Tap phase difference detection method, female thread machining method, tap phase difference detection device, and female thread machining device

Abstract

To provide a tap phase difference detection method that detects a phase difference between different taps, by a simple method without using a dedicated device, a female threading method that can execute processing for making phases of the taps match each other, and a device that can execute the methods.SOLUTION: One of taps 4 is defined to be a reference tap 4a, and using a camera 12 that can photograph a contour line of an incomplete thread part 15 provided in the tap 4, in an axial direction of a spindle 2 on which the tap 4 is mounted, the reference tap 4a is positioned at a position where the cameral 12 can photograph the contour line, and then, the camera 12 photographs the contour line; and using the contour line as a reference contour line, another tap 4b is positioned at a position where the contour line can be photographed by the camera 12, and then, the contour line is photographed by the camera 12, and the contour line of the photographed other tap 4b is rotated and a rotation angle of when the contour line matches the reference contour line is obtained as a phase difference between the reference tap 4a and the other tap 4b.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present disclosure relates to a method for detecting a phase difference between different taps, such as when the tap is replaced in a machine tool, a female thread machining method using the method, and an apparatus capable of executing the phase difference detection method and the female thread machining method. [Background technology]

[0002] Taps, which are used to form female threads in workpieces, are prone to various problems. One example is tap breakage. As taps are used to form multiple female threads, their cutting edges gradually wear. This increases the cutting load during processing, and when the cutting load exceeds the tap's allowable load, the tap breaks. Tap breakage can significantly reduce productivity, so it must be prevented. To prevent tap breakage, methods are sometimes used to monitor the cutting load and stop the female threading process. However, once the female threading process is interrupted and the tap is retracted, it is difficult to continue the process with a new tap. Female threading is performed by synchronizing the axial feed and the rotational phase of the tap. Therefore, to continue machining a partially completed female thread with a new tap, the tool extension length and phase of the retracted tap and the new tap must be matched. Contact-type devices for measuring tool length and non-contact devices using laser light are widely used, and tool protrusion length can be easily corrected from the measurement value. Meanwhile, regarding phase, it has traditionally been common for multiple taps not to be phase-aligned with the tool holder. In response to this, methods for determining the phase between the tap and the tool holder have been proposed. For example, Patent Document 1 discloses a tap mounting device that uses a ring gauge and a height gauge to mount a tap on a tap holder at a predetermined phase and protrusion length. Patent Document 2 discloses a machining method that uses a setting gauge to set the relative position of the tap and workpiece. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-39762 [Patent Document 2] Japanese Patent Application Publication No. 2019-93478 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the methods described in Patent Documents 1 and 2 have problems in versatility because they use a dedicated device to determine the phase of the tap and the tool holder. Also, they assume that a series of phase determination tasks will be performed by an operator, which makes automation difficult.

[0005] Therefore, the present disclosure has been made in consideration of the above problem, and aims to provide a tap phase difference detection method that detects the phase difference between different taps in a simple manner without using a dedicated device. Another object of the present disclosure is to provide a female thread machining method that uses the tap phase difference detection method to enable continuous machining of an interrupted female thread. Another object of the present disclosure is to provide a tap phase difference detection device capable of implementing the tap phase difference detection method. Another object of the present disclosure is to provide a female thread machining device that can continue machining of an interrupted female thread using the phase difference detection device of the tap. [Means for solving the problem]

