained. It was. Specifically, using a metric flat thread with M10, a pitch of 1.2 mm, and a blade length of 25 mm as defined in JIS B0205, a female screw is formed by the method shown in FIG. 2 for a workpiece composed of (material: ADC12). Processing was performed. Then, the amount of effective female thread diameter reduction at the position of the depth X (mm) of the female screw hole was measured from the end surface of the female screw hole formed in the workpiece, with the depth direction of the female screw hole being the X-axis direction. Here, as shown in FIG. 6, the female screw effective diameter reduction amount is defined as the effective female screw diameter at the end face of the female screw hole W2 ″ being d ₀ (mm) and the effective female screw diameter at the depth X being d. When (x) (mm), it is a value defined as Y (female thread effective diameter reduction amount) = (d ₀ −d (x)) / 2. The measurement of the female screw effective diameters d ₀ and d (x) can be performed using a screw limit gauge. The measured values of Y (the female thread effective diameter reduction amount) and X (the depth of the female thread hole) obtained as described above seemed to be blackened in FIG.

Further, since the measurement is performed as shown in FIG. 7, the relational expression of X and Y is obtained by the least square method from the values of the effective screw diameter reduction amount (Y) and the depth of the female screw hole (X). As shown, it is apparent that X and Y have a relationship of a cubic function of the Y = aX ³ + bX ² + cX (a: positive number, b ² -4ac <0) type. In other words, the graph in which the effective diameter of the female screw hole W2 ″ in the cross section including the axis of the female screw hole W2 ″ is plotted against the depth may form a cubic curve.

Since the female screw effective diameter reduction amount (Y) and the depth (X) of the female screw hole W2 ″ have a cubic function relationship as described above, the present inventor has described the helical described with reference to FIG. When the internal thread of the pilot hole is machined by cutting, the cutting tool that comes into contact with the inner peripheral surface of the pilot hole is deflected by escaping due to the cutting resistance. The knowledge that it was not possible was obtained. This is because the amount of bending of the cantilever at a position away from the fixed end of the cantilever is in a relation of the predetermined distance and a cubic function. In the cross section including the axis O ₁ ″ of W2 ″, the depth dependency of the effective diameter of the female screw hole W2 ″ becomes a cubic curve because it can be inferred that the bending of the cutting tool is the cause. .

  Therefore, as a result of intensive studies by the present inventors, in the cutting tool of the screw hole machining tool, the effective diameter of the region where the threading blade portion of the cutting tool is formed is increased from the blade base side to the tip side of the cutting tool. If it is formed in advance so as to increase in a cubic function, the edge of the female screw hole and the hole of the female screw hole are deformed when the cutting tool bends when the pilot hole of the work is threaded with the screw hole machining tool. It has been found that it is possible to correct the deviation of the effective diameter of the female screw from the back side, and the present invention has been completed.

  In other words, in order to solve the above-described problems of the present invention, the threaded hole machining tool of the present invention has a threaded blade portion formed on the outer peripheral surface, and rotates on its own axis while rotating on the workpiece. A threaded hole machining tool having a cutting tool for forming a female threaded hole in a workpiece by revolving around an axis center of the prepared hole along an inner peripheral surface of the formed prepared hole, The effective diameter in the region where the threaded blade portion is formed increases in a cubic function from the blade base side of the blade tool toward the tip side of the blade tool.

Furthermore, if the above-mentioned feature point is seen more specifically from another side, the threaded hole machining tool of the present invention has a threaded blade portion formed on the outer peripheral surface and rotates around its own axis. On the other hand, it is a screw hole machining tool having a cutting tool for forming a female screw hole in a workpiece by revolving around the axis center of the pilot hole along the inner peripheral surface of the pilot hole formed in the workpiece. Te, the direction toward the distal end side along the axis of the cutting tool and the x-axis direction, the effective diameter of the end portion of the threaded blade portion blade root side of the area formed of the cutting tool and D _0, When an effective diameter at a position separated by a distance x in the x-axis direction from an end on the blade base side of the region where the threaded blade portion of the cutting tool is formed is D (x), y = (D ( x) −D ₀ ) / 2 and the effective diameter expansion amount and the distance x are y = ax ³ + bx ² + cx (a : Positive number, b ² -4ac <0) type cubic function.

