Tap tool and tap processing method

Abstract

The tap tool (10) has a rotation axis (C r ), in a state where the central axis (C6) of a pre-drilled hole (6') provided in a workpiece is aligned with the rotation axis, the pre-drilled hole is processed into a threaded hole (6), characterized in that the tap tool (10) comprises: a threaded portion (14), having a blade portion (14a) for processing a thread groove of the threaded hole; a pad portion (15, 16) located behind the blade portion in the rotation direction, the pad portion being engaged with the thread groove processed by the blade portion during the processing of the thread groove; and a non-engaging portion (17), forming a space (20) between the threaded hole and the non-engaging portion when viewed in a cross-section with the rotation axis aligned with the central axis of the threaded hole. The space has a size such that when the tap tool is displaced in the threaded hole in a direction orthogonal to the rotation axis from the state where the rotation axis is aligned with the central axis of the threaded hole, the engagement between the threaded portion and the thread groove and the engagement between the pad portion and the thread groove can be released simultaneously.

Description

Technical Field

[0001] The invention relates to a tap tool for processing a pre-drilled hole arranged on a workpiece into a threaded hole and a tap processing method. Background Art

[0002] When tap machining is performed using a machining center and a tap tool mounted thereon, the process is performed by synchronizing rotation with linear feed, which is called synchronous tap machining. In synchronous tap machining, when the tap tool is pulled out from the processed threaded hole, the rotation and feed also need to be synchronized. For this reason, the time required to pull out the tap tool needs to be roughly equal to the time it takes to advance the tap tool to machine the thread groove. However, the creator of the machining program needs to select the type of tool material suitable for the type of material being cut, or optimize the rotation speed of the spindle of the machining center based on the torque characteristics of the spindle motor of the machining center or the diameter and depth of the threaded hole, etc., in order to shorten the tap machining time in tiny units of less than 1 second.

[0003] Patent document 1 discloses a tap tool (thread cutting milling cutter) used together with an NC milling cutter or a machining center. In order to comprehensively shorten the processing time, the tap tool of Patent document 1 is formed to not only perform tap processing but also perform pre-drilling processing simultaneously with tap processing. To this end, the tap tool of Patent document 1 has a bottom blade for pre-drilling processing and a blade as a cutting edge for tap processing on the outer periphery of the tool. In addition, the tap tool has an outer diameter that is significantly smaller than the inner diameter of the threaded hole to be processed, and the tap processing performed by it is performed by rotating the tap tool (rotating) around the main shaft of the machine tool and revolving around the central axis of the threaded hole.

[0004] Prior Art Literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 3-184721 Summary of the invention

[0007] Problems to be solved by the invention

[0008] According to the tap tool of Patent Document 1, since the outer diameter of the tap tool is smaller than the inner diameter of the threaded hole, bending stress due to cutting resistance is generated in the tap tool during tap processing. As a result, there is a concern that the dimensional accuracy of the threaded hole will be reduced due to the deflection of the tap tool, especially when the tap tool is slender. In addition, since the tap processing in Patent Document 1 is performed by a single blade, it is expected that the tap processing time will increase compared to conventional ordinary tap tools. As a result, it is considered that there is a limit to the effect of conventional tap processing methods when the processing time including pre-drilling is compared.

[0009] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a tap tool that can perform tap processing in a short time while maintaining the same accuracy as conventional ones.

[0010] Solutions to Solve Problems

[0011] In order to achieve the above-mentioned purpose, according to the present invention, there is provided a tap tool, which has a rotation axis, and processes the pre-drilled hole provided in a workpiece into a threaded hole in a state where the central axis of the pre-drilled hole is aligned with the above-mentioned rotation axis, and is characterized in that the above-mentioned tap tool comprises: a threaded portion, the threaded portion having a blade portion for processing a thread groove of the above-mentioned threaded hole; a pad portion, the pad portion being located behind the above-mentioned blade portion in the rotation direction and engaging with the above-mentioned thread groove processed by the above-mentioned blade portion during the processing of the above-mentioned thread groove; and a non-engaging portion, the non-engaging portion forming a space between the above-mentioned threaded hole when viewed in a cross-section with the above-mentioned rotation axis aligned with the central axis of the above-mentioned threaded hole, the above-mentioned space having the following size: when the tap tool is displaced in the above-mentioned threaded hole in a direction orthogonal to the above-mentioned rotation axis from the state where the above-mentioned rotation axis is aligned with the above-mentioned central axis of the above-mentioned threaded hole, the engagement between the above-mentioned threaded portion and the above-mentioned thread groove and the engagement between the above-mentioned pad portion and the above-mentioned thread groove can be released at the same time.

