JPH11183153A - Screw working inspection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a screw working inspection method which can simply inspect whether screw working is performed. SOLUTION: In a screw working inspection method for inspecting whether screws 3, 9 are worked on cylindrical parts 2, 8 of a member, the following are contained; a reference value measuring process for detecting the outputs of air micrometers when the diameters of the cylindrical parts are measured with the air micrometers, a screw part measuring process for detecting the outputs of the air micrometers when the diameters of the cylindrical parts of members for which whether screw working is performed is inspected are measured, and a comparison process which compares the outputs of the air micrometers in the reference value measuring process and the screw part measuring process, and judges that the screw working is performed, when difference larger than or equal to a given amount exists.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a threading inspection method for inspecting whether a surface of a pilot hole or a cylindrical object is threaded.

[0002]

2. Description of the Related Art Screws are widely used as mechanical fastening means. FIG. 1 is a diagram illustrating the processing of a screw.
As shown in FIG. 1A, in the case of a female screw, a prepared hole 2 having a predetermined diameter is formed in the member 1, and a screw 3 is formed on an inner wall of the prepared hole 2. As shown in FIG. 1 (2), in the case of a male screw, after processing the cylindrical portion 8 to a predetermined diameter,
A screw 9 is formed. Such a manufacturing method is also applied to a case where a female screw or a male screw is formed on a general-purpose screw component such as a screw, a bolt, a nut or the like for a non-general-purpose specific component. General-purpose screw parts such as screws, bolts, and nuts are mass-produced with dedicated manufacturing equipment. 100% inspection was performed with a dedicated inspection device that detects and traces, and it was inspected by extracting and matching with the master screw whether the screws were processed as specified. When a screw is formed on a part for a specific application that is not a general purpose, the shape and position of the screw differ depending on the part, so it is difficult to inspect with a dedicated inspection device like a general-purpose screw. Is common.

[0003]

It is desired to automate the machining process also for thread machining, but it is difficult to completely automate the threading process as long as a visual inspection is performed. However, as described above, when a screw is formed on a part for a specific purpose that is not a general purpose, there is currently no better inspection method than visual inspection. Therefore, it has been desired that whether or not threading is performed can be automatically measured with a simple configuration. Also, in the inspection of general-purpose screw parts such as screws, bolts and nuts, the process of contacting the stylus of the detector with the screw part and tracing is time-consuming and costly. Was.

[0004] An object of the present invention is to realize a threading inspection method capable of easily inspecting whether or not threading is performed.

[0005]

In order to achieve the above object, the method for inspecting threading according to the present invention uses an air micrometer. The output when measuring the diameter of the cylindrical portion before processing the screw with an air micrometer is different from the output when measuring the diameter with the same air micrometer after processing the screw on the cylindrical portion. Therefore, the presence or absence of thread processing is determined by measuring the portion where the screw is formed with an air micrometer and determining which state the output corresponds to.

That is, the thread working inspection method of the present invention
A threading inspection method for inspecting whether a thread is applied to a cylindrical portion of a member, and a reference value measuring step of detecting an output of the air micrometer when measuring the diameter of the cylindrical portion with an air micrometer, Compare the output of the air micrometer in the screw part measurement process, which detects the output of the air micrometer when measuring the diameter of the cylindrical part of the member to be inspected for threading, and the reference value measurement process and the screw part measurement process And a comparing step of determining that threading has been performed when there is a difference of not less than a predetermined amount.

The method of the present invention is applicable to both internal and external threads. Further, a step of relatively moving the air micrometer relative to the cylindrical portion in the axial direction of the cylindrical portion, and a step of measuring the length of the screw of the cylindrical portion from a change in the output of the air micrometer in response thereto. The provision makes it possible to check whether the screw is machined to a predetermined length.

The method for inspecting threading according to the present invention uses an air micrometer, so that the inspection can be carried out substantially in a non-contact manner. In the case of a female screw, the air micrometer is positioned so as to be located inside the screw hole. In the case of a male screw, it is only necessary to move the screw relatively so that the screw is located inside the air micrometer, and the inspection can be performed at high speed with a simple mechanism.

[0009]

FIG. 2 is a view showing an example of an air micrometer used in an embodiment of the present invention. (1) is an example of an air micrometer for measuring the inner diameter, and (2) is a depth. (3) is an example of an outer diameter measurement air micrometer. The air micrometer measures the size of the gap between the jet and the surface to be measured by utilizing the fact that the flow of air ejected from the jet changes according to the size of the gap between the jet and the surface to be measured. It measures the height. In the case of the air micrometer for measuring the inner diameter shown in FIG. 2A, the jet 10 having the tip 11 smaller than the diameter of the cylindrical hole to be measured.
And insert it into the hole. As shown in the drawing, air supplied from an air source (not shown) is supplied to the jet 10 via the A-E converter 13 and the hose 12 by the regulator 14 so that the air is jetted from the tip 11. . The diameter of the distal end portion 11 is determined, and the gap between the distal end portion 11 and the wall of the hole facing the distal end portion 11 changes according to the diameter of the hole. When the gap is narrow, the air ejected from the tip 11 becomes difficult to flow, and when the gap is wide, the air ejected from the tip 11 easily flows. The change of the air flow condition is determined by the AE converter 1.
In step 3, the signal is converted into an electric signal, amplified by the amplifier 15, and output. Thus, this output is in a predetermined relationship with the diameter of the hole.
There are various methods for detecting a change in the state of air flow, such as a differential pressure type and a flow rate type. Air micrometers are widely known and will not be described here, but the present invention uses any type. You may.

