JPH0776692B2 - Pitch inspection method and device for internal thread - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for inspecting a pitch of a screw, especially a pitch of a female thread, which enables inspection at a production site by utilizing air pressure.

[Conventional technology]

Conventionally, the eighth method has been used to measure the pitch of female threads such as nuts.
There has been a method of using a precision screw measuring device 40 (for example, a device attached to a universal comparator made by Rights Co., Ltd.) 40 as shown in the figure. This device includes a measuring sleeve 41 that can move up and down, a cellometer, a micrometer for measuring vertical movement,
It has a built-in precision standard scale, standard scale reading objective lens, and lighting system. And in order to measure the pitch of the female screw, the axis line adjustment of the female screw 43 to be measured set on the platform 42 whose tilt angle can be adjusted as shown in the figure uses the feeler 44 and the ball 45 attached to this, and the zero indicator Eyepiece
After looking through 46, hit the ball 43 of the feeler against the flank surface of the female thread, look through the eyepiece lens 47 of the micrometer, read the value, and then hit the ball on the flank surface that is shifted up or down by one pitch. The value is read through the meter eyepiece lens 47, and the difference between the two read values is used as the pitch measurement value. Such a method is repeated over the entire length of the screw.

However, this method requires a long measuring time and a considerable measuring skill, and is not suitable for a production site.

There is a method using a limit screw plug gauge as a comprehensive system inspection of the female screw currently used at the production site.

The accuracy inspection method using this limit screw plug gauge uses two types of screw plug gauges, the passing side and the stopping side, and determines the total effective diameter of the screw on the passing side of the specified fitting length (JISB3102) and on the stopping side. The individual effective diameter of the screw is inspected, and the thread gauge on the passing side of those thread gauges passes through without difficulty, and when the thread gauge on the stop side cannot be screwed in more than 2 turns, the thread (female thread) is inspected by the thread gauge. It is determined to have passed.

[Problems to be solved by the invention]

However, in such a conventional internal thread accuracy inspection method at a production site, since a limit thread gauge is used, various limit thread gauges must be prepared corresponding to the grade of the internal thread. There was a flaw. Further, since the accuracy inspection by this method is a comprehensive inspection, there is a drawback that it is not possible to separately measure the pitch, the effective diameter, the half-angle of the mountain and the like. Screws are also used in various technical fields, and it is indispensable to be able to control the pitch of internal threads in order to stabilize the fatigue strength, especially when safety of aircraft etc. is required, and the demand for it is also increasing. It was

[Means for solving problems]

The present invention has been made in view of such conventional problems and demands, and a gap between an object to be inspected (nut etc.) is provided by four jet holes provided on the flank surface of the male thread portion of the screw nozzle body. It is an object of the present invention to solve the above-mentioned problems by measuring the respective values using the air pressure in the measuring section and calculating these measured values.

〔Example〕

 The present invention will be described below with reference to the drawings.

FIG. 1 is a side view showing an embodiment of the present invention and a block diagram showing a measuring system. First, the structure will be described. 1 is a screw nozzle body having a guide portion 4 on the upper side, a male screw portion 3 on the center, and a shaft portion 7 on the lower side. The guide portion 4 is a guide portion of a female screw pitch master 5 (shown by a dotted line). 6 is formed so as to rotate in a sliding state. The male screw portion 3 is formed so as to be coaxial with the guide portion 4, and the flank surface 8 of the male screw portion 3 is provided with jet holes 9a, 9a ', 9b, 9b' at an appropriate position upward and symmetrically with respect to the axis. Provided in parallel, and further the male screw part 3
2 with jet holes 9a, 9b and 9a ', 9b' in between
A total of four air escape grooves 10a, 10a '(not shown) 10b, 10b'
Is formed so as to communicate with the shaft portion 7 from the guide portion 4.
The shaft portion 7 is formed so as to be coaxial with the male screw portion 3, a collar portion 11 is provided in the center, and the lower end of the shaft portion 7 is connected to the main air passages 12a, 12a 'by joints 13, 13'. Are formed. Further, main air passages 12a, 12a 'are provided inside the screw nozzle body 1 so as to communicate with the joints 13, 13'. 14 is a measuring instrument such as an air micrometer, which is a joint 13, 13 '
To the jet surface 25a, 2 of the jet holes 9a, 9a ′, 9b, 9b ′.
This is a part for detecting and measuring the gap between 5a'25b and 25b '.
The internal structure of the measuring unit 14 will be described in FIG. 7, R _1, R ₂
Is a part that reduces the air pressure input from the air source to a constant pressure by a regulator (pressure reduction control unit). Also 26a, 26b
Is a magnification adjusting diaphragm, and 27a and 27b are zero adjusting diaphragms, respectively, for the clearances H ₁ and H _{2 of the} jets 29a and 29b, respectively.
A diaphragm for aligning the pointers 31a and 31b of 30. 28a and 28b are pneumatic circuits for forming circuits independently.
Reference numeral 15 is a filter, 16 is an air supply source, and 20 is a pedestal for vertically fixing and holding the screw nozzle body 1.