[0012] Furthermore, according to the present invention, there is provided a tap processing method, characterized in that it includes: a step of aligning the rotation axis of a spindle of a machine tool on which a tap tool is mounted with the central axis of a pre-drilled hole provided in a workpiece; a tap processing step of performing tap processing on the pre-drilled hole by rotating the tap tool and moving forward in the direction of the rotation axis; a tap tool displacement step of displacing the tap tool in a direction orthogonal to the rotation axis of the spindle so that the engagement between the threaded portion including the cutting edge of the tap tool and the thread groove of the threaded hole formed in the workpiece is released; and a retreating step of retreating the tap tool in the direction of the rotation axis without rotating the tap tool.

[0013] Effects of the Invention

[0014] According to the present invention, after machining, the tap tool that has been disengaged from the thread groove of the threaded hole by moving in a direction perpendicular to the rotation axis can be extracted from the threaded hole at high speed in the direction of the rotation axis without rotating the tap tool. Due to the effect of this high-speed extraction, the machining time including the time to return to the machining start point can be shortened.

[0015] Furthermore, according to the present invention, since the cutting resistance is supported by the threaded hole via the pad portion, the deflection of the tap tool due to the cutting resistance is extremely small, and as a result, the machining accuracy is the same as that when the conventional tap tool 210 is used. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 1 is a front view of a machine tool and a tap tool according to an embodiment of the present invention mounted on its spindle head.

[0017] Figure 2 is a perspective view of a tap tool according to an embodiment of the present invention.

[0018] Figure 3 4 is a front view of a tap tool according to an embodiment of the present invention.

[0019] Figure 4 It is a cross-sectional view of a tap tool and the threaded hole produced by it.

[0020] Figure 5 It shows the relationship between cutting resistance and its main cutting force and back force. Figure 4 Same cross section.

[0021] Figure 6 The tap tool is shown Figure 4 Cross-sectional view of the tap tool and threaded hole in a displaced state.

[0022] Figure 7 It is a stereogram of a typical existing tap tool. DETAILED DESCRIPTION

[0023] Figure 1 1 is a diagram showing a machine tool 100 which is a general vertical machining center and a tap tool 10 according to an embodiment of the present invention mounted thereon. Figure 1 The machine tool 100 comprises: a bed 102 as a base fixed on the floor of the factory; a Y-axis slider 104 arranged to be movable in the Y-axis direction on the upper surface of the bed 102, and a workpiece 8 is clamped and fixed on the Y-axis slider 104; Figure 1 The support 108 is arranged vertically on the upper surface of the right side; the front surface of the support 108 can be in the X-axis direction ( Figure 1 The X-axis slider 110 is movable in the direction perpendicular to the paper surface; the Z-axis slider 112 is arranged to be movable in the Z-axis direction relative to the X-axis slider 110; and the spindle 114 is fixed to the Z-axis slider 112 and supports the spindle 114 so that it can rotate in a vertical direction. r The machine tool 100 is configured in this way, so that the spindle head 116 can be relatively moved and positioned with respect to the workpiece 8. In addition, the machine tool 100 is further provided with a control device 120 and an automatic tool changer (not shown).

[0024] The machine tool 100 performs tapping as so-called synchronous tapping, that is, a process in which the rotation of the spindle 114 is synchronized with the feed in the Z-axis direction. In this specification, the linear movement of the tap tool 10 in the Z-axis direction during tapping is also referred to as forward movement, and the linear movement of the tap tool 10 in the Z-axis direction to remove the tap tool 10 from the threaded hole 6 is also referred to as backward movement. r and the tap tool's rotation axis C r The same reference numerals are used throughout the specification to indicate the same reference numerals.

[0025] A perspective view of a tap tool 10 according to an embodiment of the present invention is shown in Figure 2 , the main view is shown in Figure 3 , just after processing Figure 3 The cross-sectional view along the cutting line A-A of FIG. 1 is shown together with the threaded hole 6. Figure 4 The tap tool 10 is located at its rotation axis C r In a state where the central axis C6 of the pre-drilled hole 6' provided in the workpiece is aligned, tapping is performed, that is, processing to form the pre-drilled hole 6' into a threaded hole 6. Figure 4 In the figure, the circle indicated by reference numeral 6 a corresponds to the inner diameters of the pre-drilled hole 6 ′ and the threaded hole 6 , and the circle indicated by reference numeral 6 b corresponds to the diameter of the valley bottom of the threaded hole 6 , ie, the nominal diameter of the tap tool 10 .

