Screw hole quality assurance device

Abstract

To provide a screw hole quality guarantee device with a structure that facilitates attachment and detachment of quality guaranteeing tools for inspection and re-tapping, and is adaptive to an angle of deviation of a screw hole and effective in up / down movement and centering of the quality guaranteeing tools.SOLUTION: A screw hole quality guarantee device inserts a quality guaranteeing tool 1 into a screw hole formed in an article to perform inspection, and comprises: a rotation transmission shaft 19 which is fitted to the quality guaranteeing tool 1 to rotate it; a first steel ball 14 which abuts on a peripheral edge part of the quality guaranteeing tool 1; a second steel ball 15 which is fitted to a groove part 1a provided to the quality guaranteeing tool 1 and also larger than the first steel ball 14; a retainer 13 which retains the first steel ball 14 and second steel ball 15; a steel ball presser 12 which is provided with a first taper part 12a abutting on the first steel ball 14 to increase the diameter downward and a second taper part 12b abutting on the second steel ball 15 to increase the diameter downward, and that can move up and down; and a tool connection part which comprises energizing means for energizing the steel ball presser 12 downward.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a screw hole quality assurance device for inserting a quality assurance tool into a screw hole formed in an article.

Background Art

[0002] Conventionally, a large number of screw holes are formed in industrial parts such as automotive parts, and a screw hole inspection device for inspecting the quality of the screw diameter and screw depth of the screw holes has been proposed.

[0003] For example, in Patent Document 1, an upper limit and a lower limit of an appropriate screwing torque value corresponding to an appropriate screw diameter are set in advance, an upper limit and a lower limit of an appropriate screw depth position corresponding to an appropriate screw depth are set in advance, and an appropriate torque increase value is set in advance. An invention related to a screw hole inspection device is described in which the quality of the screw diameter and screw depth is inspected by comparing these values with the detected torque value.

[0004] Further, in Patent Document 2, after moving a screw gauge by a robot arm provided with a force detection unit and bringing it into contact with a screw hole, the force applied to the screw gauge is detected by the force detection unit and the screw gauge is moved, so that the screw gauge can be easily and accurately fastened to the screw hole. An invention related to a control device is described.

[0005] Further, in Patent Document 3, an invention related to a screw hole inspection device is described in which the position of the start point of the complete thread of the screw gauge is always mounted in a positioned state so as to have a constant phase difference with respect to the screwing start position of the screw hole to be inspected. And by providing a shaft misalignment allowance part that allows misalignment of the rotating shaft part, even if the central axis of the screw gauge and the central axis of the screw hole are slightly misaligned, the screw gauge moves in the horizontal direction to absorb this misalignment.

Prior Art Documents

Patent Documents

[0006] [Patent Document 1] Japanese Patent Application Publication No. 9-280854 [Patent Document 2] Japanese Patent Publication No. 2018-202602 [Patent Document 3] Japanese Patent Publication No. 2018-77060 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] Incidentally, in screw hole inspection, screw holes can have various diameters depending on the location, even within the same part. Furthermore, the inspection tools (screw gauges) used for a single screw hole may be a combination of several types, such as those without threads (no tap), those that can be properly screwed in and inserted (GO), and those that cannot be inserted (NG). Therefore, since the inspection tools used in screw hole inspection equipment need to be replaced frequently, an easily detachable connection structure is required.

[0008] Furthermore, due to manufacturing tolerances, even parts of the same type may have screw holes that are slightly tilted relative to the design angle (angle deviation). While extreme tilts are to be expected, angle deviations within the acceptable range should be considered acceptable. However, if the screw hole is angled, the transmission of rotational force to the inspection tool will be impaired, leading to inaccuracies in torque measurements.

[0009] Furthermore, there is room for improvement in the floating mechanism for centering the inspection tool.

[0010] Furthermore, the same problem occurs not only during the inspection of screw holes, but also during the process of removing welding debris and other contaminants from the screw holes (retapping).