  In the above cubic function, the values of a, b, and c can be appropriately set as appropriate depending on the effective diameter of the cutting tool, the blade length, and the material of the workpiece.

  As described above, the effective diameter of the threaded blade portion of the blade tool increases in a cubic function as it goes from the end of the threaded blade portion toward the tip of the blade tool. When the blade is bent along the inner peripheral surface of the work hole, the outer peripheral shape of the tool that contacts the inner surface of the work hole is This coincides with the shape of the inner peripheral surface, and the deviation of the effective diameter of the female screw hole due to the bending of the cutting tool can be corrected. Therefore, it is easy to obtain a targeted effective diameter both on the workpiece end surface side of the female screw hole and on the deep side of the female screw hole.

The specific shape of the threading blade portion is, as described above, when the normal threading tool is used, the effective diameter reduction (Y) of the prepared hole and the depth (X) of the female thread hole. Is a cubic function relationship of Y = aX ³ + bX ² + cX (a: positive number, b, c: constant) type, and therefore y = (D (x) −D ₀ ) / 2 described above. The effective diameter expansion amount (y) of the threaded blade part of the cutting tool defined by ( ² ) is a cubic function of the type y = ax ³ + bx ² + cx (a: positive number, b ² -4ac <0). it can. This corresponds to transferring the cubic curve indicated by the internal thread effective diameter reduction amount (Y) to the outer peripheral surface shape of the threaded blade portion of the cutting tool. As a result, when the workpiece pilot hole is threaded using the threading tool of the present invention, the outer peripheral surface shape of the cutting tool that comes into contact with the inner peripheral surface of the workpiece pilot hole is a female screw hole having an effective diameter. This makes it easier to match the shape of the inner peripheral surface. Therefore, it is easier to obtain a target effective diameter both on the workpiece end face side of the female screw hole and on the deep side of the female screw hole.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Fig.1 (a) shows the outline of the tool for threading of this embodiment. A screw hole machining tool 10 shown in FIG. 1 (a) is capable of realizing pilot hole machining on a workpiece and female screw machining on the inner peripheral surface of the pilot hole with the same tool. Specifically, it has a blade 11 having a cylindrical shape, a drill blade 12 formed at the tip, and a threaded blade 13 formed on the outer peripheral surface near the tip. According to the screw machining tool 10 having such a configuration, the drill blade 12 formed at the tip of the cutting tool 11 is advanced with respect to the work to perform the pilot hole machining of the work, and then the cutting tool 11 is moved down. The pilot hole can be threaded as it is withdrawn from the hole.

1 (b) is in threaded tool 10 shown in FIG. 1 (a), shows a cross-sectional view including the shaft center O ₂ in the region where the threaded blade 13 of the cutting tool 11 is formed is there. In FIG. 1B, the radial size of the threaded blade 13 of the blade 11 is slightly exaggerated for ease of explanation. As shown in FIG. 1 (b), the effective diameter of the cutting tool 11 in the region where the threading blade portion 13 is formed increases in a cubic function toward the tip side of the cutting tool 11. More specifically, as shown in FIG. 1 (b), the direction toward the distal end side of the cutting tool 11 along the axis O ₂ of the cutting tool 11 as the x-axis direction, threaded blade 13 of the cutting tool 11 is formed the effective diameter of the end portion 13a of the blade root side of the area being a D _0, the x-axis direction from an end portion of the blade root side area of threading edge portion 13 of the blade member 11 is formed distance x When the effective diameter at the distant position 13b is D (x), the effective diameter expansion amount (y) defined by y = (D (x) −D ₀ ) / 2 is y = ax ³ + bx ² + cx It is a cubic function with respect to a distance x of (a: positive number, b ² -4ac <0) type.

