Hole machining methods, control devices and machine tools

Abstract

Hole machining is performed using a tap tool (10), the tap tool being equipped with: a threaded portion (14) that rotates about a rotation axis (Cr) and has a cutting edge (14a) for machining a thread groove in a pre-hole (6′); and a non-locking portion (17) that, in a cross-sectional view aligning the rotation axis (Cr) with the central axis (C6) of the pre-hole (6′), forms a space (20) between itself and the pre-hole (6′), wherein the hole machining includes: machining a thread groove in a pre-hole (6′) with the central axis (C6) and the rotation axis (Cr). In the first state where the axis of rotation (Cr) is aligned, the tap tool (10) is rotated and advanced toward the workpiece (8) to machine the thread groove; by rotating the tap tool (10) around the axis of rotation (Cr), the tap tool (10) moves inside the pre-hole (6′) toward the non-engaged part (17) in a direction orthogonal to the axis of rotation (Cr), and transitions from the first state to the second state where the engagement between the threaded part (14) and the thread groove is released; and the tap tool (10) is withdrawn from the threaded hole (6).

Description

Technical Field

[0001] This invention relates to a hole machining method for machining a pre-hole in a workpiece into a threaded hole, a machine tool control device, and a machine tool. Background Technology

[0002] Patent Document 1 discloses a tap tool (one-way tap) for use with NC (numerical control) milling machines and machining centers. This tap tool has a rotation axis and, when the central axis of a pre-hole provided on a workpiece is aligned with the rotation axis, it processes the pre-hole into a threaded hole. The tap tool is equipped with: a threaded portion having a cutting edge for machining a threaded groove; a flange portion located behind the cutting edge in the rotation direction, which engages with the threaded groove machined by the cutting edge during machining; and a non-engaging portion, which, in a cross-sectional view where the rotation axis is aligned with the central axis of the threaded hole, forms a space between itself and the threaded hole. The key feature is that the space formed between the non-engaging portion and the threaded hole has a size such that, when the tap tool moves within the threaded hole in a direction orthogonal to the rotation axis from a state where the rotation axis is aligned with the central axis of the threaded hole, the engagement of the threaded portion with the threaded groove and the engagement of the flange portion with the threaded groove can be simultaneously released. Therefore, after machining, the tap tool is released from the thread groove of the threaded hole by moving in a direction orthogonal to the axis of rotation. Thus, the tap tool can be pulled out of the threaded hole at high speed in the direction of the axis of rotation without rotating the tap tool, thereby reducing the machining time, including the time to return to the machining start point.

[0003] In such tap tools, like those for general pipe threads, although no so-called stop marks are produced at the end of the thread cut, burrs are easily generated as machining residue. Furthermore, since they can be pulled out without reversing, therefore... Figure 8 As shown, burrs BU sometimes remain at the end of the thread cutting 6E.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent No. 6742468 Specification Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] In view of the above, the object of the present invention is to provide a hole machining method that, in tap machining, prevents burrs from being generated at the end of the thread cutting.

[0009] Methods for solving problems

[0010] According to the present invention, a hole machining method is provided, characterized in that the hole machining is performed using a tap tool, the tap tool being equipped with a threaded portion and a non-engaging portion, the threaded portion rotating about a first axis and having a cutting edge for machining a thread groove in a pre-hole provided in a workpiece, the non-engaging portion forming a space between itself and the pre-hole in a cross-sectional view in which the first axis is aligned with the central axis of the pre-hole, the hole machining comprising: machining a thread groove in the pre-hole in a first state in which the central axis of the pre-hole is aligned with the first axis by advancing the tap tool toward the workpiece side while rotating it; transferring the tap tool from the first state to a second state in which the engagement between the threaded portion and the thread groove is released by moving the tap tool inside the pre-hole toward the non-engaging portion side in a direction orthogonal to the first axis while rotating it about the first axis; and retracting the tap tool along the direction of the central axis of the pre-hole to avoid the threaded hole.

[0011] According to the present invention, a method for machining a threaded hole is provided, characterized in that the hole machining is performed using a tap tool, the tap tool being equipped with a threaded portion and a non-engaging portion, the threaded portion rotating about a first axis serving as a center of rotation, and having a cutting edge for machining a thread groove in a pre-hole provided in a workpiece, the non-engaging portion forming a space between itself and the pre-hole in a cross-sectional view in which the first axis is aligned with the central axis of the pre-hole, the hole machining comprising: in a first state in which the central axis of the pre-hole is aligned with the first axis, machining a thread groove in the pre-hole by advancing the tap tool towards the workpiece while rotating; the tap tool being moved towards the non-engaging portion in a direction orthogonal to the first axis within the pre-hole; and in a second state in which the engagement between the threaded portion and the thread groove is released, moving the tap tool along the central axis of the pre-hole... The direction of the mandrel is moved backward, avoiding the threaded hole. This includes: in a first state, defining a first imaginary circle along the outer circumference of the tap tool; in a second state, defining a second imaginary circle centered on a second axis of the tap tool aligned with the center axis of the pre-hole, smaller than the inner diameter of the pre-hole; and in a cross-sectional view where the second axis aligns with the center axis of the pre-hole, the second imaginary circle includes the tap tool internally and passes near the cutting edge; calculating the intersection point of the first and second imaginary circles, which becomes the intersection point furthest from the cutting edge in the second state; and transferring the tap tool from the first state to the second state by rotating it around a third axis passing through the rotational intersection point and parallel to the first axis; and machining the remaining portion of the thread groove.