[0011] The present invention solves the above-mentioned conventional problems and provides a screw hole quality assurance device that allows for easy attachment and detachment of quality assurance tools for inspection and retapping, can accommodate screw hole deviations, and has a structure that is effective for vertical movement and centering of quality assurance tools. [Means for solving the problem]

[0012] To solve the above problems, the screw hole quality assurance device of the present invention is a screw hole quality assurance device for inserting a quality assurance tool into a screw hole formed in an article, and is characterized by having a tool connection part comprising: a rotation transmission shaft that fits into and rotates the quality assurance tool; a first steel ball that abuts against the peripheral edge of the quality assurance tool; a second steel ball larger than the first steel ball that fits into a groove provided in the quality assurance tool; a holder that holds the first steel ball and the second steel ball; a vertically movable steel ball retainer provided with a first tapered portion that abuts against the first steel ball and expands in diameter downward and a second tapered portion that abuts against the second steel ball and expands in diameter downward; and a biasing means that biases the steel ball retainer downward.

[0013] Preferably, the floating section comprises a fixed table, a movable frame that moves due to external stress, a fixed magnet provided on the fixed table, a movable magnet provided on the movable frame, and a magnet moving cylinder for moving the movable magnet.

[0014] Furthermore, the quality assurance described above includes screw hole inspection, which involves determining the quality of screw hole diameter, screw depth, etc., and work to remove welding debris and other contaminants from screw holes (retapping). [Effects of the Invention]

[0015] The screw hole quality assurance device of the present invention is a screw hole quality assurance device that inserts a quality assurance tool into a screw hole formed in an article. The device has a tool connection part comprising a rotation transmission shaft that fits into and rotates the quality assurance tool, a first steel ball that abuts against the peripheral edge of the quality assurance tool, a second steel ball larger than the first steel ball that fits into a groove provided in the quality assurance tool, a holder that holds the first and second steel balls, a vertically movable steel ball retainer having a first tapered portion that abuts against the first steel ball and expands in diameter downward and a second tapered portion that abuts against the second steel ball and expands in diameter downward, and a biasing means that biases the steel ball retainer downward.

[0016] As the steel ball retainer moves up and down, the contact position between the first tapered portion and the first steel ball changes, and the contact position between the second tapered portion and the second steel ball also changes, causing the first and second steel balls to move horizontally (inward and outward) perpendicular to the axis of rotation. When the second steel ball moves inward, the groove provided in the quality assurance tool engages with the second steel ball, resulting in a connected state (mounted state). When the second steel ball moves outward, the groove provided in the quality assurance tool disengages from the second steel ball, resulting in a disconnected state (removed state). Since the steel ball retainer is biased downward, the mounted state is maintained after the quality assurance tool is mounted.

[0017] Furthermore, when an external horizontal stress is applied to the quality assurance tool while the screw hole is misaligned, a force acts to push the first and second steel balls outward from the quality assurance tool, and a corresponding force acts to push the steel ball retainer upward. This allows the quality assurance tool to continue rotating while absorbing the external stress on it caused by the misalignment of the screw hole. Since the steel ball retainer is biased downward, the quality assurance tool returns to a vertical position when the external stress is removed.

[0018] Furthermore, if the system includes a floating section comprising a fixed table, a movable frame that moves due to external stress, a fixed magnet on the fixed table, a movable magnet on the movable frame, and a magnet-moving cylinder for moving the movable magnet, the quality assurance tool can be centered even with a wide stroke without increasing the repulsive force.

[0019] Thus, the screw hole quality assurance device of the present invention allows for easy attachment and detachment of quality assurance tools for inspection and retapping, can accommodate screw hole deviations, and has a structure that is effective for vertical movement and centering of quality assurance tools. [Brief explanation of the drawing]

[0020] [Figure 1] This is a front view showing a screw hole quality assurance device according to an embodiment of the present invention. [Figure 2] Cross-sectional view (A) and longitudinal sectional view (B) showing the tool connection part in the state where the quality assurance tool is mounted. [Figure 3] Cross-sectional view (A) and longitudinal sectional view (B) showing the tool connection part in the state where the quality assurance tool is removed. [Figure 4] Cross-sectional view (A), longitudinal sectional view (normal) (B), and longitudinal sectional view (deflection angle) (C) showing the tool connection part during operation. [Figure 5] Front view (A) and cross-sectional view of the tip (B) showing the rotation transmission shaft. [Figure 6] Plan view (A), longitudinal sectional view (ascending) (B), and longitudinal sectional view (descending) (C) showing the hollow cylinder part. [Figure 7] Plan view showing the floating part (X direction). [Figure 8] Plan view showing the floating part (Y direction). [Figure 9] Side view showing the floating part.