FIG. 2 is an enlarged cross-sectional view taken along the line AA of FIG. 1, and when explaining the details of the screw nozzle body 1 in this figure, the main air passage 12
The a is formed to communicate with the air passage 12b and the air passage 12c, and the main air passage 12a 'is also formed to communicate with the air passage 12b' and the air passage 12c '. Further, auxiliary air passages 17a and 17c are provided at the ends of the air passages 12c and 12c ', respectively.
A'and 17b are formed so as to communicate with each other.

18a, 18b, 18a ', 18b' and 19a, 19a ', 19b are plugs for forming a pneumatic circuit, respectively.

In addition, jet holes 9a, 9a 'and 9b, 9b' are formed at appropriate positions above the flank surface 8 of the male threaded portion 3 symmetrically with respect to the axis and formed in parallel with a shift of 1 pitch in the axial direction. Further, the jet holes 9a, 9a 'and 9b, 9b' are formed to communicate with the auxiliary air passages 17a, 17a 'and 17b, respectively.
The air escape groove 10 is formed at the tip of the jet holes 9a, 9a ', 9b, 9b'.
Jet surfaces 25a, 25a ', 2 partitioned by a, 10a', 10b, 10b '
5b, 25b ′ are appropriate steps Ha, Ha ′, Hb, H with respect to the flank surface 8.
b'is provided. Further, FIG. 5 is a plan view of the pitch master and the screw nozzle body of FIG. 1, and 21a and 21b show the upper surface of the pitch master 5 and the screw for rotating the pitch master 5 to align with the screw nozzle body 1. It is a marking line provided on the guide portion 4 of the nozzle body 1.

Next, the operation will be described. FIG. 3 is a diagram showing the basic principle for inspecting the pitch. This principle will be explained with reference to the same drawing. 1 is a screw nozzle body, 9a, 9a ', 9b, 9b' are jet holes, 12, 12 ′ Is an air passage, 2 is a female screw to be inspected, △ a ₁ ,
△ a ₂ , △ b ₁ , △ b ₂ are the axial clearances between the female screw to be inspected and the jet hole, and the pitch error ε is calculated from this: ε = 1/2 {(△ a ₁ + △ a ₂ )-(△ b ₁ + △ b ₂ )} is established, and therefore the values of the gaps △ a ₁ + △ a ₂ and △ b ₁ + △ b ₂ are read using an air micrometer and the like. The pitch error ε will be obtained from the difference.

Therefore, in this embodiment, two screw air passages and two pneumatic passages are communicated with each other inside the screw nozzle body, and they are arranged 180 ° opposite to the flank surface of the male screw portion, and jet holes formed in parallel are provided. Therefore, by simply screwing the object to be inspected (nut etc.) into the threaded portion of the screw nozzle body, the pitch of the female thread, which was previously considered difficult to test independently, can be easily tested in a short time. Furthermore, it corrects the posture error of the object to be inspected, which guarantees highly accurate inspection of the pitch of the female screw. The explanatory view shown in FIG. 4 is an enlarged view showing the change in the gap between the jet holes 9a, 9b and the pitch master 5 (in this figure, the master whose pitch is slightly larger than the reference pitch). The dotted line shows the moving position when the pitch master is rotated once. Observing the gap at each jet position, if the amount of the gap a of the pitch master which is larger than the reference pitch P by a certain amount α in the jet hole 9b is H, the gap c in the jet hole 9a is shifted by one pitch. Because
2H, and when looking at the gap when the pitch master is rotated once to the position indicated by the dotted line, the increment b of the jet hole 9b is a shift corresponding to one pitch, and is the same as the gap a.
In the jet hole 9a, the increment d of the gap becomes H because it is still a shift corresponding to one pitch. Therefore jet hole 9b
It means that the gap of H has changed from H to 2H, and the gap of the jet hole 9a has changed from 2H to 3H. From this fact, the display of the measuring instrument should be adjusted as follows.