[0012] Furthermore, according to the present invention, a control device is provided that controls machining performed using the machining method according to the present invention, wherein the control device has a storage unit that stores the position of the intersection point of rotation on the tap tool relative to a first axis, and the angle at which the tap tool rotates when transitioning from a first state to a second state, associated with each tap tool.

[0013] Furthermore, according to the present invention, a machine tool is provided, the machine tool comprising: a control device according to the present invention; a spindle that holds and rotates a tap tool; and a feed mechanism that moves the spindle relative to the workpiece by means of a Z-axis linear feed section that moves along a first rotation axis, an X-axis linear feed section that moves in a direction orthogonal to the first rotation axis, and a Y-axis linear feed section that moves in a direction orthogonal to both the first rotation axis and the X-axis linear feed section. The machining of thread grooves in a pre-hole is performed by the rotation of the spindle and the relative movement of the Z-axis linear feed section. The transfer of the tap tool from a first state to a second state is achieved by rotating the spindle around a first axis at an angle stored in a storage section, while simultaneously moving the X-axis linear feed section and the Y-axis linear feed section, moving along an arc track with the same radius as a second imaginary circle centered at the intersection of the rotation points.

[0014] The effects of the invention

[0015] According to the processing method of the present invention, by rotating the tap tool inside the pre-hole and moving it towards the non-engaging side in a direction orthogonal to the first axis, a transition can be made from the first state to the second state in which the engagement between the threaded portion of the tap tool and the thread groove is released. From this state, the tap tool is moved (retracted) along the central axis of the pre-hole to avoid the threaded hole. Thus, the tap tool can be pulled out of the threaded hole at high speed. Alternatively, the transition from the first state to the second state can also be made by moving the tap tool around a third axis, which passes through a rotational intersection point that is the intersection of the first imaginary circle in the first state and the second imaginary circle in the second state, and is parallel to the first axis. In this case, since the cutting edge of the threaded portion of the tap tool can move along an arc-shaped track TR, the cutting edge, which has just started rotating from the first state, can move in a sliding manner within the inner circumference of the threaded hole. Thus, the cutting edge can remove burrs that would otherwise be residual parts (incomplete threads) during the machining of the thread groove.

[0016] Furthermore, the control device according to the invention has a storage unit that can store (accommodate) the position of the intersection point of rotation on the tap tool and the angle at which the tap tool rotates when transitioning from the first state to the second state, in association with each tap tool. Therefore, hole machining can be performed at high speed regardless of the size of the tap tool and the threaded hole.

[0017] Furthermore, according to the machine tool of the present invention, for the transfer of the tap tool from the first state to the second state, by rotating the spindle holding the tap tool around the first axis at the angle stored in the storage section, and simultaneously moving the X-axis linear feed section and the Y-axis linear feed section, it can move along an arc track with the same radius as the second imaginary circle, centered on the intersection point of rotation. Therefore, the cutting edge, which has just started rotating from the first state, can slide along the inner circumference of the threaded hole, and the cutting edge can remove burrs during the machining of the thread groove. In addition, since the cutting edge can slide along the inner circumference of the threaded hole by moving the X-axis linear feed section and the Y-axis linear feed section, which are standard features of machine tools, highly versatile hole machining can be performed. Attached Figure Description

[0018] Figure 1 A front view showing the machine tool used in the machining method according to an embodiment of the present invention and the tap tool mounted on the spindle head of the machine tool.

[0019] Figure 2 express Figure 1 A 3D view of a tapping tool.

[0020] Figure 3 express Figure 1 The front view of the tap tool.

[0021] Figure 4 A cross-sectional view showing a tap tool and the threaded hole machined using a tap tool.

[0022] Figure 5 This indicates that the action is performed on Figure 4 The diagram shows the cutting resistance of the tap tool and its main and back components, as well as the cross-sectional view of the tap tool and the threaded hole.

[0023] Figure 6 Indicates the tap tool from Figure 4 The state of rotation and movement is shown in the cross-sectional view of the tap tool and the threaded hole.

[0024] Figure 7 A flowchart illustrating tap machining performed using a machining method according to an embodiment of the present invention.