Mode for Carrying Out the Invention

[0021] Next, referring to FIGS. 1 to 9, a screw hole quality assurance device according to an embodiment of the present invention will be described. The screw hole quality assurance device 100 according to the present embodiment inserts a quality assurance tool into a screw hole formed in an industrial part (article) such as an automotive part. Note that quality assurance includes screw hole inspection for determining the quality of the screw diameter, screw depth, etc. of the screw hole and operations (retapping) for removing welding dust, etc. attached to the screw hole.

[0022] Figure 1 is a front view showing the screw hole quality assurance device 100. The screw hole quality assurance device 100 is attached to the robot arm (not shown) of an industrial robot via a robot mounting section 5. The industrial robot holds information about the screw holes formed in the article (screw diameter, screw depth, position, etc.), selects the screw hole to be inserted into and the quality assurance tool to be used, and automatically performs tasks such as attaching and detaching the quality assurance tool, inserting it into the screw hole, determining whether it is good or bad, and retapping, while controlling the robot arm. The determination of whether it is good or bad can be performed based on known methods (criteria).

[0023] The screw hole quality assurance device 100 includes a quality assurance tool 1 with a measuring gauge 2 (or retapping section) attached to its tip, a tool connection section 10 for connecting the quality assurance tool 1, a hollow cylinder section 20 for moving the quality assurance tool 1 up and down, a rotary motor 3 for rotating the quality assurance tool 1, a depth measuring section 4 for measuring the screw depth of the screw hole, and a floating section 30 that corresponds to the horizontal movement of the screw hole quality assurance device 100. The tool connection section 10, the hollow cylinder section 20, and the floating section 30 will be described in detail below.

[0024] Figure 2 shows (A) a cross-sectional view and (B) a longitudinal cross-sectional view of the tool connection part 10 with the quality assurance tool attached. Figure 3 shows (A) a cross-sectional view and (B) a longitudinal cross-sectional view of the tool connection part 10 with the quality assurance tool removed.

[0025] The tool connection section 10 includes an outer ring 11, a steel ball retainer 12, a cage 13, a first steel ball 14, a second steel ball 15, a radial bearing 16, thrust bearings 17, 18, a rotation transmission shaft 19, and a biasing means (not shown).

[0026] The outer ring 11 moves up and down by a vertical drive cylinder attached to the device, and the radial bearing 16, thrust bearings 17, 18 and steel ball retainer 12 are held by the outer ring 11. The radial bearing 16, thrust bearings 17, 18 and steel ball retainer 12 move up and down in accordance with the vertical movement of the outer ring 11.

[0027] The steel ball retainer 12 is a cylindrical body having a first tapered portion 12a and a second tapered portion 12b on its inner wall surface. The first tapered portion 12a is located above the second tapered portion 12b, widens in diameter downwards, and contacts the first steel ball 14. The second tapered portion 12b is located below the first tapered portion 12a, widens in diameter downwards, and contacts the second steel ball 15. The inner wall surface of the steel ball retainer 12 gradually widens in diameter in the following order: upper flat portion, first tapered portion 12a, middle flat portion, second tapered portion 12b, and lower flat portion.

[0028] The first steel ball 14 and the second steel ball 15 are held by a cylindrical retainer 13 having an opening sized to match each steel ball. The retainer 13 is not held by the outer ring 11 and does not move up and down in accordance with the vertical movement of the outer ring 11. The second steel ball 15 is larger than the first steel ball 14. In this embodiment, the number of first steel balls 14 and second steel balls 15 is set to six each, but this is not limited to this, and there may be fewer or more as long as the quality assurance tool can be attached.

[0029] The first steel ball 14 abuts against the upper peripheral edge of the quality assurance tool 1 when the quality assurance tool 1 is mounted as shown in Figure 2. The second steel ball 15 is fitted into a groove 1a provided on the peripheral edge of the quality assurance tool 1 when the quality assurance tool 1 is mounted as shown in Figure 2.

[0030] The biasing means (not shown) of the tool connection part 10 biases the outer ring 11 downward, so that the steel ball retainer 12 held by the outer ring 11 is always biased downward.