Hereinafter, a method for machining a screw hole for using the above-described screw machining tool 10 will be described with reference to FIG. Basically, a _tapping a manner similar to that shown in the prior art. First, as shown in FIG. 2 (a), while rotating the cutting tool 11 of the threading tool 10 about its axial center O _2, by advancing the workpiece W, the workpiece W of the cutting tool 11 Cutting with the drill blade 12. Thereby, the pilot hole W1 can be formed in the workpiece | work W, as shown in FIG.2 (b). Further, a chamfering blade portion 14 is formed on the blade base side of the blade 11 so that the chamfering of the mouth can be performed simultaneously with the preparation of the workpiece W. In addition, since the outer diameter of the drill blade part 11 currently formed in the front-end | tip of the blade tool 11 is set slightly larger than the outer diameter in the threading blade part 13 of the blade tool 11, when forming the pilot hole W1, The threading blade 13 does not interfere with the inner peripheral surface of the pilot hole W1. Next, the cutting tool 11 is returned by about 1 to 2 pitches along the direction of the axis O _{2 of} the cutting tool 11 so that the chamfering blade 14 does not interfere with the workpiece W during female thread processing.

Next, female threading is performed by helical cutting. Specifically, as shown in FIG. 2 (c), the inner periphery of the pilot hole W 1 formed in the workpiece W is used for the threading blade portion 13 of the blade 11 that rotates about its own axis O _2. While pressing against the surface, the blade 11 is revolved about the axis O ₁ of the pilot hole W1 along the inner peripheral surface of the pilot hole W1, and the blade 11 is rotated by one lead while the blade 11 revolves for one cycle. Send in the direction of the minute axis. In this way, by revolving the blade 11 about the axis O ₁ at least for one period, the length (blade length) of the region where the threaded blade portion 13 of the blade 11 is formed (blade length) is substantially the same. A female thread groove can be formed on the inner peripheral surface of the pilot hole W1. Thereby, the prepared hole W1 can be internally threaded into the internally threaded hole W2. At this time, since the drill blade portion 12 formed at the tip of the cutting tool 11 also cuts the workpiece W2, a relief portion W3 is formed at the bottom of the formed female screw hole W2.

  At this time, as described above, in the threaded hole machining tool 10 of the present embodiment, the effective diameter of the cutting tool 11 increases in a cubic function from the end of the threaded blade 13 toward the tip. Like to do. Therefore, as shown in FIG. 3, even when the cutting tool 11 is pressed against the inner peripheral surface of the pilot hole W1, even if the cutting tool 11 bends, the outer periphery on the side in contact with the inner peripheral surface of the pilot hole W1 of the threaded blade portion 13 It is possible to match the shape of the inner peripheral surface of the female screw hole with an effective diameter aiming at the shape of the surface. As a result, it is possible to eliminate the problem that the actual effective diameter deviates from the effective diameter aimed at the end face side and the hole back side of the work W of the female screw hole W2.

  In order to helically cut the pilot hole W1 with the cutting tool 11 of the threading tool 10, the three-axis simultaneous control and the helical interpolation that can move the cutting tool 11 simultaneously in the three axes of the X axis, the Y axis, and the Z axis. This can be realized by using a processing machine equipped with a numerical control device having a function.

Finally, the axis O ₂ of the cutting tool 11 moves the blade 11 so as to be substantially coincident with the axis O ₁ of the internal thread hole W2, after releasing the threaded blade portion 13 from the inner peripheral surface of the internal thread hole W2 Then, the blade 11 is pulled up in the direction of its own axis O ₂ to complete the internal thread machining.

  Next, an embodiment of the present invention that is different from the above-described screw hole machining tool 10 will be described with reference to FIG. The screw hole machining tool 20 shown in FIG. 4 is different from the screw hole machining tool 10 shown in FIG. 1 in that the drill blade part 12 is not provided. In other words, pilot holes already formed in the workpiece are formed in the female screw holes, and when a female screw hole is formed in the workpiece, a tool such as a drill for forming the pilot hole in the workpiece is separately required. It is. As shown in FIG. 4 (a), the screw hole machining tool 20 has a cutting tool 21 that is formed in a cylindrical shape and has a thread machining blade portion 23 formed on the outer peripheral surface near the tip. More specifically, it is configured as a tap.