[0025] Figure 8 A cross-sectional view showing the state of burrs at the end of thread cutting in a tap tool and a threaded hole. Detailed Implementation

[0026] The processing method, machine tool, and control device according to the embodiments will now be described with reference to the accompanying drawings. The same or corresponding elements will be given the same reference numerals, and repeated descriptions will be omitted. For ease of understanding, the scale of the drawings may be changed in some cases.

[0027] Figure 1 The figure shows a machine tool 100 according to the invention, which is a vertical machining center, and a tap tool 10 mounted on the machine tool 100 for machining using the machining method according to the invention. In the figure, arrows indicate the forward and backward direction and the vertical direction of the machine when the machine tool 100 is positioned on a horizontal plane. Y in the figure represents the forward and backward direction (Y-axis direction), and Z represents the vertical direction (Z-axis direction). Furthermore, here, the direction orthogonal to the Y-axis direction in the horizontal plane (relative to...) Figure 1 The direction perpendicular to the paper is called the transverse direction of the machine (X-axis direction).

[0028] The machine tool 100 is equipped with: a machine base 102, which serves as a base fixed to the factory floor; a Y-axis slider 104, which is configured to move along the Y-axis direction on the upper surface of the machine base 102, serving as a Y-axis linear feed unit, on which a workpiece 8, which is not being machined, is clamped and fixed; and a column 108, which extends from the mechanical rear side of the machine base 102. Figure 1 The machine tool 100 is vertically mounted on the upper surface of the right side of the workpiece 8. Furthermore, it is equipped with: an X-axis slider 110, which serves as an X-axis linear feed unit configured to move along the X-axis direction in front of the column 108; a Z-axis slider 112, which serves as a Z-axis linear feed unit configured to move relative to the X-axis slider 110 along the Z-axis direction; and a spindle head 116, which is fixed to the Z-axis slider 112 and rotatably supports the spindle 114 about a rotation axis Cr, which is a first axis along the vertical direction. By configuring the machine tool 100 in this way, the spindle head 116 can move relative to the workpiece 8 and be positioned. In addition, the machine tool 100 is equipped with a control device 120 for controlling the machining performed using the machine tool 100 and an automatic tool changing device (not shown in the figure). The control device 120 has a storage unit 122 and a calculation unit 124. As will be described later, the storage unit 122 is used to store the position (rotation axis Cr) of the rotation center of the tap tool 10 and the rotation angle, and the calculation unit 124 is used to calculate the cutting edge 14a of the tap tool 10 (see reference). Figure 2 The orientation of the tap tool 10 is used to calculate the position of the retraction rotation center Pv, which is the intersection point of the tap tool 10.

[0029] Machine tool 100 performs tapping, also known as synchronous tapping, which means that the rotation of spindle 114 is synchronized with the feed in the Z-axis direction. In this specification, the linear movement in the Z-axis direction used for tapping with tap tool 10 is also referred to as forward movement, and the linear movement in the Z-axis direction used to pull tap tool 10 out of threaded hole 6 is also referred to as backward movement. Furthermore, in this embodiment, since the rotation axis Cr of spindle 114 and the rotation axis Cr of tap tool 10 are always aligned, they are given the same reference numerals in this specification.

[0030] exist Figure 2 The image shows a perspective view of the tap tool 10 according to this embodiment. Figure 3 The center represents the front view. Additionally, in... Figure 4 The middle indicates that the tap tool 10 and the threaded hole 6, which have just been machined, are along... Figure 3 The cross-sectional view of the cut line AA. The tap tool 10 performs tapping with its rotation axis Cr aligned with the central axis C6 of the pre-hole 6' located on the workpiece 8; that is, it is used to form the pre-hole 6' into a threaded hole 6. Figure 4 In the attached drawing, the circle indicated by reference numeral 6a corresponds to the inner diameter of the pre-hole 6' and the threaded hole 6, and the circle indicated by reference numeral 6b corresponds to the diameter of the valley portion of the threaded hole 6, that is, the nominal diameter of the tap tool 10. Furthermore, in Figure 4 In the diagram, Lo represents the crosshair reference line (hereinafter referred to as the "starting line") used to define the rotation angle (phase angle) on the rotation plane of the main spindle 114. Here, in the cross-sectional view, the rotation angle at the 3 o'clock position of the baseline is defined as 0 degrees, and the rotation angles at the 6 o'clock, 9 o'clock, and 12 o'clock positions are defined as 90 degrees, 180 degrees, and 270 degrees, respectively.

