Thread Gauge

Abstract

To provide a screw gauge capable of realizing a superior core alignment mechanism with a simple structure.SOLUTION: A screw gauge includes: a gauge part 2 having an externally-threaded complete screw 20 on an outer peripheral surface from one end and a bottomed hole 21 on the other end surface; a shaft 1 with a tip part thereof inserted in the bottomed hole 21 of the gauge part 2; and a cylindrical sleeve 3 to be attached to an opening part of the bottomed hole 21. The shaft 1 includes: a ball point part 11 having an external thread shape capable of torque transmission at a tip part thereof; and a shaft part 12 having a maximum outside diameter smaller than a maximum outside diameter of the ball point part. At least on an inner peripheral surface in a vicinity of the bottomed hole 21, an engagement part 21a is formed, in an internal thread shape capable of torque transmission corresponding to the ball point part 11. The sleeve 3 has an inner diameter smaller than the maximum outside diameter of the ball point part 11 and larger than the maximum outside diameter of the shaft part 12 when attached to the opening part of the bottomed hole 21.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present disclosure relates to a thread gauge for inspecting female threaded holes. [Background technology]

[0002] Thread gauges are used to inspect the formed female threaded holes. Thread gauges for inspecting female threaded holes have a male threaded gauge part at the tip of their shaft, and inspect the female threaded hole by checking whether the gauge part can be properly screwed into the formed female threaded hole. There are various types of thread gauges, such as standard thread gauges with an accurate gauge part that serves as a reference, and limit thread gauges that are made up of a pair of gauges, a go side gauge with a gauge part made smaller than the reference dimension, and a stop side gauge with a gauge part made larger than the reference dimension.

[0003] Inspection using thread gauges may be performed completely manually by an operator, semi-automatically by automating the rotation of the gauge using an electric screwdriver, or fully automatically by automating the positioning of the gauge part to the female screw hole. However, positioning the gauge part to the female screw hole is difficult, and this is an obstacle to shortening the inspection time when inspecting all female screw holes. In manual or semi-automatic inspections as well as fully automatic inspections, improvements are desired in the alignment of the gauge part and the female screw hole. Furthermore, if the alignment is performed smoothly, wear on the gauge can be reduced. Patent Document 1 below discloses a thread gauge in which the gauge part provided at the tip of the shaft has an alignment mechanism. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] German Utility Model No. 202004018244 Summary of the Invention [Problem to be solved by the invention]

[0005] In the thread gauge disclosed in Patent Document 1, a hole is formed in the gauge section along the axial direction, and the tip of the shaft is inserted into the hole. The tip of the shaft and the gauge section are connected by a pin at the center of the axial direction of the gauge section. As a result, the gauge section can swing relative to the shaft with the pin as an axis. Furthermore, by making the inner diameter of both ends of the pin insertion hole formed at the tip of the shaft larger than that of the center, the pin itself can swing to a certain extent relative to the shaft, and the swing freedom of the gauge section relative to the shaft is also expanded. By making the gauge section swingable relative to the shaft in this way, a centering function is realized. Patent Document 1 also discloses a thread gauge in which a centering function is realized by disposing a steel material having a certain degree of flexibility between the gauge section and the shaft.

[0006] However, there is a demand for a thread gauge with a simpler structure and better centering function, and an object of the present disclosure is to provide a thread gauge that realizes an excellent centering mechanism with a simple structure. [Means for solving the problem]

[0007] The thread gauge according to the present disclosure is a thread gauge for inspecting a female threaded hole, and includes a gauge section having a male screw-like complete thread formed on an outer peripheral surface from one end and a bottomed hole formed on the other end surface, a shaft having a tip inserted into the bottomed hole of the gauge section, and a cylindrical sleeve attached to an opening of the bottomed hole. The shaft has a ball point section having a male shape capable of transmitting torque at the tip, and a shaft section extending from the ball point section and having a maximum outer diameter smaller than the maximum outer diameter of the ball point section. An engagement section having a female shape capable of transmitting torque corresponding to the ball point section is formed on the inner peripheral surface at least near the bottom of the bottomed hole. When attached to the opening, the sleeve has an inner diameter smaller than the maximum outer diameter of the ball point section and larger than the maximum outer diameter of the shaft section.

[0008] The sleeve may be formed with a slit extending from one end to the other end in the axial direction.

[0009] Furthermore, a male threaded portion may be formed on the outer peripheral surface of the sleeve, and a female threaded portion that screws into the male threaded portion may be formed on the inner peripheral surface of the bottomed hole.

[0010] Alternatively, a protrusion may be provided on the outer circumferential surface of the sleeve so as to extend in the circumferential direction, and a groove for accommodating the protrusion may be formed in the circumferential direction on the inner circumferential surface of the bottomed hole.