[0006] In order to achieve the above object, a first configuration of the present disclosure is a method for detecting a phase difference between taps, which is a method for detecting a phase difference between a plurality of taps, and is characterized in that a sensor capable of acquiring a contour line of an incomplete thread portion from the incomplete thread portion side of the tap in the axial direction of a main shaft to which the taps are attached is used, and a certain tap is set as a reference tap, and the reference tap is positioned at a position where the contour line can be acquired by the sensor, and the contour line is acquired by the sensor and used as the reference contour line, and another tap is positioned at a position where the contour line can be acquired by the sensor, and the acquired contour line of the other tap is rotated, and the rotation angle when it coincides with the reference contour line is acquired as the phase difference between the reference tap and the other tap. Another aspect of the first configuration of the present disclosure is characterized in that, in the above configuration, the sensor is a camera. Another aspect of the first configuration of the present disclosure is characterized in that, in the above configuration, the sensor is a laser sensor. Another aspect of the first configuration of the present disclosure is characterized in that, in the above configuration, the reference contour line is data of the reference contour line of the reference tap that is acquired in advance by a sensor and stored. Another aspect of the first configuration of the present disclosure is characterized in that, in the above configuration, the reference tap has the same diameter and pitch as the other taps, and the reference contour line is obtained at the start of machining the reference tap. In order to achieve the above object, a second configuration of the present disclosure is a female thread machining method for machining a female thread into a workpiece, characterized in that, using the acquired phase difference, the rotational position of the spindle and / or other rotary axis at the start of machining using another tap is rotated by the phase difference so as to correct the phase difference before machining is performed. In order to achieve the above object, a third configuration of the present disclosure is a tap phase difference detection device that includes a sensor that can acquire the contour line of an incomplete thread portion from the incomplete thread portion side of the tap in the axial direction of a spindle to which the tap is attached, and is characterized in that a certain tap is set as a reference tap, the reference tap is positioned at a position where the contour line can be acquired by the sensor, the contour line is acquired by the sensor, and that contour line is set as the reference contour line, another tap is positioned at a position where the contour line can be acquired by the sensor, the contour line is acquired by the sensor, the acquired contour line of the other tap is rotated, and the rotation angle when it coincides with the reference contour line is acquired as the phase difference between the reference tap and the other tap. Another aspect of the third configuration of the present disclosure is characterized in that, in the above configuration, the sensor is a camera. Another aspect of the third configuration of the present disclosure is characterized in that, in the above configuration, the sensor is a laser sensor. Another aspect of the third configuration of the present disclosure is characterized in that, in the above configuration, the reference contour line is data of the reference contour line of the reference tap that is acquired in advance by a sensor and stored. Another aspect of the third configuration of the present disclosure is characterized in that, in the above configuration, the reference tap has the same diameter and pitch as the other taps, and the reference contour line is obtained at the start of machining the reference tap. In order to achieve the above object, a fourth configuration of the present disclosure is a female thread machining device that machines a female thread on a workpiece, characterized in that the acquired phase difference is used to rotate the rotational position of the spindle and / or other rotating axis at the start of machining using another tap by the phase difference so as to correct the phase difference before performing machining. [Effects of the Invention]

[0007] According to the first and third disclosures of the present invention, the phase difference between taps can be easily detected by rotating the contour lines acquired for each tap and acquiring the rotation angle until the contour lines match as the phase difference. Furthermore, by installing a sensor capable of acquiring the contour line of the incomplete thread portion of the tap in the device, the phase difference between different taps can be detected, eliminating the need for dedicated devices such as gauges that have been used in the past. Additionally, by providing the device with a sensor for detecting the phase difference, the process from detecting the phase difference to starting machining by matching the phase between taps can be automated, thereby improving productivity. According to the second and fourth disclosures of the present invention, the phase difference between different taps can be easily detected, so when interrupted tapping is continued using a replaced tap, or when multiple female threads of the same phase are machined using multiple other taps, the phase of the reference tap can be matched with that of the other taps without the need for complicated work such as using a dedicated device. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is an explanatory diagram showing a main part of a machine tool according to an embodiment. [Figure 2] FIG. 2 is an explanatory diagram showing the shape of a tap. [Figure 3] FIG. 10 is an explanatory diagram showing the relationship between tapping and the camera. [Figure 4] FIG. 10 is an explanatory diagram of an image of a reference tap captured by a camera. [Figure 5] FIG. 10 is an explanatory diagram of an image of another tap captured by a camera. [Figure 6] 1 is a flowchart of a tapping method. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Figure 1 is an explanatory diagram showing the main parts of a machine tool according to an embodiment. Although covers and other equipment are omitted from the machine tool shown in Figure 1, in reality, the machine tool will be equipped with covers and other equipment that are not shown. In Figure 1, the axial direction of a spindle 2 (described later) is defined as the Z-axis direction, the direction perpendicular to the Z-axis and parallel to the paper surface is defined as the X-axis direction, and the direction perpendicular to the Z-axis and also perpendicular to the X-axis, i.e., the direction toward the depth of the paper surface, is defined as the Y-axis direction.