[0031] like Figure 2 and Figure 3As shown, the tap tool 10 is equipped with a shank 11 on the base end side and a machining section 12 on the front end side. A taper 13 is provided at the front end of the machining section 12. The machining section 12 has: a male thread-shaped threaded section 14, which is formed asymmetrically with respect to the rotation axis Cr, and has a plurality of cutting edges 14a for machining the threaded groove of the threaded hole 6; male thread-shaped flanges 15 and 16, which engage with the threaded groove machined by the cutting edges 14a; and a non-engaging section 17, which does not contact the pre-hole 6' and the threaded hole 6 during machining. In the threaded section 14, a plurality of thread teeth are formed at intervals of a predetermined pitch in the length direction, and the cutting edges 14a are provided on the front side of each of the plurality of thread teeth in the rotation direction. In this embodiment, the tap tool 10 is a tool for forming a threaded groove of a triangular thread. Furthermore, although the tap tool 10 is described here as a tool for forming a thread groove that forms a triangular thread, it is not limited to this. The tap tool can also be a tool for forming threads of other shapes such as trapezoidal threads and square threads.

[0032] In conventional tap tools, for example, for a threaded portion with a cutting edge, four threaded portions are arranged at 90-degree intervals along the circumference of the tap tool by means of four grooves for the flow of cutting oil extending along the length direction. In contrast, in the tap tool 10 according to this embodiment, only one threaded portion 14 is provided. Figure 4 In the illustrated embodiment, a threaded portion 14 is arranged generally along a direction from 8 o'clock (150 degrees) to 9 o'clock (180 degrees). The cutting edge 14a of the threaded portion 14 operates on the same cutting principle as conventional tap tools, such as... Figure 5 As shown, it has a front 14b. Therefore, threaded grooves can be machined in the same way as with conventional tap tools. Figure 5 In the figure, the cutting resistance Rc, the back component force Rb, and the main component force Rp that act on the front end of the cutting edge 14a of the tap tool 10 as a reaction force against the cutting force during tap machining in the rotation direction T are represented by vectors.

[0033] according to Figure 4The tap tool 10 of this embodiment is configured as a clockwise rotating tool. Flange portions 15 and 16 are formed on the rear side of the threaded portion 14 in the rotational direction. In this embodiment, a first flange portion 15 and a second flange portion 16 are formed as two flange portions. A first groove 18 is formed between the first flange portion 15 and the threaded portion 14, and a second groove 19 is formed between the first flange portion 15 and the second flange portion 16. By means of the first groove 18 and the second groove 19 formed on the front side of the rotational direction of the first flange portion 15 and the second flange portion 16, cutting fluid can be supplied to the flange portions 15 and 16 efficiently. As a result, lubrication between the flange portions 15 and 16 and the workpiece 8 is good, protecting the tap tool 10 and the workpiece 8 from damage caused by friction between the surface of the threaded groove formed by the cutting edge 14a and the flange portions 15 and 16.

[0034] Although male threads are formed in each flange portion 15 and 16 in the same way as in the threaded portion 14, a cutting edge 14a is not formed. In addition, the radius of the male threads in the flange portions 15 and 16 is formed to be slightly smaller than the radius of the male threads in the threaded portion 14, and the degree to which they can engage with the thread groove of the threaded hole 6 formed by the cutting edge 14a of the threaded portion 14 is determined.

[0035] like Figure 5 As shown, flanges 15 and 16 are configured to withstand the cutting resistance Rc generated during machining via the threaded hole 6, preventing the cutting edge 14a from deflecting. The direction of the cutting resistance Rc changes by altering the angle of the front face 14b that abuts (contacts) with the threaded hole 6. In this embodiment, the second flange 16 primarily serves to withstand the cutting resistance Rc. Here, the second flange 16 is formed on the extension line of the direction of action of the cutting resistance Rc acting on the cutting edge 14a. With the aid of the cutting resistance Rc, the machined portion 12, pushed by the cutting edge 14a, is pressed out along the direction of action of the cutting resistance Rc. At this time, the second flange 16 of the pressed-out machined portion 12 abuts against the threaded groove of the threaded hole 6. Thus, the cutting resistance Rc is transmitted to the threaded hole 6. Since the second flange 16 (machined portion 12) is supported by the threaded hole 6, deflection of the cutting edge 14a can be prevented or suppressed.

[0036] like Figure 4 As shown, the non-engaging portion 17 is a curved, smooth surface, formed as a curve connecting points 17a and 17b in a cross-sectional view; in this embodiment, it is formed as an arc. In the tap tool 10 according to this embodiment, since only one threaded portion 14 is provided, a space 20 is formed between the non-engaging portion 17 and the inner diameter of the threaded hole 6. Figure 6As shown, in the state where the machining of the thread groove, which is the first state, is completed, for the thread portion 14 (shown as dashed lines) at the bottom-of-hole stop position where the thread cutting ends at the end 6E, the tap tool 10 rotates clockwise around the retraction rotation axis Cv, which is a third axis passing through the retraction rotation center Pv and parallel to the rotation axis Cr, by a retraction rotation angle θs. As a result, the thread portion 14 (shown as solid lines) rotates and moves from the bottom-of-hole stop position towards the tool retraction possible position (retraction position). Therefore, the space 20 (refer to...) Figure 4 The size is such that the threaded portion 14, the first flange portion 15, and the second flange portion 16, which have rotated and moved towards the retraction position, can move to a position where they are not engaged with the threaded hole 6, allowing the tap tool 10 to retract without reversing. Specifically, the shape of the non-engaging portion 17 is determined according to its relationship with the threaded hole 6 so that a sufficiently large space 20 can be formed. In addition, the size of the space 20 can also be made slightly larger with a margin.