[0011] The sleeve may be formed with a flange that abuts against the other end face of the gauge portion, and the maximum outer diameter of the flange may be larger than the maximum outer diameter of the gauge portion.

[0012] Furthermore, when the maximum outer diameter of the gauge portion is D, the height H from one end face of the gauge portion to the center of the bottom surface of the bottomed hole may be within the range of 0.2D≦H≦D / [2(3^(1 / 2)]. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is an overall side view of a thread gauge according to a first embodiment. [Diagram 2] FIG. 2 is an exploded side view (partially in cross section) of the tip portion of the thread gauge. [Diagram 3] 4A to 4C are three-view diagrams of a sleeve in the above-mentioned thread gauge. [Figure 4] FIG. 4 is a cross-sectional view of a tip portion of the thread gauge. [Diagram 5] FIG. 4 is a cross-sectional view of the tip portion of the thread gauge (in a state where the tip portion is screwed into a female thread). [Figure 6] FIG. 4 is a cross-sectional view of the tip portion of the thread gauge (contact state with the female thread opening). [Figure 7] FIG. 4 is a side view (partially in cross section) of the thread gauge in a bent shaft portion. [Figure 8] FIG. 6 is a view corresponding to FIG. 5 of a thread gauge according to a second embodiment. [Figure 9] FIG. 4 is a view corresponding to FIG. 2 of a thread gauge according to a third embodiment. [Figure 10] 13A to 13C are three-view diagrams of a sleeve of a thread gauge according to a third embodiment. [Figure 11] FIG. 13 is a three-view diagram of a sleeve of a thread gauge according to a fourth embodiment. [Figure 12] FIG. 13 is a three-view diagram of a sleeve of a thread gauge according to a fifth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, an embodiment of the thread gauge will be described with reference to the drawings.

[0015] The thread gauge of the embodiment is a thread gauge for inspecting formed female thread holes, and is formed in the form of a bit so as to be attached to the chuck part of an electric screwdriver. As shown in Fig. 1, the thread gauge of the embodiment is composed of three members: a shaft 1, a gauge part 2, and a sleeve 3. In the first embodiment, the shaft 1, the gauge part 2, and the sleeve 3 are all made of metal.

[0016] A chuck portion 10 is formed at the base end of the shaft 1. The chuck portion 10 has a hexagonal cross section like a driver bit, and a groove for chucking is formed in the circumferential direction. On the other hand, as shown in FIG. 2, the tip end of the shaft 1 has a ball point portion 11 having a male shape capable of transmitting torque. The "male shape capable of transmitting torque" is a shape having at least one convex portion protruding in a radial direction perpendicular to the rotation axis of the shaft 1. When a plurality of convex portions are provided, it is preferable that they are provided evenly in the circumferential direction. For example, the "male shape capable of transmitting torque" in this embodiment is a convex shape having a regular hexagonal cross section used in ordinary hexagonal wrenches. Therefore, the ball point portion 11 has a shape similar to the tip end of an ordinary ball point hexagonal wrench, and can be inserted into the female hexagonal hole of the other side even if the shaft 1 is tilted to some extent, and the shaft 1 can be rotated even if the shaft 1 is tilted.

[0017] The chuck portion 10 and the ball point portion 11 are integrally connected by the shaft portion 12. That is, the shaft portion 12 extends from the ball point portion 11 and is connected to the chuck portion 10. The shaft portion 12 in this embodiment is a simple round bar. The outer diameter of the shaft portion 12 is constant and is smaller than at least the maximum outer diameter of the ball point portion 11. The cross section of the shaft portion 12 may be, for example, a regular polygon, and may not be of uniform size in the length direction. In that case, the maximum outer diameter of the shaft portion 12 is smaller than at least the maximum outer diameter of the ball point portion 11. Although the shaft 1 is made of metal, it is formed thin as described above, and therefore it is capable of bending, in other words, it is capable of being flexible.

[0018] When shaft portion 12 is made of metal, its length is set to at least 5 times the maximum outer diameter of gauge portion 2 in order to achieve the above-mentioned deflection. If shaft portion 12 is too long, twisting occurs, making it difficult to use as a thread gauge, so when shaft portion 12 is made of metal, the length is set to 10 times the maximum outer diameter of gauge portion 2 or less. Furthermore, if shaft portion 12 is too thin, twisting occurs, making it difficult to use as a thread gauge, so it is set to at least 1 / 4 of the maximum outer diameter of gauge portion 2 or more.