That is, further describing this embodiment, the screw nozzle body 1 is attached to a pedestal 20 (shown by a dotted line), the screw nozzle body 1 is set upright, and is provided at the lower end of the shaft portion 7 of the screw nozzle body 1. The couplings 13 and 13 'and the pneumatic circuit of the measuring instrument 14 are connected to each other to provide two pneumatic circuits. Next, if air is supplied from the air supply source 16, the air will be filtered.
After passing through 15, the measuring instrument 14, the screw nozzle body 1 from the joints 13 and 13 ', and the jet holes 9a, 9a' and 9b, 9b 'through the main air passage and the auxiliary air passage, one circuit at a time. Independent pneumatic circuits are formed, allowing the measurement of each pneumatic pressure. Now, regarding the internal thread pitch inspection method, since air is flowing out from the jet holes 9a, 9a ', 9b, 9b' of the screw nozzle body 1, first insert the internal thread pitch master 5 from the upper part of the screw nozzle body 1, Rotate from the upper end of the male screw part 3 and screw in (the position of the pitch master in the axial direction should be indicated appropriately on the display of the measuring instrument) Reference position (5th
At the engraved position in the figure), set the indication of the stop measuring instrument 14. At that time, the pitch of the pitch master is, for example, +15 with respect to the reference pitch.
The case of μm (α) will be described as an example with reference to FIG. FIG. 6 is a view showing the positional relationship of the pointers on the scale plate, 22 is a scale plate 23 is a black needle, 24 is a red needle is a jet hole
Assuming that the pneumatic circuit of 9b, 9b 'is the R line and the pneumatic circuit of the jet holes 9a, 9a' is the S line, the display of the R line is such that the black needle right 15 turns to the black needle 0 when the master makes one revolution. Match the magnification of. Since the jet portion of the S line is displaced by one pitch, the line is shifted by 15 μm (α ′), and the magnification is adjusted so that the master rotates once from the red needle to the left red needle of 15 μm (α ′). This completes the adjustment of the magnification (adjustment of the range of the pointer) in the pitch master measuring device, and then the measured object (nut etc.) is screwed into the male thread part 3 of the screw nozzle body 1 and the pointer (black needle, red needle)
If you read the difference, the value becomes the pitch error. Next, the relationship between the relative position of the pointer and the pitch error will be described. First, if the black and red needles overlap at any position, there is no pitch error. When the black needle is located to the right of the red needle, the pitch error is a plus error with respect to the reference pitch, and when the black needle is located to the left of the red needle, the pitch error is minus with respect to the reference pitch. Incidentally, the steps Ha, Ha ', Hb, Hb' of the jet surfaces 25a, 25a ', 25b, 25b' of the male screw part 3 in FIG. 2 are inspected by providing a gap even if the pitch of the object to be inspected is the same as the reference pitch. Is to enable.

Therefore, according to this embodiment, two screws are provided inside the screw nozzle body.
Since the air passages of the book and the air passages are respectively communicated with each other, and the flank surfaces of the male threads are located 180 degrees opposite to each other, the jet holes formed in parallel are provided.
It is possible to easily and quickly inspect the pitch of the female screw, which was previously difficult to inspect by itself by simply screwing the inspected object (nut, etc.) into the thread portion of the screw nozzle body. This guarantees a highly accurate internal thread pitch inspection to correct the posture error of the object. In addition, the structure is such that an appropriate step is provided on the jet surface of the screw part, and the screw nozzle body is fixed upright on the pedestal, so the stability of the screw nozzle body is good and the workability of screwing in the inspected object is improved. It is also excellent, and since the flank surface of the female thread of the object to be inspected faces the flank surface of the thread part of the screw nozzle body with a gap, accurate pitch measurement can be performed regardless of the effective diameter of the female thread. Moreover, abrasion of the jet surface is prevented and stable measurement for a long period of time is possible.