[0037] Furthermore, the space 20 serves as a path for supplying cutting fluid to the cutting edge 14a and for discharging chips generated during cutting, thus improving the quality of the machined surface and extending tool life. Moreover, by forming the non-locking portion 17 into an arc shape, the cross-sectional area of ​​the tap tool 10 can be increased (thickening the tap tool 10), thereby improving the rigidity of the tap machining 10. In the following description, the non-locking portion 17 is described as having an arc shape; however, it is not limited to this. The non-locking portion 17 can also be formed into other shapes, such as a polygon, in the cross-sectional view, provided that the required rigidity is ensured.

[0038] like Figure 6 As indicated by the solid line, the tap tool 10, having been rotated to the retraction position and with the engagement of the threaded portion 14 and the flange portions 15, 16 with the threaded groove released, can be pulled out of the threaded hole 6 by retracting in the direction of the rotation axis Cr. In conventional tap tools, since the engagement with the threaded groove could not be released, it was necessary to reverse the tap tool while pulling it out. In contrast, the tap tool 10 according to this embodiment can be pulled out by retracting without rotation, thus allowing for high-speed retracting.

[0039] Since the required rotational speed of the tap tool 10 varies depending on the depth of the threaded hole 6, the orientation (phase angle on the rotational surface) of the tap tool 10 at the bottom stop position of the hole, where the thread cutting ends at the end of the thread groove 6E, is different for each threaded hole 6. Therefore, the orientation (phase angle on the rotational surface) of the thread cutting end 6E of the tap tool 10, the position of the retraction rotation axis Cv (retraction rotation center Pv), or the possible retraction position of the tool after rotating clockwise by a retraction rotation angle θs around the retraction rotation axis Cv in the cross-sectional view, are also different for each threaded hole 6 (each tap tool 10). Therefore, when the tap tool 10 is positioned at the machining start point (not shown), its origin line Lo relative to the spindle 114 is set at a predetermined phase angle. Thus, the calculation unit 124 calculates the phase angle (on the rotational surface) of the tap tool 10 at the bottom stop position of the machined hole based on this predetermined phase angle and information from the encoder of the spindle 114 motor. Figure 4 In the middle (between 150 and 180 degrees), the retreat rotation angle θs can be calculated based on the calculated phase angle of the tap tool 10.

[0040] The tap tool 10 rotates and moves in the following manner. For example... Figure 6 As shown, in the first state after the thread groove machining is completed, along the tap tool 10 ( Figure 6 The outer periphery of the dashed line in the diagram defines the first imaginary circle VC1. Additionally, in the tap tool 10 ( Figure 6In the second state, where the first imaginary circle VC1 has been rotated towards a predetermined retraction position (as shown by the solid line in the image), a second imaginary circle VC2 is defined. This second imaginary circle VC2 is centered on the axis C2 (second axis) of the tap tool 10, located at a position aligned with the central axis C6 of the pre-hole 6'. Here, the radius of the second imaginary circle VC2 is smaller than the inner diameter of the pre-hole 6', and it is set such that in a cross-sectional view where the axis C2 aligns with the central axis C6 of the pre-hole 6', the tap tool 10 is included on the inside and passes near the cutting edge 14a. Therefore, the first imaginary circle VC1 and the second imaginary circle VC2 intersect at two points (2 locations). The intersection point located on the side furthest from the cutting edge 14a in the second state is taken as the center (retraction rotation center Pv) for transferring (rotating) the tap tool 10 to the second state. Since the second state is defined based on the relationship between the cross-sectional shape of the tap tool 10 and the pre-hole 6', the retraction rotation angle θs varies depending on the cross-sectional shape of the tap tool 10. Therefore, the retraction rotation angle θs can be pre-accommodated (stored) in the storage unit 122 of the control device 120 in association with the tap tool 10. Furthermore, the threaded hole 6, the pitch, and the phase angle of the tap tool 10 at the hole bottom stop position for each tap tool 10 category, as well as the position (X and Y coordinates) of the thread cutting end portion 6E, are also pre-stored in the storage unit 122. In this embodiment, for the first imaginary circle VC1 and the second imaginary circle VC2, the center of the circle is at the same position relative to the tap tool 10, and the first imaginary circle VC1 is a circle centered on the axis C2 in the first state. Additionally, the diameter of the first imaginary circle VC1 is the same as that of the second imaginary circle VC2.