[0019] The gauge section 2 has a male complete thread 20 formed on its outer circumferential surface from one end. In this embodiment, as shown in FIG. 2, the complete thread 20 is formed on the entire circumferential surface from one end to the other end of the gauge section 2. A bottomed hole 21 is drilled axially in the direction of the rotation axis of the gauge section 2 on the other end surface of the gauge section 2. The bottomed hole 21 has a depth that reaches the tip of the gauge section 2, i.e., the vicinity of the one end surface. An engagement section 21a having a female shape capable of transmitting torque corresponding to the ball point section 11 is formed on the inner circumferential surface near the bottom of the bottomed hole 21. The engagement section 21a engages with the above-mentioned ball point section 11 to transmit torque from the shaft 1 to the gauge section 2.

[0020] The "torque-transmittable female shape" in this embodiment has at least one recess formed in a radial direction perpendicular to the rotation axis of the gauge portion 2. The number of recesses is the same as the number of protrusions in the "torque-transmittable male shape" of the ball point portion 11, and when multiple recesses are provided, they are preferably provided evenly in the circumferential direction. For example, the "torque-transmittable female shape" in this embodiment is a recess having a regular hexagonal cross section corresponding to the male shape of the ball point portion 11 described above. The circumscribing circle of the regular hexagon of the engagement portion 21a is formed slightly larger than the circumscribing circle of the ball point portion 11, but torque can be transmitted.

[0021] A cylindrical surface 21b is formed between the engaging portion 21a and the opening of the bottomed hole 21. A female thread portion 22A for mounting the sleeve 3 is formed on the cylindrical surface 21b. The circular cross section of the cylindrical surface 21b between the engaging portion 21a and the female thread portion 22A is a circumscribing circle of the regular hexagon of the engaging portion 21a. The circular cross section between the female thread portion 22A and the opening has an inner diameter slightly larger than the maximum outer diameter of a male thread portion 32A of the sleeve 3, which will be described later.

[0022] As shown in FIG. 3, the sleeve 3 is basically a cylindrical member having a through hole formed in its axial direction. However, the sleeve 3 has a slit 30, a flange 31, and a male threaded portion 32A, which will be described below. The outer diameter of the sleeve 3 is equal to or slightly smaller than the inner diameter of the cylindrical surface 21b of the bottomed hole 21 described above. The length of the sleeve 3 is equal to or slightly smaller than the axial length of the cylindrical surface 21b of the bottomed hole 21 plus the thickness of the flange 31, which will be described later. The sleeve 3 is formed with a slit 30 from one end to the other end in the axial direction. The slit 30 connects the inside and outside of the sleeve 3. The shaft portion 12 of the shaft 1 is inserted into the inside of the sleeve 3 through the slit 30. Therefore, the width of the slit 30 is equal to or slightly larger than the outer diameter of the shaft portion 12.

[0023] A flange 31 that abuts against the other end surface of the gauge portion 2 extends radially outward from one end of the sleeve 3. As shown in FIG. 3, the flange 31 has a pair of parallel flat surfaces 33 formed thereon to be used when fastening the sleeve 3 to a bottomed hole 21 described later. The flat surfaces 33 are parallel to the axial direction of the sleeve 3. As shown in FIG. 5, in this embodiment, the maximum outer diameter of the flange 31 is smaller than the maximum outer diameter of the gauge portion 2 and smaller than the minimum inner diameter of the female threaded hole 40 inspected by the thread gauge. The female threaded hole 40 shown in FIG. 5 is formed in the workpiece W. The sleeve 3 shown in FIG. 5 is shown in a cross section that does not pass through the flat surfaces 33.

[0024] A male thread portion 32A that engages with the female thread portion 22A of the gauge portion 2 described above is formed on the outer circumferential surface of the sleeve 3. However, the male thread portion 32A is not formed in the portion where the slit 30 is formed. The maximum outer diameter of the male thread portion 32A is equal to or slightly smaller than the inner diameter of the groove 22. To attach the sleeve 3 to the opening of the bottomed hole 21, the male thread portion 32A is screwed into the female thread portion 22A, and as a result, the sleeve 3 is prevented from slipping out of the gauge portion 2.

[0025] The cross-sectional view of FIG. 4 shows the maximum outer diameter of the ball point portion 11. That is, FIG. 4 shows a cross-section passing through the vertices of the regular hexagonal cross-section of the ball point portion 11 and the vertices of the regular hexagonal cross-section of the engagement portion 21a. The inner diameter of the sleeve 3 attached to the bottomed hole 21 is smaller than the maximum outer diameter of the ball point portion 11. This prevents the sleeve 3 from slipping out of the gauge portion 2. As shown in FIG. 4, the bottom surface of the bottomed hole 21 of the gauge portion 2 is formed as a curved surface whose center is convex toward the tip of the gauge portion 2, i.e., the one end surface. The radius of curvature of this bottom surface is larger than the radius of curvature of the tip of the ball point portion 11, and this bottom surface and the tip of the ball point portion 11 are in point contact.