FIG. 4B shows a cross-sectional view including the axis O ₂ ′ in the region where the threading blade portion 23 of the cutting tool 21 is formed in the screw machining tool 20 shown in FIG. 4A. It is. In FIG. 4B, the radial size of the threaded blade portion 23 of the blade 21 is slightly exaggerated for ease of explanation. As shown in FIG. 4B, the effective diameter of the cutting tool 21 in the region where the threading blade portion 23 is formed increases in a cubic function toward the tip side of the cutting tool 21. More specifically, as shown in FIG. 4B, the direction toward the tip side of the blade 21 along the axis O ₂ ′ of the blade 21 is the x-axis direction, and the threading blade portion 23 of the blade 21 is the effective diameter and D ₀ in blade root side end portion 23a of the area formed, the distance from the blade root side end portion 23a of the region threading edge portion 23 of the blade member 21 is formed in the x-axis direction When the effective diameter at the position 23b separated by x is D (x), the effective diameter expansion amount (y) defined by y = (D (x) −D ₀ ) / 2 is y = ax ³ + bx It is a cubic function with respect to the distance x of the ² + cx (a: positive number, b ² -4ac <0) type.

Next, a screw hole machining method for using the screw hole machining tool 20 shown in FIG. 4 will be described with reference to FIG. First, a workpiece W ′ having a prepared hole W1 ′ is prepared. In order to form the pilot hole W1 ′ in the work W ′, a normal drill blade can be used. Next, as shown in FIG. 5, the tap 20 which is the tool 20 for threading holes is inserted into the prepared hole W1 ′, and the threading blade portion 23 formed on the cutting tool 21 of the tap 20 is inserted into the prepared hole W1 ′. It is made to contact | abut to the internal peripheral surface. Then, while rotating the blade 21 around its own axis O ₂ ′ and revolving around the axis O ₁ ′ of the pilot hole W1 ′, the blade 21 is rotated by one lead while the blade 21 revolves one cycle. Move in the direction of the branch axis O ₂ ′. As a result, the pilot hole W1 ′ can be internally threaded into the internal thread hole W2 ′.

  At this time, in the threaded hole machining tool 20 of the present embodiment, the effective diameter of the cutting tool 21 is increased in a cubic function from the end on the blade base side of the threaded blade 23 toward the tip. Yes. Therefore, similarly to the screw hole machining tool 10 shown in FIG. 3, even if the blade 21 is bent when the blade 21 is pressed against the inner circumferential surface of the pilot hole W1 ′, the outer peripheral surface shape of the thread machining blade portion 23 is aimed. It is possible to match the inner peripheral surface shape of the female screw hole having an effective diameter. As a result, the problem that the actual effective diameter deviates from the effective diameter aimed at the end face side and the hole back side of the workpiece W 'of the female screw hole W2' can be solved.

  Note that the cutting tool 21 of the threading tool 20 can be driven by a processing machine provided with a numerical control device having three-axis simultaneous control and a helical interpolation function.

Further, in the screw machining tool 20, the prepared hole W1 ′ formed in the workpiece W ′ may be either a through hole or a blind hole. Further, when the blade 21 moves in the direction of its own axis O ₂ ′ while revolving around the axis O ₁ ′ of the pilot hole W1 ′, the blade 21 is moved from the end face side of the pilot hole W1 ′ toward the back of the hole. May be moved, or the cutting tool 21 may be moved from the hole back side to the end face side of the pilot hole W1 ′. Specifically, as shown in FIG. 5 (b), when the pilot hole W1 ′ is a blind hole, the blade 21 is inserted into the pilot hole W1 ′ and from the hole back side of the pilot hole W1 ′. The form which moves the blade 21 toward an end surface side can be illustrated.