[0031] In the mounted state of the quality assurance tool 1 shown in Figure 2, the outer ring 11 (steel ball retainer 12) moves downward, and the second steel ball 15 is pushed inward by the second tapered portion 12b. The second steel ball 15 then fits into the groove 1a of the quality assurance tool 1, and the quality assurance tool 1 can be maintained in the mounted state.

[0032] At this time, the rotational transmission shaft 19 is inserted into the fitting hole 1b provided on the upper surface of the quality assurance tool 1. Then, as the rotational transmission shaft 19 rotates, the quality assurance tool 1 rotates.

[0033] On the other hand, in the removal state of the quality assurance tool 1 shown in Figure 3, the outer ring 11 (steel ball retainer 12) moves upward, and the distance by which the second tapered portion 12b pushes the second steel ball 15 inward decreases, so the second steel ball 15 moves outward compared to the installed state. Then the second steel ball 15 comes out of the groove 1a of the quality assurance tool 1, and the quality assurance tool 1 can be removed.

[0034] Figure 4 shows (A) a cross-sectional view, (B) a longitudinal section (normal), and (C) a longitudinal section (angled) of the tool connection during operation. As shown in Figures 4(A) and (B), when the screw holes are formed as designed (normal), the quality assurance tool 1 rotates in accordance with the rotation of the rotation transmission shaft 19 while mounted perpendicularly to the tool connection 10, and the steel ball retainer 12, the first steel ball 14, and the second steel ball 15 also rotate in the direction shown.

[0035] On the other hand, as shown in Figure 4(C), if the screw hole is not formed as designed and is tilted (angle deviation), an external stress acts laterally as the quality assurance tool 1 is inserted into the screw hole. This causes a force to act outward on the first steel ball 14 and the second steel ball 15, but this force can be absorbed by the rising steel ball retainer 12. When the quality assurance tool 1 returns to a vertical position and the external stress is eliminated, the steel ball retainer 12, which is always biased downward, moves downward to its normal position. The steel ball retainer angle (taper angle) of the steel ball retainer 12 is set so that the first steel ball 14 and the second steel ball 15 move outward when there is an external stress.

[0036] Figure 5 shows (A) a front view and (B) a cross-sectional view of the tip of the rotation transmission shaft 19. The tip 19a of the rotation transmission shaft 19 is approximately spherical in side view but hexagonal in cross-section. The hexagonal cross-section ensures reliable transmission of rotational force to the quality assurance tool 1, while the approximately spherical side view allows for the transmission of rotational force and maintenance of rotation even if the quality assurance tool 1 is tilted. The fitting hole 1b of the quality assurance tool 1 is also hexagonal.

[0037] Figure 6 shows (A) a plan view, (B) a vertical cross-sectional view (upward), and (C) a vertical cross-sectional view (downward) of the hollow cylinder section 20. The hollow cylinder section 20 comprises a cylinder tube 21, a piston 22, and a spring 23. The cylinder tube 21 is a cylindrical body having a hollow section 6 that penetrates in the direction of the center axis. The piston 22 is a cylindrical body that moves up and down inside the wall surface of the cylindrical cylinder tube 21. The cylinder tube 21 and the piston 22 are connected by a spring 23 that biases the piston 22 upward, so that the piston 22 moves downward due to pressure such as air, and returns upward when the pressure is released. In this way, by combining the cylindrical cylinder tube 21 and the cylindrical piston 22, a hollow section 6 is obtained, and the hollow section 6 can be effectively utilized as a passage for the rotating shaft of the screw hole quality assurance device 100. Note that the biasing means is not limited to a spring.

[0038] The floating section 30 will be described with reference to Figures 7 to 9. The floating section 30 consists of a floating section 40 in the X direction and a floating section 50 in the Y direction. Figure 7 is a plan view showing the floating section 40 (X direction), Figure 8 is a plan view showing the floating section 50 (Y direction), and Figure 9 is a side view showing the floating section 30. In Figures 7 and 8, the left-right direction is the X direction and the up-down direction is the Y direction.