[0026] The bottom center O of the bottomed hole 21 is located within at least 1 / 2 of the overall length of the fully threaded portion 20 toward one end of the gauge section 2, i.e., toward the tip end, and preferably within 1 / 3 of the overall length. In other words, by setting the position of the bottom of the bottomed hole 21, i.e., the bottom center O, as close to one end of the gauge section 2 as possible, the oscillation center of the gauge section 2 can be set closer to that end. By setting the oscillation center of the gauge section 2 closer to that end, the centering function of the gauge section 2 can be improved.

[0027] More preferably, when the maximum outer diameter of the gauge section 2 is D, the height H from one end face, i.e., the tip face, of the gauge section 2 to the center O of the bottom face is set within the range shown by the following inequality (1). In other words, the height H is the center thickness of the bottom wall of the bottomed hole 21. 0.2D≦H≦D / [2(3^(1 / 2)] … (1) Here, as shown in FIG. 4, D / [2(3^(1 / 2)] is the height from one end face of the intersection point of a line drawn at an angle of 30° from the circumscribing circle of one end face of the gauge section 2 toward the central axis of the gauge section 2 and the line. On the other hand, 0.2D is 20% of the maximum outer diameter of the gauge section 2. By setting the height H of the bottom center O within the range shown by inequality (1), the alignment function of the gauge section 2 can be further improved. Next, this alignment function will be explained.

[0028] The thread gauge of this embodiment has the above-mentioned configuration, and the ball point portion 11 at the tip of the shaft 1 is loosely fitted into the bottomed hole 21 of the gauge portion 2. Therefore, the gauge portion 2 can swing relative to the shaft 1, and a centering function for the female screw hole 40 into which it is screwed is realized. Furthermore, since the above-mentioned height H is set within the range shown by the above inequality (1), the swing center of the gauge portion 2 is located on the tip side of the gauge portion 2. In other words, when the gauge portion 2 is screwed into the opening of the female screw hole 40, the gauge portion 2 swings around a position close to the opening, and therefore the orientation of the gauge portion 2 tends to coincide with the axial direction of the female screw hole 40.

[0029] FIG. 6 shows the state when the gauge part 2 is screwed into the opening of the female screw hole 40. When the gauge part 2 is screwed into the opening of the female screw hole 40, if the axis of the gauge part 2 and the axis of the female screw hole 40 do not coincide, a part of the tip periphery of the gauge part 2 comes into contact with the opening edge of the female screw hole 40, and the tip periphery on the opposite side does not come into sufficient contact. In the state shown in FIG. 6, the complete thread 20 of the gauge part 2 cannot be screwed normally into the thread of the female screw hole 40. However, due to partial contact between the tip periphery of the gauge part 2 and the opening edge of the female screw hole 40, and contact between the bottom surface of the bottomed hole 21 and the tip of the ball point part 11, the gauge part 2 is swung, and the axis of the gauge part 2 and the axis of the female screw hole 40 coincide. In other words, the thread gauge and the female screw hole 40 are aligned.

[0030] At this time, as shown in FIG. 6, a triangular relationship is formed on the cross section as indicated by three arrows, so that the gauge section 2 is swung quickly and aligned. Here, in order for the alignment function to function quickly, the height H of the bottom center O, which is the apex of the triangle, is at least 2 / 1, preferably 1 / 3, of the length of the complete thread 20. More preferably, the height H is set within the range of the above inequality (1). If the height H of the bottom center O exceeds D / [2(3^(1 / 2)], the force acting due to the contact between the bottom surface of the bottomed hole 21 and the tip of the ball point section 11 tends to act in the opposite direction to the alignment of the gauge section 2, and the gauge section 2 tends to fall in the opposite direction to the alignment. Therefore, it is more preferable that the height H is D / [2(3^(1 / 2)] or less. Note that if the height H of the bottom center O is less than 0.2D, the strength of the bottom of the bottomed hole 21 may not be ensured.

[0031] In the thread gauge of Patent Document 1 mentioned above, the pin connection position of the gauge section is in the center of the height direction of the gauge section, and a force that tilts the gauge section in the opposite direction is likely to occur. In contrast, in the thread gauge of this embodiment, the ball point section 11 is positioned sufficiently far toward the tip side of the gauge section 2, so an excellent centering function is realized. In addition, in the thread gauge of Patent Document 1, a hole needs to be formed in the thread section that is important for inspection on the outer peripheral surface of the gauge section in order to press in the pin for pin connection of the gauge section. For this reason, the thread gauge of Patent Document 1 also has some aspects that are not desirable as a thread gauge.