Further, there is an advantage that the pitch error can be inspected at any position by screwing the inspection object into the external thread portion of the screw nozzle body and rotating the inspection object.

[Outline of Invention]

As described above, according to the present invention, one flank surface of a screw nozzle body having a male thread portion of a reference pitch is communicated with two jet holes symmetrically provided with respect to an axis, and the jet hole is connected to one of the measuring instruments. Connected to the pneumatic circuit of each of the two jet holes on the same flank surface in the axial direction.
Two jet holes, which are arranged symmetrically with respect to the axis with a pitch shift, are connected, the jet holes are connected to the other pneumatic circuit of the measuring instrument, and the female screw to be measured is screwed into the male screw part of the screw nozzle body. , Air is supplied from the air source to each of the pneumatic circuits, and the air is jetted to the flanks on the female screw side facing each other through the four jet holes, and the four jet holes and the flanks on the female screw side are formed. Each of the axial gaps Δa ₁ , Δa ₂ , Δb ₁ and Δb ₂ is measured, and the pitch ε is calculated by the following equation: ε = 1/2 {(△ a ₁ + △ a ₂ )-(△ b ₁ + Δb ₂ )} is a method and an apparatus for inspecting a pitch of a female screw, which is characterized by:

〔The invention's effect〕

As described above, according to the present invention, the structure is communicated with two air passages inside the screw nozzle body and the pneumatic circuit thereof, respectively, and is located 180 degrees opposite to the flank surface of the male screw portion, Since the structure is such that the jet holes formed in parallel are provided, the pitch of the female thread, which has been considered difficult to test independently until now, simply by screwing the object to be inspected (nut, etc.) into the threaded portion of the screw nozzle body. Can be inspected easily and in a short time. Further, since the posture error of the object to be inspected is corrected, highly accurate inspection of the pitch of the female screw is guaranteed.

In addition, the magnitude and positive / negative of the pitch error can be immediately known by observing the display of the pneumatic circuit of the measuring instrument, so that it is possible to inspect at the production site and, therefore, it is possible to immediately take countermeasures against the processing of the female screw.

Furthermore, in the case of measurement and inspection using air, there is a conventional large range,
In principle, the display of the measuring instrument was adjusted by using two kinds of masters, but when the configuration and method of the present invention were used, the pitch was deviated by a known amount from one kind of reference pitch. The master can adjust the display of the measuring instrument, which has excellent work efficiency and can be manufactured at low cost.

Further, as described above, the pitch can be inspected with the minimum clearance regardless of the effective diameter of the female screw of the object to be inspected, so that the inspection can be performed even if the diameter of the jet hole is small, which is a great effect on the pitch inspection of the female screw. It is a thing.

[Brief description of drawings]

FIG. 1 is a side view showing an embodiment of the present invention and a block diagram of a measuring system, FIG. 2 is an enlarged sectional view taken along the line AA of FIG. 1, and FIG. 3 is for inspecting the pitch of an internal thread. FIG. 4 is an explanatory view showing the basic principle, FIG. 4 is an explanatory view showing a change in the gap between the jet hole and the pitch master, FIG. 5 is a plan view showing the pitch master and the screw nozzle body in FIG. 1, and FIG. 6 is a measurement. FIG. 7 is a diagram showing a positional relationship of pointers on a scale plate of the instrument, FIG. 7 is a circuit diagram showing a gap relationship between a measuring instrument and a jet hole, and FIG. 8 is an explanatory diagram showing an example of a conventional pitch measuring method. 1 ... Screw nozzle body, 2 ... Female thread to be inspected 3 ... Male thread part, 4 ... Guide part 5 ... Pitch master, 6 ... Guide part 7 ... Shaft part, 8 ... Frank surface 9 ... Jet Hole, 10 ... Air escape groove 11 ... Collar part, 12 ... Main air passage 13 ... Fitting, 14 ... Measuring instrument 15 ... Filter, 16 ... Air source 17 ... Auxiliary air passage, 18 ... Plug 19 ... Plug, 20 ... Receptacle 21 ... Engraved line, 22 ... Scale plate 23 ... Black needle, 24 ... Red needle 25 …… Jet surface, 26 …… Magnification adjustment diaphragm 27 …… Zero adjustment throttle, 28 ...... Pneumatic circuit 29 ...... Jet, 30 ...... Display 31 …… Pointer, 40 …… Precision screw measuring device 41 …… Measuring sleeve, 42 …… Base 43 …… Female thread to be measured, 44 …… Feeler 45 …… Ball 46 …… Zero indicator eyepiece 47 …… Micrometer eyepiece