[0039] The floating section 40 includes a fixed table 41, a movable frame 42 that can move in accordance with the movement of the quality assurance tool 1 in the X direction, fixed magnets 47, 47, 47, 48, 48, 48 provided on the fixed table 41, movable magnets 45, 45, 45, 46, 46, 46 provided on the movable frame 42, magnet moving cylinders 43a, 43b for moving the movable magnets 45, 45, 45, and magnet moving cylinders 44a, 44b for moving the movable magnets 46, 46, 46. The three movable magnets 45 are held in a magnet holder 43c, and the magnet moving cylinders 43a, 43b are connected to the magnet holder 43c. Similarly, the three movable magnets 46 are held in a magnet holder 44c, and the magnet moving cylinders 44a, 44b are connected to the magnet holder 44c.

[0040] The movable magnet 45 and the fixed magnet 47 repel each other. Similarly, the movable magnet 46 and the fixed magnet 48 repel each other. By extending and retracting the magnet movement cylinders 43a, 43b and 44a, 44b, the repulsive force between the movable magnets and the fixed magnets can be adjusted. For example, in the state shown in Figure 7, the repulsive force between the movable magnet 46 and the fixed magnet 48 is greater than the repulsive force between the movable magnet 45 and the fixed magnet 47. When the movable frame 42 moves, the repulsive forces between the left and right magnets can be controlled to become closer by changing the positions of the movable magnets 45 and 46.

[0041] The floating section 50 is formed by rotating the floating section 40 by 90 degrees to accommodate movement in the Y direction. The configuration of each section is the same as that of the floating section 40, so a detailed explanation is omitted. As shown in Figure 9, the floating section 30 is constructed by stacking the floating section 40 in the X direction and the floating section 50 in the Y direction, allowing it to accommodate movement on the XY plane.

[0042] In the event of external stress caused by the misalignment of the screw hole, the floating section 30 can also provide support in addition to the tool connection section 10 described above. In the case of a typical floating mechanism, the repulsive force (or attractive force) increases according to the amount of displacement, so the amount of floating slide is very small and the range of use is limited. In contrast, the floating section 30 according to this embodiment can increase the stroke amount by changing the position of the movable magnets 45, 46, 55, 56 when the movable frames 42, 52 move, thereby controlling and stabilizing the repulsive forces in the front, back, left, and right directions to be closer together.

[0043] In Figure 7, springs 49 are installed between the magnet moving cylinders 43a and 43b and the magnet holding part 43c, and between the magnet moving cylinders 44a and 44b and the magnet holding part 44c. The springs 49 are for use when the screw hole quality assurance device 100 is tilted horizontally (when the quality assurance tool is inserted horizontally). When the screw hole quality assurance device 100 is tilted horizontally, gravity acts on the floating part 40. The springs 49 are designed to bias in a direction that counteracts the effect of gravity at this time. The floating part 50 shown in Figure 8 is similar.

[0044] The screw hole quality assurance device 100 according to this embodiment is a screw hole quality assurance device that inserts a quality assurance tool 1 into a screw hole formed in an article. It has a rotation transmission shaft 19 that fits into and rotates the quality assurance tool 1, a first steel ball 14 that abuts against the peripheral edge of the quality assurance tool 1, a second steel ball 15 that is larger than the first steel ball 14 and fits into a groove 1a provided on the quality assurance tool 1, a holder 13 that holds the first steel ball 14 and the second steel ball 15, a vertically movable steel ball retainer 12 provided with a first tapered portion 12a that abuts against the first steel ball 14 and expands in diameter downward and a second tapered portion 12b that abuts against the second steel ball 15 and expands in diameter downward, and a biasing means that biases the steel ball retainer 12 downward.

[0045] As the steel ball retainer 12 moves up and down, the contact position between the first tapered portion 12a and the first steel ball 14 changes, and the contact position between the second tapered portion 12b and the second steel ball 15 also changes, causing the first steel ball 14 and the second steel ball 15 to move horizontally (inward and outward) perpendicular to the axis of rotation. When the second steel ball 15 moves inward, the groove 1a provided in the quality assurance tool 1 engages with the second steel ball 15, resulting in a connected state (mounted state). When the second steel ball 15 moves outward, the engagement between the groove 1a provided in the quality assurance tool 1 and the second steel ball 15 disengages, resulting in a disconnected state (removed state). Since the steel ball retainer 12 is biased downward, the mounted state is maintained after the quality assurance tool 1 is mounted.

