Screw thread inspection device

Abstract

The present invention provides a thread inspection device that can prevent damage to the gauge or the female thread during thread inspection of the female thread using a gauge. [Solution] The screw thread inspection device 1, when the control unit 50 detects that the contact detection unit 40 has come into contact with the screw gauge 11 and the chamfered portion 61 of the female thread 60, rotates the screw gauge 11 with the gauge moving unit 20 and maintains the contact state between the screw gauge 11 and the chamfered portion 61 of the female thread 60. When the starting position of the screw thread of the screw gauge 11 and the starting position of the screw thread of the female thread 60 coincide and the screw gauge 11 is screwed into the female thread 60 to a predetermined depth, the gauge moving unit 20 causes the screw gauge 11 to rotate and move in accordance with the lead of the screw gauge 11.

Description

Technical Field

[0001] The present invention relates to a thread inspection device capable of preventing scratches or the like from occurring on a thread gauge or an internal thread during the thread inspection of the internal thread by the thread gauge.

Background Art

[0005] In the thread inspection device described in Patent Document 1 above, when the limit gauge held in the gauge tool descends to a predetermined position above the female thread, the moving motor is driven by the thrust parameter and velocity parameter used during the thread inspection of the female thread. As a result, the gauge tool descends from the predetermined position above the female thread and is controlled to descend at a speed equal to the screwing speed of the limit gauge into the female thread, which is determined by the rotational speed of the limit gauge and the lead of the female thread, until the go and no-go inspections are completed.

[0006] As described above, the thread inspection device described in Patent Document 1 screws the limit gauge in at a constant screwing speed from a predetermined position above the female thread to the stop inspection end position. As a result, even after the limit gauge and the chamfered part of the female thread come into contact, the chamfered part continues to be pressed by the thrust and speed parameters used during the thread inspection, which can cause distortion of the limit gauge and damage or distortion to the chamfered part and threads of the female thread.

[0007] The present invention was made to solve the above problems, and aims to provide a thread inspection device that can prevent scratches or other damage to the gauge or female threads when inspecting the threads of female threads using a gauge. [Means for solving the problem]

[0008] The screw thread inspection device according to the present invention comprises a screw gauge having at least a male thread portion formed on its tip side, a gauge moving unit that supports the screw gauge so as to be rotatable around the screw axis and so as to be reciprocally movable in the direction of the screw axis, a control unit that controls the rotation and reciprocating movement of the screw gauge by the gauge moving unit, a torque detection unit that can detect the torque applied to the screw gauge, and a contact detection unit that can detect when the screw gauge comes into contact with the chamfered portion of the female thread on the object to be inspected. When the contact detection unit detects that the screw gauge and the chamfered portion of the female thread have come into contact, the control unit rotates the screw gauge using the gauge moving unit and maintains the contact state between the screw gauge and the chamfered portion of the female thread. When the starting position of the screw thread of the screw gauge and the starting position of the screw thread of the female thread coincide and the screw gauge is screwed into the female thread to a predetermined depth, the gauge moving unit causes the screw gauge to rotate and move in accordance with the lead of the screw gauge.

[0009] Thus, in this invention, when the contact detection unit detects that the screw gauge has come into contact with the chamfered portion of the female thread on the object to be inspected, the control unit rotates the screw gauge using the gauge moving unit based on the detection by the contact detection unit, and maintains the contact state between the screw gauge and the chamfered portion of the female thread. As a result, the screw gauge is rotated until the starting position of the screw thread on the screw gauge coincides with the starting position of the screw thread on the female thread, without applying a dynamic load to the chamfered portion of the female thread. This prevents scratches on the screw gauge and the female thread caused by contact between the screw gauge and the female thread.

[0010] The screw thread inspection device according to the present invention, if necessary, has a control unit that applies a static load to the chamfered portion of the female thread, which allows the screw gauge to descend in the depth direction of the female thread, when the starting position of the screw thread of the screw gauge coincides with the starting position of the screw thread of the female thread, thereby maintaining contact with the female thread.