[0010] The machine tool of the embodiment is a machining center M serving as a tapping machine, and as shown in FIG. 1, is equipped with a spindle head 1 capable of motion in three orthogonal axes along the X-axis, Y-axis, and Z-axis. The spindle head 1 is equipped with a rotatable spindle 2, and a tool holder 3 is attached to the tip of the spindle 2. The tool holder 3 holds a tap 4. The machining center M is equipped with an NC device 5 that can control operations including the rotation of the spindle 2 and the feed operation of the spindle head 1. The NC device 5 has functions such as a machine operation control unit 6 that controls the operation of the machining center M, a phase acquisition unit 7, a phase memory unit 8, a phase difference calculation unit 9, and a phase difference correction unit 10. The machining center M uses an NC device 5 to control the rotation of the spindle 2 and the feed motion of the spindle head 1 to machine a female thread with a tap 4 on a workpiece W fixed on a table 11 .

[0011] A camera 12 as a sensor is installed on the table 11 so that the photographing direction is parallel to the Z-axis direction. The camera 12 is connected to the NC device 5, and can be controlled in synchronization with the machining center M.

[0012] FIG. 2 is an explanatory diagram showing the shape of the tap, and illustrates a part of the tap. 2, the tap 4 has a cutting edge 13 that processes a thread into the workpiece W and an axially extending groove 14 for discharging chips from the hole. The cutting edge 13 also has an incomplete thread portion 15 and a complete thread portion 16 that serves as a guide during processing.

[0013] In tapping to form a female thread in a workpiece W, the phase of the female thread is determined by the phase of the tap 4 at the start of processing. The spindle 2 can be positioned at any rotational position by the NC device 5, but the phase when the tap 4 is attached to the tool holder 3 is generally not unique. Therefore, when detecting the phase of the female thread, it is desirable to detect the phase after the tap 4 and tool holder 3 are attached to the spindle 2.

[0014] Next, a method for detecting a phase difference between taps according to the present disclosure will be described. Fig. 3 is an explanatory diagram showing the relationship between the tap and the camera, Fig. 4 is an explanatory diagram of a photographed image of the reference tap, and Fig. 5 is an explanatory diagram of a photographed image of another tap. When detecting the phase of the tap 4, the tap 4 is positioned relative to the camera 12 so that the incomplete thread portion 15 is photographed from the incomplete thread portion 15 side of the tap 4, as shown in Fig. 3. At this time, the tap 4 is positioned so that its axial direction is parallel to the Z axis and so that the outline of the tap 4 as viewed from the axial direction falls within the photographing range of the camera 12, as shown in Figs. 4 and 5. Therefore, by positioning the tap 4 relative to the camera 12 as shown in Fig. 3, the camera 12 can acquire the outline of the cutting portion 13 of the incomplete thread portion 15 as image data, as shown in Figs. 4 and 5. Although the camera 12 is installed on the table 11 in this embodiment, the camera 12 may be installed in a location where it is not affected by cutting water or chips, such as a tool magazine.

[0015] Next, a method for calculating the phase difference between different taps will be described. Here, the explanation will be given assuming that the tap 4 shown in Fig. 4 is a reference tap 4a and the phase difference between the tap 4 and another tap 4b shown in Fig. 5 is to be calculated. First, the reference tap 4a is positioned as described above, and image data of the reference tap 4a's contour line is acquired. The acquired contour line of the reference tap 4a is the reference contour line shown by the two-dot chain line in Figure 4. Next, another tap 4b is positioned as described above, and image data of its contour line is acquired. Because the shape of the incomplete thread portion 15 of the tap 4 varies from one cutting edge to another, the contour line also varies from one cutting edge to another. Therefore, the phase difference between the reference tap 4a and the other tap 4b can be obtained by rotating the image data of the contour line of the other tap 4b shown in Figure 5 and calculating the rotation angle when the image data matches the image data of the reference contour line shown by the two-dot chain line in Figure 5 using the phase difference calculation unit 9. That is, as shown in Figures 4 and 5, based on the contour line and the rotational position of the spindle 2 at the time the contour line was acquired, if the phase of the reference tap 4a (reference phase) is represented as line segment L1 and the phase of the other tap 4b is represented as line segment L2, the angle θ between line segment L1 and line segment L2 is acquired as the phase difference. In the above description, image data of the reference tap 4a captured by the camera 12 is used as the reference contour line. However, data previously stored in the phase storage unit 8 may also be used as the reference contour line. For example, the phase acquisition unit 7 first acquires the phase (reference phase) of the reference tap 4a from the rotational position of the spindle 2 when the reference tap 4a is positioned, and stores the phase acquisition unit 7 in the phase storage unit 8. The phase storage unit 8 then sets a reference contour line based on the design data, such as a drawing of the reference tap 4a, previously stored in the phase storage unit 8, and the stored reference phase, and stores the reference contour line as data. The phase difference between the reference tap 4a and the other taps 4b may be calculated by comparing the data of the reference contour line thus stored with image data of the contour lines of the other taps 4b captured by the camera 12.