[0032] Furthermore, because the gauge section 2 as a thread gauge has a complete thread 20 formed over its entire length, a tapered section for facilitating screwing, i.e., an incomplete thread with an incomplete thread, is not formed at its tip. This is because if an incomplete thread is formed, the thread cannot be inspected accurately. For this reason, simply pushing in the gauge section 2 does not provide the centering function provided by the tapered section at the tip, as with normal threads, so the gauge section 2 is centered by the centering mechanism described above in the thread gauge of this embodiment. Such an centering mechanism also reduces wear on the gauge section 2.

[0033] At this time, according to the thread gauge of this embodiment, as shown in Figure 7, in addition to the swinging of the gauge section 2, the shaft section 12 can be deflected as described above, so that the gauge section 2 can be more accurately aligned with the female threaded hole 40. That is, while the alignment in Figure 6 was performed to align the direction of the axis, alignment can also be performed to match the position of the gauge section 2 with the position of the female threaded hole 40 by deflection of the shaft section 12 in the in-plane direction in which the opening of the female threaded hole 40 is formed.

[0034] When the gauge section 2 is brought into contact with the female screw hole 40, a force acts to move the center of the gauge section 2 toward the center of the female screw hole 40 in parallel with the centering shown in FIG. 6. This force is generated by partial contact between the tip edge of the gauge section 2 and the opening edge of the female screw hole 40, and by the swinging of the gauge section 2 shown in FIG. 6. As a result, the shaft section 12 is deflected, and the centering shown in FIG. 7 is also performed. In particular, the deflection of the shaft section 12 shown in FIG. 7 is generated by a force acting on the ball point section 11 provided at the tip of the shaft section 12 via the gauge section 2, so that the shaft section 12 is easily deflected, improving the centering function. In the thread gauge of this embodiment, centering by the swinging of the gauge section 2 relative to the shaft 1 shown in FIG. 6 and centering by the deflection of the shaft section 12 shown in FIG. 7 are performed in parallel, improving the centering function.

[0035] The assembly of the above-mentioned thread gauge will be briefly described. First, the sleeve 3 is attached to the shaft portion 12 of the shaft 1. At this time, the shaft portion 12 can be inserted into the inside of the sleeve 3 through the slit 30 of the sleeve 3. After that, with the sleeve 3 positioned near the ball point portion 11, the male thread portion 32A of the sleeve 3 is screwed into the female thread portion 22A of the bottomed hole 21 using a tool, utilizing the pair of flat surfaces 33 of the sleeve 3. At this time, the portion of the flange 31 on which the flat surfaces 33 are not formed abuts against the opening edge of the bottomed hole 21, so that an axial force acts between the male thread portion 32A and the female thread portion 22A, and a fastening force is generated between the sleeve 3 and the bottomed hole 21. When the complete thread 20 of the gauge portion 2 wears and needs to be replaced, in the case of the thread gauge of this embodiment, the gauge portion 2 can be easily replaced by unscrewing the sleeve 3 and the gauge portion 2.

[0036] In this embodiment, a pair of flat surfaces 33 is formed on the flange 31, and the fastening torque required for fastening the sleeve 3 to the bottomed hole 21 is generated by a tool. However, the flange 31 may have another external shape, such as a regular hexagon, so that the fastening torque can be generated. Also, a tool may be manufactured that uses the slits 30 to generate the fastening torque without forming the flat surfaces 33 on the flange 31.

[0037] Next, a thread gauge of a second embodiment will be described with reference to FIG. 8. The sleeve 3 shown in FIG. 8 is also shown in a cross section not passing through the plane 33, as in FIG. 5. In the first embodiment described above, as shown in FIG. 5, the maximum outer diameter of the flange 31 of the sleeve 3 is formed smaller than the minimum inner diameter of the maximum outer diameter of the gauge section 2. That is, the maximum outer diameter of the flange 31 is smaller than the maximum outer diameter of the female thread 40 to be inspected, and as shown in FIG. 5, the flange 31 can also enter the inside of the female thread hole 40. On the other hand, in this embodiment, as shown in FIG. 8, the maximum outer diameter of the flange 31 is formed larger than the maximum outer diameter of the gauge section 2. That is, the maximum outer diameter of the flange 31 is larger than the maximum outer diameter of the female thread hole 40 to be inspected, and the flange 31 functions as a stopper for the female thread hole 40. The maximum outer diameter of the female thread refers to the outer diameter at the valley portion of the thread groove. Since the configuration other than the flange 31 is the same as the configuration of the first embodiment described above, the overlapping description thereof will be omitted.