[0011] Thus, in this invention, since a static load is applied to the chamfered portion of the female thread when the screw gauge and the chamfered portion of the female thread are in contact, excessive load is not applied to the chamfered portion of the female thread until the threads of the screw gauge and the threads of the female thread engage, thereby preventing scratches and other damage to the screw gauge and the female thread.

[0012] The screw thread inspection device according to the present invention, if necessary, when the torque detected by the torque detection unit exceeds a threshold, the control unit rotates and moves the screw gauge in the depth direction of the female thread in the object to be inspected, based on the amount of movement of the screw gauge by the gauge moving unit.

[0013] Thus, in this invention, the control unit rotates and moves the screw gauge in the depth direction of the female thread in the object to be inspected based on the amount of movement of the screw gauge by the gauge moving unit. As a result, the control unit can control the rotation and reciprocating movement of the gauge moving unit based on the amount of movement of the screw gauge, and the threads of the female thread in the object to be inspected can be inspected without stopping the device, even if the screw gauge does not come into contact with the chamfered portion of the female thread. [Brief explanation of the drawing]

[0014] [Figure 1] This is a schematic diagram of a screw thread inspection device according to the first embodiment of the present invention. [Figure 2] This is a schematic diagram showing another example of a thread inspection device according to the first embodiment of the present invention. [Figure 3] This is a flowchart showing the operation of a screw thread inspection device according to the first embodiment of the present invention. [Figure 4] This is a schematic diagram showing the movement of a screw gauge in a screw thread inspection device according to the first embodiment of the present invention. [Figure 5] This is a schematic diagram showing the movement of a screw gauge in a screw thread inspection device according to the first embodiment of the present invention. [Figure 6]It is a schematic diagram showing the movement of a thread gauge in a thread inspection device according to the first embodiment of the present invention. [Figure 7] It is a flowchart showing the operation of a thread inspection device according to the second embodiment of the present invention.

Mode for Carrying Out the Invention

[0015] (First Embodiment of the Present Invention) Hereinafter, a thread inspection device according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 6. Throughout this embodiment, the same elements are denoted by the same reference numerals.

[0016] As shown in FIG. 1, the thread inspection device 1 according to this embodiment includes an inspection unit 10 having a thread gauge 11, a gauge moving unit 20 that supports the inspection unit 10 so as to be rotatable around the thread axis of the thread gauge 11 and reciprocally movable in the thread axis direction, a torque detection unit 30 that can detect the torque applied to the thread gauge 11, a contact detection unit 40 that can detect that the tip of the thread gauge 11 has come into contact with the inspection object W, and a control unit 50 that controls the rotation and reciprocation of the thread gauge 11 by the gauge moving unit 20.

[0017] A female thread 60 is formed on the inspection object W, and the thread inspection device 1 inspects the thread accuracy and the like of this female thread 60. This inspection object W is fixed at a predetermined position by being clamped, for example, from four directions by a slide unit 70 during inspection by the thread inspection device 1.

[0018] The female thread 60 of the inspection object W is manufactured by forming a pilot hole by center hole machining and drilling a pilot hole, chamfering, and then forming a thread by tapping. Therefore, a chamfered portion 61 that slopes so as to reduce the diameter in the depth direction from the surface of the inspection object W is formed at the opening of the female thread 60 into which the male thread is inserted when the inspection object W is used. A threaded portion 62 having a thread that meshes with the thread of the thread gauge 11 is formed continuously with the chamfered portion 61 on the female thread 60.

[0019] The inspection unit 10 includes a screw gauge 11 having at least a male thread portion 12 formed on the tip side, and a gauge fixing portion 13 that supports and fixes the screw gauge 11 on its base end side.