[0041] Below, according to Figure 7 The flowchart shown illustrates an example of tap machining performed using a machine tool 100 equipped with a control device 120 according to this embodiment, employing the machining method according to this embodiment. The tap machining described below is performed by the machine tool 100 operating and machining by implementing macro programs stored in the control device 120 for each tap tool 10. Furthermore, in the following description, tap machining is described based on macro programs prepared individually for the nominal thread size of each thread specification; however, it is not limited to this, for example, it can also be performed using other methods such as instructions from M-codes or G-codes installed on the machine tool 100 (control device 120).

[0042] Initially, a machining program for machining the workpiece is executed. At the location where tap machining is performed in this machining program, a macro program number corresponding to the desired nominal thread size is recorded. In step S10, in the control device 120, when the macro program for tap machining in the machining program is executed to the recorded location, the macro program number corresponding to the nominal thread size is specified, and a macro program is retrieved with the machining start point at a specified position (height) in the Z-axis direction, the depth of the threaded hole 6, the rotational speed of the spindle 114, and the position (X coordinate, Y coordinate) of the pre-hole 6' as independent variables. Specifically, for example, in the machining program, G65 P0061 X100 Y100 R-100Z20 S100 is recorded. Here, G65 represents the macro retrieval command used in the NC (numerical control device) machining program, P is the retrieved macro program number, X represents the X coordinate of the hole center, Y represents the Y coordinate of the hole center, R represents the machining start point in the Z coordinate, Z represents the length in the Z coordinate direction for thread machining, and S represents the spindle rotational speed (refer to...). Figure 6 These independent variables, unlike the parameters described later, are used by the operator of the machine tool 100 to specify the desired values. At this time, the processing of the macro program invoked in either the absolute coordinate system (e.g., G90: absolute command) or the relative coordinate system (e.g., G91: incremental command) is confirmed by obtaining the state of the mode set in the control device 120. The processing (steps) of the following macro program differ depending on whether the coordinate values ​​are based on the absolute or relative coordinate system, but the processing content itself is the same.

[0043] Next, in step S20, parameters that have been pre-inputted and stored in the storage unit 122 of the control device 120 are read from the macro program. Specifically, the parameters are the position (X-coordinate, Y-coordinate) of the end portion 6E of the thread cutting, the position (X-coordinate, Y-coordinate) of the retraction rotation center Pv, the retraction rotation angle θs, the pitch, etc. Since these parameters vary depending on the diameter and pitch of the thread, it is necessary to store the parameters separately for each nominal size of the thread. In this embodiment, parameters corresponding to each macro program are pre-stored. Alternatively, these parameters may not be input but are directly written into the macro program itself beforehand. In addition, the feed rate in the Z-axis direction (forward direction) is calculated based on the rotational speed of the spindle 114 and the pitch.

[0044] Next, in step S30, the tap tool 10 is positioned (moved) to the machining start point at a predetermined position (height) in the Z-axis direction. That is, the rotation axis Cr of the spindle 114 of the machine tool on which the tap tool 10 is mounted is aligned with the central axis C6 of the pre-hole 6' formed on the workpiece 8, and the tip of the tap tool 10 is moved (lowered) and positioned at the machining start point. At this time, the phase angle of the tap tool 10 relative to the starting line Lo of the spindle 114 is set to a predetermined value.

[0045] Next, in step S40, the rotational speed of the spindle 114 and the calculated feed rate in the forward direction are synchronized with the pitch to perform synchronous tapping. The tap tool 10 moves a specified distance in the Z-axis direction to reach the commanded thread depth, and then the rotation and feed (forward movement) of the spindle 114 are stopped. Thus, the pre-hole 6' of the workpiece is machined into a threaded hole 6.

[0046] Next, in step S50, the tap tool 10 rotates around the retraction rotation axis Cv by a retraction rotation angle θs. Specifically, the tap tool 10 rotates the spindle 114 around the rotation axis Cr by the retraction rotation angle θs stored in the storage unit 122. At the same time, by moving the X-axis slider 110 and the Y-axis slider 104, the tap tool 10 transitions from the first state to the second state along an arc TR with the same radius as the second imaginary circle VC2, centered on the retraction rotation center Pv. Figure 6 (See arrow S in the image). Thus, the engagement between the threaded portion 14, flange portions 15, and 16 of the tap tool 10 and the threaded groove of the threaded hole 6 is completely released. Furthermore, by rotating the tap tool 10 around the retraction rotation axis Cv by a retraction rotation angle θs, its cutting edge 14a moves along an arc-shaped track TR. Therefore, the cutting edge 14a, having just begun rotating from the first state, moves in a sliding manner within the inner circumference of the threaded hole 6. Thus, the cutting edge 14a can remove (machine away) burrs BU that would become residual portions (incomplete threads) in the threaded groove machining (see reference). Figure 8 ).