FIG. 2 (2) is a modification of the example (1), in which the jet 10 is modified. A nozzle is provided on the bottom surface of the tip portion 16. When this bottom surface is brought closer to the opposing surface, the flow of the ejected air changes according to the distance between them. Therefore, the air flow condition is detected by the AE converter 13 as in (1). (3) in FIG. 2 is obtained by changing the jet 10 to the outer diameter measuring jet 17 in the example of (1), and is the same except that the jet and the object to be measured have the opposite relationship of (1).

FIG. 3 is a diagram showing an example of measuring a non-penetrating set screw using the jet of FIG. 2 (2). As shown in FIG. 3A, the tip 16 of the jet 10 is inserted into the set screw. (2) in FIG.
It is a graph which shows the example of a change of the output of an air micrometer according to insertion depth, and a solid line shows a case where a screw is formed to a predetermined position, and a broken line shows a case where a screw is not formed. When the tip of the jet 10 approaches the entrance of the hole, the output starts to decrease. When the jet 10 is further inserted into the state as shown in FIG. 3A, the output when the screw is formed has a larger gap with the jet 10 than when the screw is not formed. The output is greater than when no screw is formed. Therefore, it is possible to detect whether or not a screw is formed. Since it is a blind screw, the screw is only partially formed. Therefore, when the thread is formed, when the jet 10 is further inserted and the tip exceeds the portion where the thread is formed, the output decreases, and eventually the same output as when no thread is formed. Therefore, if the position where the output starts to decrease is detected, the length of the screw can be detected.

FIG. 4 is a flowchart showing a process for judging whether or not a screw is formed and detecting the length of the screw by the method shown in FIG. In step 101, the jet 10 suitable for the screw hole to be inspected is selected. In step 102, a component having only the pilot hole 5 and no screw 6 is prepared, the jet 10 is inserted into the pilot hole 5, and the output of the air micrometer at that time is detected and stored. In step 103, a component in which the screw 6 is formed in the pilot hole 5 is prepared, the jet 10 is inserted into a state as shown in FIG. 3A, and the output of the air micrometer at that time is detected and stored. I do. In step 104, the intermediate level between the two outputs stored in steps 102 and 103 is stored as a threshold. Steps 101 to 104 above
Is a preparation process, which is performed before starting the inspection operation.

Steps 105 to 108 are steps performed in the thread processing line. In step 105, the jet 10 is inserted into the hole to be measured for inspecting whether or not the thread has been machined, as shown in FIG. 3A, and the output of the air micrometer is detected. In step 106, it is determined whether the output at this time is larger or smaller than the above threshold. If it is small, the screw is not processed,
It is determined that the screw is not formed. If the size is larger, the process proceeds to step 107 because the screw has been machined.
To detect the position where the output decreases as shown in FIG. 3 (2). Since the screw has been formed to this position, it is determined in step 108 whether the depth of the screw is equal to or greater than a predetermined value. If it is sufficient, it is determined to be good. Steps 105 to 108 are performed for all holes to be inspected.

FIG. 3 shows an example of measuring a set screw.
FIG. 5 is a diagram showing an example of measuring a penetrating screw. As shown in FIG. 5, in this case, a jet 10 having a tip portion 11 having the shape shown in FIG. 2A is used. In this case, too, depending on whether the screw is formed or not,
Since there is a difference in the output of the air micrometer, it is determined whether or not a screw is formed based on the level of the output.
Also, as in the case of the above-described example described with reference to FIG. 3, in the case of a through screw in which a screw is partially formed, the output changes in the middle when the insertion amount is changed. Can be.

The example of the female screw has been described above. In the case of the male screw, the jet 1 having the shape shown in FIG.
If 7 is used, the measurement can be performed similarly.

[0016]

As described above, according to the present invention,
Since it is possible to measure whether or not the screw is formed by the contact, it is possible to automatically perform the inspection that has been performed visually until now at high speed.

[Brief description of the drawings]

FIG. 1 is a view for explaining screw processing;

FIG. 2 is a diagram illustrating an example of an air micrometer.

FIG. 3 is a diagram showing a state of measurement and a change in output of an air micrometer in an example of the present invention.

FIG. 4 is a flowchart showing a process for inspecting whether or not a thread has been processed by the measuring method shown in FIG. 3;

FIG. 5 is a diagram showing a state of measurement in another embodiment of the present invention.

[Explanation of symbols]

 2 ... pilot hole 3 ... screw 10 ... jet 11, 16 ... nozzle part 13 ... AE converter 14 ... regulator

Claims (2)

[Claims] 1. A threading inspection method for inspecting whether a cylindrical portion of a member is threaded, and detecting an output of the air micrometer when measuring a diameter of the cylindrical portion with an air micrometer. A reference value measuring step, a screw part measuring step of detecting an output when the diameter of the cylindrical portion of the member to be inspected for threading is measured by the air micrometer, a reference value measuring step, and the screw part measuring Comparing the output of the air micrometer in the step, and determining that the thread has been machined when there is a difference of not less than a predetermined amount. 2. The method according to claim 1, wherein the air micrometer is moved relative to the cylindrical portion in an axial direction of the cylindrical portion. A thread working inspection method further comprising a step of measuring a length of a screw of the cylindrical portion from a change in output.