[0020] The screw gauge 11 has at least a male thread portion 12 formed on its tip side, and with this male thread portion 12, it is possible to determine whether the threads of the female thread 60 in the inspection object W are good or bad. The tip of the screw gauge 11 is generally a flat surface. For example, when the effective diameter of the female thread 60 is smaller than the reference value and is formed within the minimum tolerance, the threads of the male thread portion 12 and the threads of the female thread 60 interfere with each other and the torque increases (torque up). When the detected torque at this time exceeds a preset limit torque, the female thread 60 is determined to be defective.

[0021] The gauge moving unit 20 includes a rotation drive unit 21 that supports the inspection unit 10 so as to be rotatable around the screw axis of the screw gauge 11, and a reciprocating movement unit 22 that supports the inspection unit 10 so as to be reciprocally movable in the screw axis direction of the screw gauge 11. The rotation drive unit 21 is, for example, an electric motor disposed coaxially with the screw gauge 11, and the reciprocating movement unit 22 can be, for example, a ball screw mechanism disposed parallel to the screw axis of the inspection unit 10 and an electric motor or the like coaxially connected to the ball screw mechanism.

[0022] The torque detection unit 30 detects the rotational torque applied to the screw gauge 11 of the inspection unit 10 rotationally driven by the rotation drive unit 21.

[0023] The contact detection unit 40 is connected to the reciprocating movement unit 22 and detects that the screw gauge 11 of the inspection unit 10 lowered by the reciprocating movement unit 22 has come into contact with the chamfered portion 61 of the female thread 60 in the inspection object W. Contact between the screw gauge 11 and the chamfered portion 61 of the female thread 60 is detected, for example, based on the distance from the initial position of the tip of the screw gauge 11 to the contact position between the screw gauge 11 and the chamfered portion 61 of the female thread 60, and the amount of movement of the screw gauge 11 by the reciprocating movement unit 22. Alternatively, for example, if the reciprocating movement unit 22 is configured using a ball screw mechanism, contact may be detected by the torque increase detected by the reciprocating movement unit 22 as a result of contact between the screw gauge 11 and the chamfered portion 61 of the female thread 60. In other words, the torque detection unit 30 may also serve as the contact detection unit 40.

[0024] Furthermore, as shown in Figure 2, the contact detection unit 40 may be integrally configured with the inspection unit 10. In this case, the contact detection unit 40 is composed of a sensor such as a force sensor, and for example, the force sensor detects the force applied to the screw gauge 11 in the screw axis direction due to the contact between the screw gauge 11 and the chamfered portion 61 of the female screw 60, thereby detecting contact.

[0025] The control unit 50 controls the rotation and reciprocating movement of the screw gauge 11 by the rotation drive unit 21 and the reciprocating movement unit 22 of the gauge moving unit 20, according to the height position of the inspection unit 10 (tip of the screw gauge 11) and the shape of the lead of the female thread 60 of the object to be inspected W. Furthermore, the control unit 50 controls the rotation and stopping operations of the screw gauge 11 by the rotation drive unit 21 in accordance with the torque detected by the rotation drive unit 21, which is sent from the torque detection unit 30. Furthermore, when the contact detection unit 40 detects contact between the screw gauge 11 and the chamfered portion 61 of the female screw 60, the control unit 50 stops the movement of the inspection unit 10 in the depth direction of the female screw 60 by the reciprocating movement unit 22, and rotates the screw gauge 11 with the rotation drive unit 21 while maintaining the contact state between the screw gauge 11 and the chamfered portion 61 of the female screw 60.

[0026] Next, the operation of the thread inspection device according to this embodiment will be explained using Figures 3 to 6. Figure 3 is a flowchart showing the operation of the thread inspection device according to this embodiment, and Figures 4 to 6 are schematic diagrams for explaining the operation of the thread inspection device according to this embodiment.