[0026] The tap tool 10 has a shank portion 11 at the base end and a processing portion 12 at the tip end. A tapered portion 13 is provided at the tip of the processing portion 12. The processing portion 12 has: r The male threaded portion 14 is formed asymmetrically and has a plurality of blades 14a for processing the thread groove of the threaded hole 6; male threaded pads 15 and 16 that engage with the thread groove processed by the blade 14a; and a non-engaging portion 17 that does not contact the pre-drilled hole 6' and the threaded hole 6 during processing. The threaded portion 14 has a plurality of thread teeth arranged at intervals with a predetermined thread pitch in the longitudinal direction, and the blade 14a is arranged on the front side of the rotation direction of each of the plurality of thread teeth. In addition, in the present embodiment, the tap tool 10 forms a triangular thread thread groove.

[0027] exist Figure 7 For comparison purposes, a typical conventional tap tool 210 is shown in FIG. The tap tool 210 has a threaded portion 214 having a cutting edge 214a which is divided into four parts by four grooves 218 extending in the longitudinal direction for the flow of cutting oil. Figure 7 In the case of the conventional tap tool 210, when viewed in cross section, the four threaded portions 214 are arranged at 90 degree intervals.

[0028] In contrast, in the tap tool 10 according to the embodiment of the present invention, one threaded portion 14 is disposed only at Figure 4 Roughly between 8 and 9 o'clock. Figure 4 The threaded portion 14 of the tap tool 10 can be connected to the conventional tap tool 10 by its blade 14a. Figure 7 The thread groove is processed in the same manner as the threaded portion 214 of the embodiment. In addition, the principle of cutting by the blade 14a is the same as before, and therefore, the blade 14a has a rake surface 14b in the same manner as before. Figure 4 The same cross-section Figure 5 During the tapping process in the rotation direction T, the cutting resistance R acting on the tip of the cutting edge 14a of the tap tool 10 as a reaction force to the cutting force is c and its back force R b And the main cutting force R p It is shown as a vector.

[0029] exist Figure 4 In the embodiment, the tap tool 10 is formed to rotate clockwise. The pads 15 and 16 are provided behind the threaded portion 14 in the rotation direction. In the present embodiment, two pads are provided, namely, the first pad 15 and the second pad 16. A first groove 18 is provided between the first pad 15 and the threaded portion 14, and a second groove 19 is provided between the first pad 15 and the second pad 16. Since the first groove 18 and the second groove 19 are respectively formed in front of the first pad 15 and the second pad 16 in the rotation direction, the cutting fluid is efficiently supplied to the pads 15 and 16 via the grooves 18 and 19. As a result, the lubrication between the pads 15 and 16 and the workpiece 8 is improved, and the tap tool 10 and the workpiece 8 are protected from damage caused by friction between the surface of the thread groove formed by the blade 14a and the pads 15 and 16.

[0030] Each of the pads 15 and 16 has a male thread similar to the threaded portion 14, but does not have a blade 14a. It can be said that the radius of the male thread of the pads 15 and 16 is slightly smaller than the radius of the male thread of the threaded portion 14, and is formed to be threadedly engaged with the thread groove of the threaded hole 6 formed by the blade 14a of the threaded portion 14.

[0031] The support portions 15 and 16 are provided to support the threaded hole 6 against the cutting resistance R generated during machining. c In this embodiment, the second pad portion 16 mainly plays this role. Therefore, the cutting resistance R extending from the blade portion 14a is c The direction is toward the second pad portion 16. Cutting resistance R c The cutting resistance R is transmitted to the thread groove of the threaded hole 6 via the second pad portion 16 and supported by it. c The direction of can be changed by changing the angle of the rake surface 14b.

[0032] The non-engaging portion 17 is a curved smooth surface. Figure 4 The space 20 is formed between the non-engaging portion 17 and the inner diameter of the threaded hole 6. The size of the space 20 is as follows: Figure 4 The tap tool 10 is in a state of being aligned with the rotation axis C r When the direction and distance indicated by the arrow S are orthogonal to each other, that is, Figure 6 When the position shown is displaced, the engagement between the threaded portion 14 and the thread groove of the threaded hole 6 and the engagement between the first and second pad portions 15 and 16 and the thread groove can be released at the same time. In addition, the size of the space 20 is formed slightly larger with a margin. In addition, during cutting, the space 20 plays the role of a path for supplying cutting fluid to the blade tip portion 14a and a path for discharging chips generated by cutting, which has the effect of improving the quality of the machined surface and extending the tool life.