[0016] As described above, the phase difference between the taps 4a and 4b can be easily detected by rotating the contour lines acquired for each of the different taps 4a and 4b and acquiring the rotation angle until the contour lines match as the phase difference. Furthermore, by installing a camera 12 capable of acquiring the contour line of the incomplete thread portion 15 of the tap 4 in the machining center M, the phase difference between the different taps 4a and 4b can be detected, eliminating the need for dedicated devices such as gauges that have been used in the past. Additionally, by providing the machining center M with a camera 12 for detecting the phase difference, the process from detecting the phase difference to starting machining by matching the phase between the taps 4a and 4b can be automated, improving productivity.

[0017] Next, a specific tapping method using the machining center M will be described, in particular a method for continuing female thread machining using a replaced tap 4b after the machining using the reference tap 4a was interrupted due to an abnormality or the like during machining. Figure 6 is a flowchart of the tapping method. In the following description of the tapping method, it is assumed that the tool length of the tap 4 is set in advance using a tool setter, a tool presetter, or the like.

[0018] First, the tap 4 is attached to the spindle 2 using the tool holder 3. The tap 4 attached to the spindle 2 first is designated as the reference tap 4a. Based on the set tool length, the reference tap 4a is positioned at a position where the camera 12 can photograph the incomplete thread portion 15. Furthermore, the spindle 2 is indexed to the rotation position at the start of machining. After that, the camera 12 photographs the reference contour line of the reference tap 4a (S1). The rotation position of the spindle 2 when the reference contour line is photographed is the reference position of the spindle 2. Image data of the photographed reference contour line is stored in the phase memory unit 8 together with the reference position.

[0019] After capturing an image of the reference contour line, tapping of the workpiece W is performed using the reference tap 4a (S2). Suppose that, during tapping using the reference tap 4a, machining is subsequently interrupted due to the detection of an abnormality, such as the detection of an increase in cutting load (S3). If the cause of the abnormality is in the tap 4, the reference tap 4a can be replaced with a new tap 4b, allowing machining to continue. Therefore, to resolve the detected abnormality, the reference tap 4a is replaced with another tap 4b that can machine the same diameter and pitch as the reference tap 4a, and the new tap 4b is attached to the spindle 2.

[0020] After the other tap 4b is attached to the spindle 2, it is positioned based on the set tool length at a position where the camera 12 can photograph the incomplete thread portion 15. Thereafter, the camera 12 photographs the contour line of the other tap 4b (S4). Subsequently, the phase difference calculation unit 9 rotates the image data of the contour line of the other tap 4b captured in S4, and calculates the rotation angle when the image data matches the image data of the reference contour line stored in the phase memory unit 8. Then, the rotation angle is acquired as the phase difference between the reference tap 4a and the other tap 4b (S5).

[0021] Thereafter, when the interrupted tapping is resumed using another tap 4b, the phase difference correction unit 10 rotates and corrects the rotational position of the spindle 2 to which the other tap 4b is attached by the phase difference based on the phase difference acquired in S5 so that there is no phase difference with respect to the reference position. Then, tapping is resumed on the workpiece W whose processing was interrupted (S6). This makes it possible to continue tapping in the same phase as the reference tap 4a even when using another tap 4b.

[0022] As described above, since the phase difference between different taps 4a and 4b can be easily detected, when interrupted tapping is continued with the replaced tap 4b, the phase of the reference tap 4a and the other tap 4b can be matched without the need for complicated work such as using a dedicated device.