[0027] First, as shown in Figure 4, the object to be inspected W, which is fixed to the slide section 70, is moved by a moving mechanism (not shown) to move the female thread 60 of the object to be inspected W downwards to the thread inspection device 1. At this time, the thread axis of the threaded portion 62 in the female thread 60 and the thread axis of the thread gauge 11 of the inspection section 10 are coaxial.

[0028] When the object to be inspected W is set in a predetermined position, the control unit 50 operates the reciprocating movement unit 22 to lower the inspection unit 10 toward the object to be inspected W at a predetermined speed (step S10). The lowering speed of the screw gauge 11 at this time may be constant until the screw gauge 11 comes into contact with the chamfered portion 61 of the female thread 60, or, from the viewpoint of preventing damage to the screw gauge 11 or the female thread 60, the speed may be reduced just before the screw gauge 11 comes into contact with the female thread 60.

[0029] As the screw gauge 11 descends, as shown in Figure 5, when the contact detection unit 40 detects contact between the screw gauge 11 and the chamfered portion 61 of the female thread 60 (step S20: YES), the control unit 50 stops the reciprocating unit 22 and activates the rotation drive unit 21 to rotate the screw gauge 11 in the direction in which the threads of the screw gauge 11 and the threads of the female thread 60 engage, thereby maintaining the contact state between the screw gauge 11 and the chamfered portion 61 (step S30). In step S30, the contact state is maintained by applying a static load to the chamfered portion 61 of the female thread 60, such as a static load approximately equal to the weight of the screw gauge 11, which allows the screw gauge 11 to descend in the depth direction of the female thread 60 when the starting position of the threads of the screw gauge 11 and the starting position of the threads of the female thread 60 coincide. This static load may be controlled by the control unit 50 to apply any desired static load, or the weight of the screw gauge 11 may be applied to the chamfered portion 61 of the female thread 60 by releasing the restriction on the vertical movement of the screw gauge 11 in the screw axis direction while only the height position of the gauge fixing part 13 supporting the screw gauge 11 is maintained. On the other hand, if the contact detection unit 40 does not detect contact between the screw gauge 11 and the chamfered portion 61 of the female screw 60 (step S20: NO), the reciprocating movement unit 22 continues to lower the inspection unit 10 until contact is detected.

[0030] Next, the control unit 50 detects the contact detection unit 40's displacement of the screw gauge 11 in the depth direction, that is, when the starting position of the threads on the screw gauge 11 and the starting position of the threads on the female thread 60 coincide in a plan view, and the screwing of the screw gauge 11 and the female thread 60 begins (step S40: YES), as shown in Figure 6, the gauge moving unit 20 rotates and moves the screw gauge 11 in the depth direction of the female thread 60 according to the lead of the female thread 60 (step S50). At this time, the control unit 50 determines that the screw gauge 11 has been screwed into the female thread 60 when the screw gauge 11 has been screwed to a predetermined depth, and rotates and moves (lowers) the screw gauge 11 according to the lead using the gauge moving unit 20. Here, the predetermined depth is, for example, when the pitch of the screw gauge 11 is 1.25 mm, the control unit 50 determines that the threads of the screw gauge 11 and the threads of the female thread 60 have been screwed together when the screw gauge 11 has been lowered 2 mm in the depth direction of the female thread 60.

[0031] If the torque detected by the torque detection unit 30 during the rotation and lowering of the screw gauge 11 is below a preset threshold (step S60: YES), the control unit 50 continues to rotate and lower the screw gauge 11 using the gauge moving unit 20. When the screw gauge 11 is screwed to a preset depth (step S70: YES), the gauge moving unit 20 reverses and raises the screw gauge 11 (step S80), withdrawing the screw gauge 11 from the female thread 60, and ending the inspection of the female thread 60 by the screw thread inspection device 1. If the screw gauge 11 has not reached the predetermined depth of the female thread 60 (step S70: NO), the rotation and lowering of the screw gauge 11 by the gauge moving part 20 continues.