[0047] Next, in step S60, the tap tool 10 moves backward upwards without rotating to the machining start point. The feed rate of the spindle 114 in the Z-axis direction during the backward movement can be more than twice as high as the feed rate during machining, i.e., during forward movement. With these steps, the tapping of a threaded hole 6 is completed.

[0048] According to this embodiment, by moving the tap tool 10 inside the pre-hole 6' towards the non-engaging portion 17 in a direction orthogonal to the rotation axis Cr, the tap tool 10 can be transferred from a first state to a second state in which the engagement between the threaded portion 14 of the tap tool 10 and the thread groove is released. From this state, the tap tool 10 is moved along the central axis C6 of the pre-hole 6' and withdrawn from the threaded hole 6. Thus, the tap tool 10 can be pulled out of the threaded hole 6 at high speed. Furthermore, the transfer from the first state to the second state can be performed by rotating the tap tool 10 around the withdrawal rotation axis Cv, which passes through the withdrawal rotation center Pv, which is the intersection of the first imaginary circle VC1 in the first state and the second imaginary circle VC2 in the second state, and is parallel to the rotation axis Cr. At this time, since the cutting edge 14a of the threaded portion 14 of the tap tool 10 can move along the arc-shaped track TR, the cutting edge 14a, after just starting to rotate from the first state, can move in a sliding manner within the inner circumference of the threaded hole 6. Therefore, the cutting edge 14a can remove burrs BU that would become machining residues (incomplete thread portions) in the thread groove machining. The above describes the tap tool 10 moving towards the non-engaging portion 17 side inside the pre-hole 6' in a direction orthogonal to the rotation axis Cr (horizontal direction). However, since the thread groove is a helix with a specified pitch, when the tap tool 10 rotates around the retraction rotation axis Cv, a synchronous movement occurs that causes the tap tool 10 to advance in a direction parallel to the rotation axis Cr, consistent with the pitch.

[0049] Furthermore, according to this embodiment, the control device 120 for controlling machining has a storage unit 122 that can store, in association with each tap tool 10, the position of the retraction rotation center Pv on the tap tool 10, and the retraction rotation angle θs that causes the tap tool 10 to rotate when transitioning from the first state to the second state. Therefore, hole machining can be performed at high speed regardless of the size of the tap tool 10 and the threaded hole 6.

[0050] Furthermore, according to this embodiment, the transition from the first state to the second state of the tap tool 10 allows the spindle 114 of the tap tool 10 to rotate around the rotation axis Cr at a retraction rotation angle θs stored in the storage unit 122, while simultaneously moving the X-axis slider 110 and the Y-axis slider 104. This allows the tool to move along an arc TR with the same radius as the second imaginary circle VC2, centered on the retraction rotation center Pv. Therefore, the cutting edge 14a, which has just begun rotating from the first state, can slide along the inner circumference of the threaded hole 6, and the cutting edge 14a can remove burrs BU during thread groove machining. Additionally, since the X-axis slider 110 and the Y-axis slider 104 can be moved using the arc complementation command, which is standardly provided in the control device 120 of the machine tool 100, and the cutting edge 14a can slide along the inner circumference of the threaded hole 6, highly versatile hole machining can be performed.

[0051] According to the above description, the processing method of this embodiment can prevent burrs (BU) from being generated at the end of the thread cutting during tap processing.

[0052] Furthermore, the tap tool 10 of this embodiment is described as having two flange portions 15 and 16. However, it is not limited to this and the tap tool may also have one or more flange portions.

[0053] Furthermore, the tap tool 10 of this embodiment describes the case where a first groove 18 is formed between the first flange portion 15 and the threaded portion 14. However, it is not limited to this. It is also possible that the groove is not formed between the flange portion and the threaded portion, so that the flange portion and the threaded portion 3 are formed continuously.

[0054] Furthermore, in this embodiment, it is described that the flange portions 15 and 16 have radii that are slightly smaller than the radius of the threaded portion 14. However, it is not limited to this, and the radius of the flange portion and the radius of the threaded portion can also be formed to be equal.