[0038] Here, consider a case where the gauge part 2 is screwed into the female screw hole 40 using a machine capable of detecting the number of revolutions. In the inspection of the female screw hole 40, the depth of the female screw hole 40 may also be inspected, and by using such a machine, it is possible to detect whether the female screw hole 40 is normally formed to the desired depth from the number of revolutions and the thread pitch. On the other hand, it is difficult to detect the screwing depth when the inspection is performed manually or semi-automatically. Therefore, if the flange 31 is formed as a stopper as in this embodiment and the stopper can be screwed until it abuts against the opening edge of the female screw hole 40, it is possible to determine that the female screw hole 40 is normally formed to the desired depth. On the other hand, if the screw gauge of the first embodiment is used for inspection together with a machine capable of detecting the number of revolutions, it is also possible to inspect a deep female screw hole 40. The other effects described above brought about by the first embodiment are also brought about by this embodiment.

[0039] Next, a thread gauge of a third embodiment will be described with reference to Figures 9 and 10. In the first and second embodiments, the sleeve 3 was attached to the bottomed hole 21 by the male thread portion 32A and the female thread portion 22A. In this embodiment, a protrusion 32 is formed instead of the male thread portion 32A, and a groove 22 is formed instead of the female thread portion 22A, and the sleeve 3 is engaged with the bottomed hole 21. In this embodiment, the sleeve 3 is also made of metal. The other configurations are the same as those of the first embodiment described above, so duplicated explanations will be omitted.

[0040] In this embodiment, between the engaging portion 21a of the bottomed hole 21 and the opening, a cylindrical surface 21b is formed, the cross section of which is the circumscribing circle of the regular hexagon of the engaging portion 21a. A groove 22 for preventing the sleeve 3 from slipping out is formed on the cylindrical surface 21b in the circumferential direction over the entire circumference. A protrusion 32 that engages with the groove 22 is provided on the outer peripheral surface of the sleeve 3 in the circumferential direction over the entire circumference. However, the protrusion 32 is not formed in the portion where the slit 30 is formed. The outer diameter of the protrusion 32 is equal to or slightly smaller than the inner diameter of the groove 22. The cross-sectional convex shape of the protrusion 32 is the same as but slightly smaller than the cross-sectional concave shape of the groove 22. When the sleeve 3 is attached to the opening of the bottomed hole 21, the protrusion 32 is stored inside the groove 22, and the sleeve 3 is prevented from slipping out of the gauge portion 2.

[0041] The installation of the sleeve 3 to the opening of the bottomed hole 21 will be described. First, as in the first embodiment, the sleeve 3 is attached to the shaft portion 12 of the shaft 1. Then, in a state where the sleeve 3 is positioned near the ball point portion 11, an external force is applied to the sleeve 3 to elastically deform the sleeve 3 so that the outer diameter of the protrusion 32 becomes equal to or smaller than the inner diameter of the cylindrical surface 21b of the bottomed hole 21, and the sleeve 3 is inserted into the bottomed hole 21. When the applied external force is released, the sleeve 3 returns to its original shape by its elastic restoring force, and the protrusion 32 is stored in the groove 22. In this embodiment, too, when the complete thread 20 of the gauge portion 2 is worn and needs to be replaced, the gauge portion 2 can be easily replaced by performing the steps reverse to those described above. According to this embodiment, it is not necessary to perform the complicated thread processing of the male thread portion 32A and the female thread portion 22A of the first embodiment, and the sleeve 3 can be prevented from coming off by simply processing the protrusion 32 and the groove 22. The other effects described above brought about by the first embodiment are also brought about by this embodiment.

[0042] Next, a thread gauge of a fourth embodiment will be described with reference to FIG. 11. In this embodiment, the sleeve 3 is fixed to the gauge part 2 by press-fitting the sleeve 3 into the bottomed hole 21. In this embodiment, the sleeve 3 is also made of metal. Since the sleeve 3 is press-fitted into the bottomed hole 21, no protrusions 32 are formed on the outer peripheral surface of the sleeve 3. Furthermore, the outer diameter of the sleeve 3 is formed slightly larger than the inner diameter of the cylindrical surface 21b of the bottomed hole 21 as a tightening margin so that the sleeve 3 is fixed after press-fitting. Although not shown, it is not necessary to form the female thread part 22A or the groove 22 on the cylindrical surface 21b. The other configurations are the same as those of the first embodiment described above, so that the overlapping explanations thereof will be omitted.

[0043] The assembly method of the thread gauge is almost the same as that of the thread gauge of the first embodiment, but the attachment to the opening of the bottomed hole 21 of the sleeve 3 can be achieved by simply pressing. After the press-fitting, the width of the slit 30 is expected to narrow slightly, but this is not a problem because the shaft portion 12 is already located inside the sleeve 3. In this embodiment, a slight stress acts on the gauge portion 2 after the press-fitting, but the attachment of the sleeve 3 to the gauge portion 2 is made easier. In addition, it is not necessary to machine the male thread portion 32A and the female thread portion 22A of the first embodiment, or the protrusion 32 and the groove 22 of the third embodiment, and the sleeve 3 can be prevented from coming off. The other effects described above brought about by the first embodiment are also brought about by this embodiment.