[0032] In step S60, for example, if the effective diameter of the female thread 60 is smaller than the reference value and is formed within the minimum tolerance, and the torque detected by the torque detection unit 30 exceeds the threshold (step S60: NO), the control unit 50 stops the rotation and lowering of the screw gauge 11 by the gauge moving unit 20 (step S90), and ends the inspection of the female thread 60. After the rotation and lowering of the screw gauge 11 is stopped, the screw gauge 11 is rotated in the opposite direction and raised manually or automatically to remove the screw gauge 11 from the female thread 60.

[0033] In this way, the contact detection unit 40 detects when the screw gauge 11 comes into contact with the chamfered portion 61 of the female thread 60 in the object to be inspected W, and the control unit 50, when the contact detection unit 50 detects that the screw gauge 11 and the chamfered portion 61 of the female thread 60 have come into contact, rotates the screw gauge 11 with the gauge moving unit 20 and maintains the contact state between the screw gauge 11 and the chamfered portion 61 of the female thread 60. As a result, the screw gauge 11 is rotated until the starting position of the screw threads of the screw gauge 11 and the starting position of the screw threads of the female thread 60 coincide, without applying a dynamic load to the chamfered portion 61 of the female thread 60. This prevents scratches and other damage to the screw gauge 11 and the female thread 60 caused by contact between the screw gauge 11 and the female thread 60.

[0034] Furthermore, when the screw gauge 11 and the chamfered portion 61 of the female thread 60 are in contact, a static load is applied to the chamfered portion 61 of the female thread 60. This prevents excessive load from being placed on the chamfered portion 61 of the female thread 60 until the threads of the screw gauge 11 and the threads of the female thread 60 are screwed together, thereby preventing scratches and other damage to the screw gauge 11 and the female thread 60.

[0035] In the above embodiment, a standard screw gauge in which the male thread portion 12 is a through thread portion was used as an example of the screw gauge 11, but it is not limited to this, and a limit gauge in which the male thread portion 12 has both a through thread portion and a no-go thread portion may also be used. Furthermore, instead of plug gauges such as these standard screw gauges and limit gauges, the screw gauge can also be a ring gauge for inspecting the male threads formed on the object to be inspected W.

[0036] (Second embodiment of the present invention) In the screw thread inspection device according to the first embodiment described above, when the contact detection unit detects contact between the screw gauge and the female thread, the device is configured to maintain the contact state between the screw gauge and the chamfered portion of the female thread by operating only the rotation drive unit. However, the device is not limited to this configuration, and as shown in Figure 7, it is also possible to configure the device to rotate and move the screw gauge in the depth direction of the female thread in the object to be inspected by the gauge movement unit based on the amount of movement of the screw gauge.

[0037] In the first embodiment described above, the threads of the threaded portion 62 of the female thread 60 are inspected after the thread gauge 11 has come into contact with the chamfered portion 61 of the female thread 60. However, there are cases where the thread gauge 11 and the chamfered portion 61 of the female thread 60 do not come into contact, and the thread starting position of the thread gauge 11 moves to face the thread starting position of the female thread 60, before descending to the threaded portion 62 of the female thread 60, making it possible to screw the thread gauge 11 and the female thread 60 together. The thread inspection device 1 according to this embodiment can inspect the threads of the threaded portion 62 even when the contact state has not been reached.

[0038] Next, the operation of the thread inspection device according to this embodiment will be explained with reference to Figure 7. Figure 7 is a flowchart showing the operation of the thread inspection device according to this embodiment. In step S20, if the contact detection unit 40 detects contact between the thread gauge 11 and the chamfered portion 61 of the female thread 60 (step S20: YES), the process is the same as in the first embodiment described above, so the subsequent processing will be omitted.