[0033] like Figure 6 As shown, the tap tool 10 whose engagement with the threaded portion 14 or the pad portions 15, 16 and the threaded groove is released can be removed from the threaded hole 6 by retreating in the direction of the rotation axis. The removal of the tap tool 10 does not involve rotational motion as in the past, so it can be performed at high speed.

[0034] However, in the machine tool 100 of this embodiment, the reference line (hereinafter referred to as the “origin line”) L at which the rotation angle of the spindle 114 is 0 degrees is o exist Figure 4 as well as Figure 6 Extends at 3 o'clock. Figure 4 as well as Figure 6 In the figure, the tap tool 10 is relative to the original line L o The rotation angle (hereinafter also referred to as "phase angle") of the blade 14a is exemplified as 180 degrees. Since the rotation speed of the tap tool 10 required for machining is different if the depth of the threaded hole 6 is different, the phase angle of the tap tool 10 at rest after machining is different for each threaded hole 6. Therefore, the phase angle of the tap tool 10 relative to the original line L of the spindle 114 is different from that of the original line L of the spindle 114. o The displacement direction of the tap tool 10 is also different for each threaded hole 6. In order to find the displacement direction, in this embodiment, the tap tool 10 is positioned at the machining start point (not shown) relative to the original line L of the spindle 114. o Then, the control device 120 calculates the phase angle of the tap tool 10 after processing based on the information of the encoder of the spindle motor, and calculates the displacement direction based on the calculated phase angle of the tap tool 10. Figure 6 In the example, the original line L oOn the other hand, since the required displacement amount is determined according to the cross-sectional shape of the tap tool 10 , it is stored in the control device 120 in advance.

[0035] The following describes the use of the tap tool 10 and the Figure 1 An example of tap processing performed by a vertical machine tool as shown.

[0036] Initially, the tap tool 10 is positioned at the machining start point. That is, the rotation axis C of the spindle 114 of the machine tool on which the tap tool 10 is mounted is aligned with the rotation axis C of the spindle 114 of the machine tool. r The tip of the tap tool 10 is positioned at a machining start point at a predetermined height in the Z-axis direction in accordance with the central axis C6 of the pre-drilled hole 6' provided in the workpiece. o The phase angle is set to a specified value.

[0037] Next, the rotation speed of the spindle 114 and the feed speed in the Z-axis direction are synchronized according to the pitch of the thread, and synchronous tapping is performed. When the tap tool 10 moves a predetermined distance in the Z-axis direction and reaches the commanded thread depth, the rotation and feed of the spindle 114 are stopped. Thus, the pre-drilled hole 6' of the workpiece is processed into a threaded hole 6.

[0038] Next, the tap tool 10 is moved in a direction parallel to the rotation axis C. r The above-mentioned specific direction is determined based on the phase angle of the tap tool 10 determined according to the information of the encoder of the spindle motor. Figure 6 In the example, the direction is indicated by the arrow S. The displacement amount uses the value registered in advance in the control device 120. Through this process, the engagement between the threaded portion 14 or the pad portions 15, 16 of the tap tool 10 and the thread groove of the threaded hole 6 is completely released.

[0039] Next, the tap tool 10 is not rotated but is retracted upward to the machining start point. The feed speed of the spindle 114 in the Z-axis direction at this time can be set to be twice or more higher than the feed speed during machining, that is, during forward movement.

[0040] The tapping process of one threaded hole 6 is completed as above.

[0041] According to the present invention, a space 20 is formed between the non-engaging portion 17 of the tap tool 10 and the inner diameter of the threaded hole 6. The space 20 has a space between the tap tool 10 and the rotation axis C. rThe tap tool 10 is a tap tool 10 that is not engaged with the thread groove of the threaded hole 6, and the tap tool 10 is not rotated after the tap tool 10 is disengaged from the thread groove of the threaded hole 6. The tap tool 10 can be pulled out of the threaded hole 6 in the direction of the rotation axis at high speed after machining. Due to the effect of the high-speed pulling, the machining time including the retreat time of the tap tool 10 can be reduced by about 40% compared with the case of using a conventional tap tool 210.