[0023] The above description of the present disclosure is based on the illustrated examples, and the technical scope of the present disclosure is not limited thereto. For example, the above embodiment shows a method for returning from an interruption when an abnormality is detected during tapping, but the tap phase difference detection method of the present disclosure may be used for other purposes, such as machining multiple female threads of the same phase using multiple other taps. Furthermore, the sensor may be a laser sensor or the like other than a camera, as long as it is capable of acquiring the contour line of the incomplete thread portion of the tap. Furthermore, the rotation axis may be provided on a table other than the main shaft, as long as it is possible to detect the reference position and synchronize the phase between taps. [Explanation of symbols]

[0024] 2··Spindle (rotation axis), 4··Tap, 4a··Reference tap, 4b··Other tap, 12··Camera (sensor), 15··Incomplete thread portion, M··Machining center.

Claims

1. A tap phase difference detection method for detecting a phase difference between a plurality of taps, comprising: Using a sensor capable of acquiring a contour line of the incomplete thread portion from the incomplete thread portion side provided on the tap in the axial direction of the spindle to which the tap is attached, a certain tap is set as a reference tap, and the reference tap is positioned at a position where the contour line can be acquired by the sensor, and then the contour line is acquired by the sensor, and the acquired contour line is set as a reference contour line; Another tap is positioned at a position where the contour line can be acquired by the sensor, and then the contour line is acquired by the sensor; A tap phase difference detection method, characterized by rotating the contour line of the other tap that has been acquired, and acquiring the rotation angle when it coincides with the reference contour line as the phase difference between the reference tap and the other tap.

2. 2. The tap phase difference detection method according to claim 1, wherein the sensor is a camera.

3. 2. The method for detecting a phase difference of a tap according to claim 1, wherein the sensor is a laser sensor.

4. 4. The tap phase difference detection method according to claim 1, wherein the reference contour line is data of the reference contour line of the reference tap that is acquired in advance by the sensor and stored.

5. 4. The tap phase difference detection method according to claim 1, wherein the reference tap has the same diameter and pitch as the other taps, and the reference contour line is acquired at the start of machining the reference tap.

6. A female thread machining method for machining a female thread into a workpiece, comprising:

5. A female thread machining method, comprising: using the phase difference acquired by the tap phase difference detection method according to claim 4, rotating the rotational position of the spindle and / or another rotary axis at the start of machining using the other tap by a phase difference so as to correct the phase difference, and then performing machining.

7. A female thread machining method for machining a female thread into a workpiece, comprising:

6. A female thread machining method, characterized in that, using the phase difference acquired by the tap phase difference detection method according to claim 5, the rotational positions of the spindle and / or another rotary axis at the start of machining using the other tap are rotated by the phase difference so as to correct the phase difference, and then machining is performed.

8. A tap phase difference detection device for detecting a phase difference between a plurality of taps, a sensor capable of acquiring a contour line of the incomplete thread portion from the incomplete thread portion side provided on the tap in the axial direction of the spindle to which the tap is attached; a certain tap is set as a reference tap, the reference tap is positioned at a position where the contour line can be acquired by the sensor, the contour line is acquired by the sensor, and the acquired contour line is set as a reference contour line; After positioning the other tap at a position where the contour line can be acquired by the sensor, the contour line is acquired by the sensor; A tap phase difference detection device characterized by rotating the acquired contour line of the other tap and acquiring the rotation angle when it coincides with the reference contour line as the phase difference between the reference tap and the other tap.

9. 9. The phase difference detection device for a tap according to claim 8, wherein the sensor is a camera.

10. 9. The phase difference detection device for a tap according to claim 8, wherein the sensor is a laser sensor.

11. 11. The phase difference detection device for a tap according to claim 8, wherein the reference contour line is data of the reference contour line of the reference tap that is acquired in advance by the sensor and stored.

12. 11. The tap phase difference detection device according to claim 8, wherein the reference tap has the same diameter and pitch as the other taps, and the reference contour line is acquired at the start of machining of the reference tap.

13. A female thread machining device that performs female thread machining on a workpiece, 12. A female thread machining device characterized in that, using the phase difference acquired by the tap phase difference detection device according to claim 11, the rotational position of the spindle and / or another rotary axis at the start of machining using the other tap is rotated by the phase difference so as to correct the phase difference, and then machining is performed.

14. A female thread machining device that performs female thread machining on a workpiece, 13. A female thread machining device characterized in that, using the phase difference acquired by the tap phase difference detection device according to claim 12, the rotational positions of the spindle and / or another rotary axis at the start of machining using the other tap are rotated by the phase difference so as to correct the phase difference, and then machining is performed.

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