[0039] First, the object to be inspected W, which is fixed to the slide section 70, is moved by a moving mechanism (not shown) to move the female thread 60 of the object to be inspected W downwards to the thread inspection device 1. At this time, the thread axis of the threaded portion 62 in the female thread 60 and the thread axis of the thread gauge 11 of the inspection section 10 are coaxial.

[0040] When the object to be inspected W is set in a predetermined position, the control unit 50 operates the reciprocating movement unit 22 to lower the inspection unit 10 toward the object to be inspected W at a predetermined speed (step S10).

[0041] If the contact detection unit 40 does not detect contact between the screw gauge 11 and the chamfered portion 61 of the female thread 60 (step S20: NO), the control unit 50 compares the distance X from the tip of the screw gauge 11 to the chamfered portion 61 of the female thread 60 with the amount x of movement of the screw gauge 11 by the gauge moving unit 20 (step S100). In step S100, if it is determined that the amount of movement x ≤ distance X (step S100: NO), the process returns to step S10, and the reciprocating movement unit 22 continues to lower the inspection unit 10. In step S100, if it is determined that distance X < amount of movement x (step S100: YES), the gauge movement unit 20 rotates and moves the screw gauge 11 in the depth direction of the female screw 60 according to the lead of the female screw 60 (step S50), and the screw gauge 11 is screwed into the threaded portion 62 of the female screw 60.

[0042] Next, in the same manner as in the first embodiment described above, steps S60 to S90 are performed to complete the inspection of the female thread 60 by the thread inspection device 1.

[0043] In this way, based on the amount of movement of the screw gauge 11 by the gauge moving unit 20, the control unit 50 rotates and moves the screw gauge 11 in the depth direction of the female thread 60 in the object to be inspected W using the gauge moving unit 20. As a result, the control unit 50 can control the rotation and reciprocating movement of the gauge moving unit 20 based on the amount of movement of the screw gauge 11, and even if the screw gauge 11 does not come into contact with the chamfered portion 61 of the female thread 60, the threads of the female thread 60 in the object to be inspected W can be inspected without stopping the device. [Explanation of Symbols]

[0044] 1. Screw thread inspection device 10. Inspection Department 11 Screw gauges 12 Male threaded section 13 Gauge fixing part 20 Gauge Moving Section 21 Rotary drive unit 22 Reciprocating movement section 30 Torque detection unit 40 Contact detection unit 50 Control Unit 60 Female thread 61 Chamfered section 62 Threaded section 70 Slide section W: Items to be inspected

Claims

1. A screw gauge having at least a male threaded portion formed on its tip side, A gauge moving part supports the screw gauge so that it can rotate around the screw shaft and can reciprocate in the direction of the screw shaft, A control unit that controls the rotation and reciprocating movement of the screw gauge by the gauge moving unit, A torque detection unit capable of detecting the torque applied to the screw gauge, The screw gauge is further equipped with a contact detection unit capable of detecting when it has come into contact with the chamfered portion of the female screw on the object to be inspected. The control unit, When the contact detection unit detects that the screw gauge and the chamfered portion of the female thread are in contact, the gauge moving unit rotates the screw gauge and maintains the contact state between the screw gauge and the chamfered portion of the female thread. When the thread start position of the screw gauge coincides with the thread start position of the female thread, and the screw gauge is screwed into the female thread to a predetermined depth, the gauge moving part causes the screw gauge to rotate and move in accordance with the lead of the screw gauge. A distinctive screw thread inspection device.

2. In the thread inspection device according to claim 1, The control unit applies a static load to the chamfered portion of the female screw that allows the screw gauge to descend in the depth direction of the female screw when the thread start position of the screw gauge coincides with the thread start position of the female screw, thereby maintaining contact. A distinctive screw thread inspection device.

3. In the thread inspection device according to claim 1, The control unit rotates and moves the screw gauge in the depth direction of the female thread in the object to be inspected by the gauge moving unit, based on the amount of movement of the screw gauge by the gauge moving unit. A distinctive screw thread inspection device.

Images