[0042] In addition, according to the present invention, due to the cutting resistance R c The second support portion 16 is supported by the screw hole 6, so the cutting resistance R c The deflection generated in the tap tool 10 is extremely small, and as a result, the processing accuracy is the same as that in the case where a conventional tap tool 210 is used.

[0043] Other Implementations

[0044] The tap tool 10 of the above-described embodiment includes two pads 15 and 16 , but the number of pads is not limited to two. Therefore, in the present invention, for example, the tap tool 10 may include one or three pads.

[0045] The tap tool 10 of the above-mentioned embodiment has the first groove 18 between the first pad portion 15 and the threaded portion 14 , but in the present invention, the tap tool may have no groove between the pad portion and the threaded portion 14 and thus the pad portion and the threaded portion 14 may be formed continuously.

[0046] In the above-mentioned embodiment, the pads 15 and 16 have a radius slightly smaller than the radius of the threaded portion 14 . However, in the present invention, the tap tool 10 may be implemented in which the radius of the pad is equal to the radius of the threaded portion 14 .

[0047] Description of Reference Numerals

[0048] 6 threaded holes;

[0049] 6' pre-drilled;

[0050] 10 tap tools;

[0051] 14 threaded portion;

[0052] 14a blade;

[0053] 14b Anterior tilt surface;

[0054] 15. The first pad part;

[0055] 16. The second pad part;

[0056] 17 non-engaging part;

[0057] 20 Space;

[0058] C6 central axis;

[0059] C r Axis of rotation;

[0060] R c Cutting resistance.

Claims

1. A tap tool having a rotation axis, wherein the pre-drilled hole is processed into a threaded hole in a state where the central axis of a pre-drilled hole provided in a workpiece, the rotation axis and the rotation axis of a spindle on which the tap tool is mounted are aligned, wherein: The above tap tools have: a threaded portion formed asymmetrically with respect to the rotation axis and having a cutting edge portion for machining a thread groove of the threaded hole; a support portion, the support portion being located behind the blade portion in the rotation direction and engaging with the thread groove machined by the blade portion during the machining of the thread groove, rubbing against the surface of the thread groove and supporting the cutting resistance acting on the blade portion; and a non-engaging portion, wherein a space is formed between the non-engaging portion and the threaded hole when viewed in a cross-sectional view so that the rotation axis coincides with the central axis of the threaded hole, The above-mentioned space has the following size: when the tap tool is displaced in the above-mentioned threaded hole in a direction orthogonal to the above-mentioned rotation axis from a state in which the above-mentioned rotation axis is consistent with the above-mentioned center axis of the above-mentioned threaded hole, the engagement between the above-mentioned threaded portion and the above-mentioned threaded groove and the engagement between the above-mentioned pad portion and the above-mentioned threaded groove can be simultaneously released.

2. The tap tool according to claim 1, wherein: The cutting edge portion has a rake surface formed so that cutting resistance generated during tapping is supported by the thread groove via the pad portion.

3. The tap tool according to claim 1, wherein: The above-mentioned pad part is composed of a first pad part and a second pad part. The above tap tool has: a first groove provided between the threaded portion and the first support portion; and The second groove is provided between the first support portion and the second support portion.

4. The tap tool according to claim 1, wherein: The step portion has a radius smaller than a radius of the threaded portion.

5. A tap processing method, using the tap tool according to claim 1, characterized in that: include: The step of aligning the rotation axis of the tap tool with the rotation axis of the main shaft of the machine tool and installing the tap tool on the main shaft; The step of aligning the rotation axis of the spindle of the machine tool equipped with the tap tool with the central axis of the pre-drilled hole provided in the workpiece; a tapping process step, wherein the tapping tool is rotated and moved forward in the direction of the rotation axis to perform tapping process on the pre-drilled hole; a tap tool displacement step of displacing the tap tool in a direction perpendicular to the rotation axis of the spindle so that the threaded portion including the cutting edge of the stationary tap tool is disengaged from the threaded groove of the threaded hole formed in the workpiece; and The step of retreating the tap tool is to retreat the tap tool in the direction of the rotation axis without rotating the tap tool.

6. The tap processing method according to claim 5, wherein: The moving speed of the tap tool in the backward moving step is higher than the moving speed of the tap tool in the forward moving step in the tap processing step.

7. The tap processing method according to claim 5, wherein: After the above tap processing steps, it also includes: A step of calculating the displacement direction of the tap tool in the tap tool displacement step, wherein the displacement direction of the tap tool is calculated based on a phase angle of the tap tool that is stationary after tap machining in the tap machining step around the rotation axis.

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