[0046] Furthermore, when an external horizontal stress is applied to the quality assurance tool 1 while the screw hole is misaligned, a force acts on the quality assurance tool 1 that pushes the first steel ball 14 and the second steel ball 15 outward, and in conjunction with this, a force acts to push the steel ball retainer 12 upward. This allows the quality assurance tool 1 to continue rotating while absorbing the external stress on the quality assurance tool 1 caused by the misalignment of the screw hole. Since the steel ball retainer 12 is biased downward, the quality assurance tool 1 returns to a vertical position when the external stress is removed.

[0047] Furthermore, since it has a floating section 30 comprising a fixed table 31, a movable frame 32 that moves due to external stress, a fixed magnet 33 provided on the fixed table 31, a movable magnet 34 provided on the movable frame 32, and a magnet moving cylinder 35 that moves the movable magnet 34, the quality assurance tool 1 can be centered even with a wide stroke without increasing the repulsive force.

[0048] Thus, the screw hole quality assurance device 100 according to this embodiment allows for easy attachment and detachment of the quality assurance tool 1 for inspection and retapping, can accommodate screw hole deviations, and has a structure that is effective for vertical movement and centering of the quality assurance tool 1.

[0049] Although a screw hole quality assurance device according to an embodiment of the present invention has been described above, the present invention is not limited to the embodiments described above, and various other modifications are possible.

[0050] For example, in the above embodiment, the screw hole quality assurance device 100 is attached to the robot arm of an industrial robot, but the mounting location is not particularly limited and can be any conveying equipment, fixed equipment, wall surface, etc.

[0051] Furthermore, in the above embodiment, the floating section 30 is configured as a floating section 40 in the X direction and a floating section 50 in the Y direction, but the X and Y directions may be configured as a single unit. Alternatively, a ring-shaped movable frame may be provided around a circular fixed table so that the magnets face each other. [Explanation of symbols]

[0052] 1. Quality Assurance Tools 2 Measuring gauges 3-speed motor 4 Depth measuring section 5. Robot mounting section 6 Hollow part 10 Tool connection section 11 Outer ring 12 Steel ball retainer 13 Cage 14. The first steel ball 15. The second steel ball 16 Radial bearings 17 Thrust Tactics 18 Thrust bearings 19 Rotational transmission shaft 20 Hollow cylinder section 21 Cylinder tube 22 pistons 23 Spring 30 Floating section 40 Floating section (X direction) 41 Fixed Table 42 Movable Frames 43a Cylinder for moving magnets 43b Cylinder for moving magnets 43c Magnet holding part 44a Cylinder for moving magnets 44a Cylinder for moving magnets 44b Cylinder for moving magnets 44c Magnet holding part 45 Movable Magnets 46 Movable Magnets 47 Fixed magnets 48 Fixed Magnets 49 Spring 50 Floating section (Y direction) 51 Fixed Table 52 Movable Frames 53a Cylinder for moving magnets 53b Cylinder for moving magnets 53c Magnet holding part 54a Cylinder for moving magnets 54a Cylinder for moving magnets 54b Cylinder for moving magnets 54c Magnet holding part 55 Movable Magnets 56 Movable Magnets 57 Fixed Magnet 58 Fixed Magnet 59 Spring 100 Screw Hole Quality Assurance Device

Claims

1. A screw hole quality assurance device for inserting a quality assurance tool into a screw hole formed in an article, A screw hole quality assurance device characterized by having a tool connection portion comprising: a rotation transmission shaft that is fitted into and rotated by the quality assurance tool; a first steel ball that abuts against the peripheral edge of the quality assurance tool; a second steel ball larger than the first steel ball that fits into a groove provided in the quality assurance tool; a holder that holds the first steel ball and the second steel ball; a vertically movable steel ball retainer having a first tapered portion that abuts against the first steel ball and expands in diameter downward, and a second tapered portion that abuts against the second steel ball below the first tapered portion and expands in diameter downward; and a biasing means for biasing the steel ball retainer downward.

2. The screw hole quality assurance device according to claim 1, characterized in that it has a floating section comprising a fixed table, a movable frame that moves due to external stress, a fixed magnet provided on the fixed table, a movable magnet provided on the movable frame, and a magnet moving cylinder for moving the movable magnet.

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