[0055] Explanation of reference numerals in the attached figures

[0056] 6 threaded holes

[0057] 6' Pre-hole

[0058] 8. Workpiece (workpiece)

[0059] 10 taps

[0060] 14 Threaded section

[0061] 14a blade

[0062] 17 Non-card joint section

[0063] 20 spaces

[0064] 100 machine tools

[0065] 104 Y-axis slider (Y-axis linear feed unit)

[0066] 110X-axis slider (X-axis linear feed unit)

[0067] 112 Z-axis slider (Z-axis linear feed unit)

[0068] 114 spindle

[0069] 120 control device

[0070] 122 Storage Department

[0071] 124 Computing Department

[0072] BU burrs (machining residue)

[0073] C2 axis (second axis)

[0074] C6 central axis

[0075] Cr rotation axis (first axis)

[0076] Cv retraction rotation axis (third axis)

[0077] Pv avoids the center of rotation (intersection point for rotation)

[0078] VC1 First Imaginary Circle

[0079] VC2 Second Imaginary Circle

[0080] θs retreat rotation angle

Claims

1. A method for machining holes, characterized in that, Hole machining is performed using a tap tool equipped with a threaded portion and a non-engaging portion. The threaded portion rotates about a first axis and has a cutting edge for machining a thread groove in a pre-hole provided in a workpiece. The non-engaging portion forms a space between itself and the pre-hole in a cross-sectional view in which the first axis coincides with the central axis of the pre-hole. The hole machining includes: In a first state where the central axis of the pre-hole is aligned with the first axis, a thread groove is machined in the pre-hole by rotating the tap tool while advancing it toward the workpiece. By rotating the tap tool around the first axis by an avoidance rotation angle (θs) while simultaneously moving the tap tool inside the pre-hole toward the non-engaged portion in a direction orthogonal to the first axis, the tap tool is transferred from this first state to a second state in which the engagement between the threaded portion and the threaded groove is released, thereby machining the remaining portion of the threaded groove; and The tap tool is moved back along the central axis of the pre-hole to avoid the threaded hole.

2. A method for machining a threaded hole, characterized in that, Hole machining is performed using a tap tool equipped with a threaded portion and a non-engaging portion. The threaded portion rotates about a first axis serving as a center of rotation and has a cutting edge for machining a thread groove in a pre-hole provided in a workpiece. The non-engaging portion forms a space between itself and the pre-hole in a cross-sectional view in which the first axis coincides with the central axis of the pre-hole. The hole machining includes: In a first state where the central axis of the pre-hole is aligned with the first axis, a thread groove is machined in the pre-hole by rotating the tap tool while advancing it toward the workpiece. The tap tool is moved inside the pre-hole toward the non-engaging portion in a direction orthogonal to the first axis. In a second state, where the engagement between the threaded portion and the threaded groove is released, the tap tool is retracted along the central axis of the pre-hole, thus avoiding the threaded hole. The hole machining method further includes: In the first state, a first imaginary circle is drawn along the outer circumference of the tap tool. In the second state, a second imaginary circle is defined. This imaginary circle is centered on the second axis of the tap tool, which coincides with the central axis of the pre-hole. It is smaller than the inner diameter of the pre-hole, and in a cross-sectional view aligning the second axis with the central axis of the pre-hole, the second imaginary circle includes the tap tool internally and passes near the cutting edge. The intersection point of the first imaginary circle and the second imaginary circle is calculated as the intersection point on the side furthest from the cutting edge in the second state, which is used for rotation. By rotating the tap tool around a third axis that passes through the intersection of the rotation and is parallel to the first axis, the tap tool is transferred from the first state to the second state, and the remaining portion of the thread groove is machined.

3. The hole machining method as described in claim 2, characterized in that, Also includes: Based on the depth to which the tap tool is inserted into the pre-hole, calculate the orientation of the cutting edge on the rotational plane of the tap tool about the first axis when the thread groove is finished being machined in the pre-hole. Calculate the position of the intersection point for rotation of the tap tool.

4. The hole machining method as described in claim 2, characterized in that, The non-engaging portion of the tap tool is an arc shape that is internally tangent to and overlaps with the first imaginary circle and / or the second imaginary circle in a cross-sectional view.

5. A control device that controls machining performed using the hole machining method as described in any one of claims 2 to 4, wherein, The control device has a storage unit that stores the position of the rotational intersection point on the tap tool relative to the first axis, and the angle at which the tap tool rotates when transitioning from the first state to the second state, associated with each tap tool.

6. A machine tool, comprising: The control device as described in claim 5; Spindle, which holds and rotates the tap tool; and The feed mechanism, by means of a Z-axis linear feed unit that moves along a first rotation axis, an X-axis linear feed unit that moves in a direction orthogonal to the first rotation axis, and a Y-axis linear feed unit that moves in a direction orthogonal to both the first rotation axis and the X-axis linear feed unit, moves the spindle relative to the workpiece. The threaded groove is machined in the pre-hole by the rotation of the spindle and the relative movement of the Z-axis linear feed unit. The transition of the tap tool from the first state to the second state is as follows: the spindle is rotated around the first axis at an angle stored in the storage section, while the X-axis linear feed section and the Y-axis linear feed section are moved, moving along an arc track with the same radius as the second imaginary circle, centered on the intersection point of the rotation.

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