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References Japanese Patent Publication No. Sho 57-46482 (JP, B2) Actual Publication No. Sho 58-18981 (JP, Y2)

Claims (4)

[Claims] 1. A flank surface of a screw nozzle body having a male thread portion of a standard pitch is communicated with two jet holes provided symmetrically with respect to an axis, and the jet holes are connected to one pneumatic circuit of a measuring instrument. Connected to each other, and two jet holes provided symmetrically with respect to the axis with a pitch of 1 pitch in the axial direction are communicated with the two jet holes on the same flank, and the jet holes are connected to the measuring instrument. Connected to the other pneumatic circuit, screw the female screw to be inspected into the male screw part of the screw nozzle body, supply air to each pneumatic circuit from the air source, and face each through four jet holes. To the flank surface on the side, and each of the four jet holes and the flank surface on the female screw side has an axial gap Δ
a ₁ , △ a ₂ , △ b ₁ and △ b ₂ are measured, and the pitch error ε is calculated by the following equation ε =
1/2 ((Δa ₁ + Δa ₂ )-(Δb ₁ + Δb ₂ )}) 2. Two flanks of a screw nozzle body having a standard pitch male thread are communicated with two jet holes provided symmetrically with respect to an axis, and the jet holes are connected to one pneumatic circuit of a measuring instrument. 2 on the same flank surface
Two jet holes symmetrically provided with respect to the axis with a pitch of 1 pitch in each axial direction are connected to each of the jet holes, the jet holes are connected to the other pneumatic circuit of the measuring instrument, and the pitch is adjusted in advance. A female thread pitch master deviated by a known amount (α) from the reference pitch is screwed into the male thread portion of the nozzle body, air is supplied to each pneumatic circuit from an air source, and the air is supplied through the four jet holes. When each of them is jetted to the flank surface on the female screw side facing each other, the displacement of each pneumatic circuit of the measuring instrument is adjusted to (α ′) with respect to the displacement of one pitch of the female screw pitch master, The display displacement of one pneumatic circuit of the measuring instrument is shifted in the displacement direction by (α ') with respect to the display displacement of the other pneumatic circuit, and after that, the female screw pitch master is replaced and the female screw to be inspected Pitch inspection method of the internal thread, characterized in that screwed into the threaded portion, the pitch error with the difference between the display of both the pneumatic circuit. 3. A jet nozzle body having a male thread portion of a standard pitch is provided with two jet holes, which are symmetrical with respect to an axis and connected to a pneumatic circuit of a measuring instrument, on one flank surface of the male thread portion. In the same flank surface, two jet holes which are symmetrical with respect to the axial center and are connected to the pneumatic circuit of the measuring instrument with a pitch of 1 pitch in the axial direction with respect to the two jet holes are provided, and the male screw portion is provided. The pitch inspection device for female threads is characterized in that the air escape groove is formed in the axial direction by sandwiching the jet hole. 4. Two jet holes, which are symmetrical with respect to an axial center on one upper flank surface of the male thread portion of a screw nozzle body having a male thread portion of a reference pitch, and which are connected to a pneumatic circuit of a measuring instrument. And the above-mentioned 2 on the same upper flank surface.
Two jet holes, which are symmetrical with respect to the axis with a pitch of 1 pitch each in the axial direction and are connected to the pneumatic circuit of the measuring instrument, are provided in the male screw portion, and the male screw portion is provided with the jet hole. And an air escape groove is formed in the axial direction of the jet hole, an appropriate step is provided on the jet surface of the jet hole, and the screw nozzle body is held upright on a pedestal. .