[0044] Next, a thread gauge of a fifth embodiment will be described with reference to FIG. 12. In this embodiment, the sleeve 3 is made of resin, and the sleeve 3 is fixed to the gauge portion 2 by press-fitting the sleeve 3 into the bottomed hole 21. Since the sleeve 3 is made of resin, its elastic deformation amount is larger than that of metal. Therefore, even if the width of the slit 30 is narrowed, the slit 30 can be elastically deformed to widen the width thereof, and the shaft portion 12 can be disposed therein. The width of the slit 30 is set to a width that closes after being press-fitted into the bottomed hole 21. That is, before press-fitting, the outer diameter of the sleeve 3 is formed larger than the inner diameter of the cylindrical surface 21b of the bottomed hole 21. More specifically, the sleeve 3 is formed so that when the sleeve 3 is elastically deformed until the slit 30 closes, the outer diameter of the sleeve 3 after elastic deformation is slightly larger than the inner diameter of the cylindrical surface 21b of the bottomed hole 21 as a tightening margin. In this embodiment, it is not necessary to form the female thread portion 22A or the groove 22 on the cylindrical surface 21b. The other configurations are the same as those of the first embodiment described above, so duplicated explanations will be omitted.

[0045] The assembly method of the thread gauge is almost the same as that of the thread gauge of the first embodiment, but as described above, when mounting the sleeve 3 on the shaft portion 12, the slit 30 is widened before mounting. Also, the sleeve 3 can be attached to the opening of the bottomed hole 21 simply by press-fitting. After press-fitting, the slit 30 closes and the above-mentioned interference functions effectively, fixing the sleeve 3 to the opening of the bottomed hole 21. This embodiment also makes it easy to mount the sleeve 3 to the gauge portion 2. The other effects described above brought about by the first embodiment are also brought about by this embodiment.

[0046] The thread gauge according to the above embodiment includes a gauge section 2 in which a bottomed hole 21 is formed, a shaft 1 in which a ball point section at the tip is inserted into the bottomed hole 21, and a cylindrical sleeve 3 attached to the opening of the bottomed hole 21. Torque can be transmitted from the shaft 1 to the gauge section 2 by the ball point section 11 having a male shape capable of transmitting torque and the engagement section 21a of the bottomed hole 21 having a corresponding female shape capable of transmitting torque, and the gauge section 2 can swing relative to the shaft 1. When attached to the opening of the bottomed hole 21, the sleeve 3 has an inner diameter smaller than the maximum outer diameter of the ball point section 11 and larger than the maximum outer diameter of the shaft section 12. Therefore, a centering mechanism in which the gauge section 2 swings based on the tip of the shaft 1 and the bottom of the bottomed hole 21 can be realized with a simple structure.

[0047] Furthermore, since the gauge portion 2 swings based on the tip of the shaft 1 and the bottom of the bottomed hole 21, an excellent centering mechanism can be realized. At this time, since the ball point portion 11 is loosely fitted in the bottomed hole 21, the gauge portion 2 can swing without resistance relative to the shaft 1, and centering can be performed smoothly. Furthermore, the maximum outer diameter of the shaft portion 12 is smaller than the maximum outer diameter of the ball point portion 11, and the shaft portion 12 can bend. Therefore, the centering function due to the bending of the shaft portion 12 is added to the centering function due to the swing of the gauge portion 2 described above, and an even more excellent centering mechanism can be realized.

[0048] Furthermore, since the slits 30 are formed in the sleeve 3, the sleeve 3 can be easily attached to the shaft portion 12. In other words, the thread gauge can be constructed with a simpler structure.

[0049] Here, in the first and second embodiments, while the slit 30 is formed, a male thread portion 32A is formed on the outer peripheral surface of the sleeve 3, and a female thread portion 22A that screws into the male thread portion 32A is formed on the inner peripheral surface of the bottomed hole 21. Therefore, it is possible to reliably prevent the sleeve 3 from coming off from the bottomed hole 21.

[0050] Alternatively, in the third embodiment, in addition to forming the slits 30, protrusions 32 are provided on the outer peripheral surface of the sleeve 3 extending in the circumferential direction, and grooves 22 for accommodating the protrusions 32 are formed in the circumferential direction on the inner peripheral surface of the bottomed hole 21. Therefore, a structure for reliably preventing the sleeve 3 from slipping out of the bottomed hole 21 can be realized with a simple structure.