As described above, in the threaded hole machining tool of the present invention, the effective diameter in the region where the threaded blade portion of the blade is formed is a cubic function from the blade base side of the blade tool toward the tip side of the blade tool. Therefore, even if the cutting tool is bent when female thread processing is performed by helical cutting, it is easy to realize an effective diameter aimed at the end face side and the deep hole side of the female thread hole. Furthermore, in the screw hole machining tool of the present invention, the direction toward the tip side along the axis of the cutting tool is the x-axis direction, and at the end of the blade base side in the region where the threading blade part of the cutting tool is formed. When the effective diameter is D ₀ and the effective diameter at a position separated by a distance x in the x-axis direction from the edge of the blade base side of the region where the threaded blade portion of the blade is formed is Y (x), y The effective diameter expansion amount defined by = (D (x) −D ₀ ) / 2 and the distance x are the ^third -order of y = ax ³ + bx ² + cx (a: positive number, b ² -4ac <0) type Because of the function relationship, even when the cutting tool is bent by helical cutting, the effective diameter aimed at the end face side of the female screw hole and the deep side of the hole can be more easily realized.

  In the screw machining tool of the present invention, the effective diameter and the blade length of the tool are not particularly limited, but the present invention is particularly remarkable when the effective diameter of the tool is small and the machining depth is deep. Therefore, it is more effective to apply to a tool having a small effective diameter of the threading blade portion of the cutting tool and a long blade length of the threading blade portion. Specifically, it can be particularly preferably employed for a screw hole machining tool corresponding to a metric flat thread of M10 or less, more preferably M6 or less as defined in JIS B0205.

The figure explaining one Embodiment of the tool for screw hole processing of this invention. The figure explaining the process of forming a female screw hole in a workpiece | work with the tool for screw hole processing. The figure explaining the effect | action of the tool for screw hole processing shown in FIG. The figure explaining one Embodiment different from FIG. 1 of the tool for threaded hole processing of this invention. The figure explaining the process of forming a female screw hole in a workpiece | work with the tool for screw hole processing shown in FIG. The figure which shows the internal peripheral surface shape of a female screw hole when processing with the tool for conventional screw hole processing. The figure which shows the relationship between the female screw effective diameter reduction amount and the depth of a screw hole in the female screw hole shown in FIG.

Explanation of symbols

10, 20, 30 Thread processing tool 11, 21, 31 Cutting tool 13, 23, 33 Thread processing blade portion 13a, 23a End portion on the blade base side of the thread processing blade portion W, W ′, W ″ Work W1, W1 ', W1''pilot hole W2, W2', W2 '' internal thread hole O _{1, O 1} ', _{O 1'} axis O 'of the prepared hole _{2, O 2', O 2} 'axis' of the cutting tool

Claims (2)

A threaded blade is formed on the outer peripheral surface, and revolves about the axis of the pilot hole along the inner peripheral surface of the pilot hole formed in the workpiece while rotating about its own axis. A screw hole machining tool having a cutting tool for forming a female screw hole in a workpiece,
A screw hole, wherein an effective diameter of the cutting tool in a region where the threaded blade portion is formed increases in a cubic function from a cutting edge side of the cutting tool toward a tip side of the cutting tool. Tool for processing. A threaded blade is formed on the outer peripheral surface, and revolves about the axis of the pilot hole along the inner peripheral surface of the pilot hole formed in the workpiece while rotating about its own axis. A screw hole machining tool having a cutting tool for forming a female screw hole in a workpiece,
The direction toward the tip side along the axis of the cutting tool is the x-axis direction, and the effective diameter at the end of the cutting tool in the region where the threading blade is formed is D ₀ , Where D (x) is the effective diameter at a distance x in the x-axis direction from the end on the blade base side of the region where the threaded blade portion is formed, y = (D (x) The effective diameter expansion amount defined by −D ₀ ) / 2 and the distance x are in the relationship of a cubic function of the type y = ax ³ + bx ² + cx (a: positive number, b ² -4ac <0). A screw hole machining tool characterized by that.

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