[0051] In the second embodiment, the sleeve 3 is formed with a flange 31 that abuts against the other end face of the gauge portion 2, i.e., the opening of the bottomed hole 21, and the maximum outer diameter of the flange 31 is made larger than the maximum outer diameter of the gauge portion 2. Therefore, since the flange 31 functions as a stopper for the female threaded hole 40 to be inspected, the depth of the female threaded hole 40 can also be inspected during manual or semi-automatic inspection.

[0052] Furthermore, in the above embodiment, since the height H of the bottom center O of the bottomed hole 21 is set within the range of the above inequality (1), the above-mentioned centering function can be reliably achieved.

[0053] The thread gauge of the present disclosure is not limited to the above-described embodiment. For example, the "male and female shapes capable of transmitting torque" in the above-described embodiment are convex and concave shapes of a regular hexagon. However, the "male and female shapes capable of transmitting torque" may be other torque-transmitting shapes such as a hex lobe or a pentalobe. It is also possible to form the ball point portion 11 in a shape such as a hex lobe or a pentalobe.

[0054] In the above embodiment, the thread gauge is formed in the form of a bit, but it may be formed in a form that is not formed in the form of a bit and is intended only for manual use. Even if it is formed in the form of a bit, the form of the chuck portion 10 is not limited to the form shown in Fig. 1 and may be formed in other forms. Furthermore, according to the thread gauge of the present disclosure, when inspecting the female threaded hole 40 fully automatically using a robot arm, the improved centering function makes it easy to accommodate full automation.

[0055] Furthermore, in the above embodiment, the shaft 1 is formed as an integral part, but the shaft portion 12 and the ball point portion 11 may be formed as an integral part, and the shaft portion 12 may be joined to the chuck portion 10 by screwing or the like. In this case, the shaft portion 12 can be inserted into the sleeve 3 before being joined to the chuck portion 10, and therefore there is no need to provide a slit 30 for passing the shaft portion 12 through the sleeve 3. However, in the case of the third embodiment in which the projection 32 and the groove 22 are engaged with each other, a slit must be formed for attachment to the opening of the bottomed hole 21 of the sleeve 3.

[0056] In the above embodiment, the sleeve 3 is prevented from coming off the gauge portion 2 by screwing the male threaded portion 32A with the female threaded portion 22A, by engaging the protrusion 32 with the groove 22, or by press-fitting the sleeve 3. However, the sleeve 3 may be fixed to the opening of the bottomed hole 21 of the sleeve 3 by bonding the sleeve 3 to the cylindrical surface 21b. [Explanation of symbols]

[0057] 1 Shaft 2 Gauge section 3 Sleeve 11 Ball point part 12 Shaft section 21 Bottomed hole 21a Engagement part 22A Female thread 22 Groove 30 Slit 31 Flange 32A Male thread 32 Protrusion 40 Female thread hole O (Bottom center of bottom hole 21)

Claims

1. A thread gauge for inspecting female threaded holes, comprising: a gauge portion having an externally threaded complete thread formed on an outer peripheral surface from one end and a blind hole formed on the other end surface; a shaft having a tip portion inserted into the bottomed hole of the gauge portion; a cylindrical sleeve attached to an opening of the bottomed hole, the shaft has a ball point portion having a male shape capable of transmitting torque at the tip portion, and a shaft portion extending from the ball point portion and having a maximum outer diameter smaller than a maximum outer diameter of the ball point portion, an engaging portion having a female shape capable of transmitting torque corresponding to the ball point portion is formed on an inner peripheral surface of the bottomed hole at least in the vicinity of a bottom portion thereof; The sleeve, when installed in the opening, has an inner diameter that is smaller than the maximum outer diameter of the ball point portion and larger than the maximum outer diameter of the shaft portion.

2. 2. The thread gauge according to claim 1, wherein a slit is formed in the sleeve from one end to the other end in the axial direction thereof.

3. A male thread portion is formed on the outer peripheral surface of the sleeve, and 3. The thread gauge according to claim 2, wherein a female thread portion is formed on an inner peripheral surface of the blind hole, the female thread portion being screwed into the male thread portion.

4. A protrusion is provided on an outer peripheral surface of the sleeve in a circumferential direction, and 3. The thread gauge according to claim 2, wherein a groove for accommodating said projection is formed in a circumferential direction on an inner peripheral surface of said blind hole.

5. a flange is formed on the sleeve to come into contact with the other end surface of the gauge portion, 5. The thread gauge according to claim 1, wherein the maximum outer diameter of the flange is greater than the maximum outer diameter of the gauge portion.

6. 6. The thread gauge according to claim 1, wherein, when the maximum outer diameter of the gauge portion is D, a height H from one end face of the gauge portion to the center of a bottom surface of the blind hole is within a range of 0.2D≦H≦D / [2(3^(1 / 2)].

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