JP2017166941A - Screw inspection apparatus and method for inspecting screw using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low cost screw inspection apparatus capable of reducing the physical and mental fatigue of an inspector responsible for screw visual inspection and surely preventing a product lot including a defective from being shipped to the market.SOLUTION: A screw inspection apparatus (1) comprises: means (3) for holding and rotating an object (2) to be inspected; means (4) for imaging an image showing the appearance of the screw of the rotating object to be inspected; means (5) for calculating the area S of a bright area included in the image; means (6) for determining that the object to be inspected is disqualified when the area S is larger than or equal to a preset threshold value S0; and means (7) for notifying the determination when determined that the object to be inspected is disqualified.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a screw inspection apparatus, and more particularly, to a screw inspection apparatus that can easily and quickly inspect the appearance of a screw formed on a screw-type pipe joint, and a screw inspection method using the same.

  A screw-type malleable cast iron pipe joint (hereinafter referred to as “screw-type pipe joint”) defined in the Japanese Industrial Standard JIS B 2301 is made of malleable cast iron, and has a pipe taper thread ( This is a pipe joint in which a male thread or a female thread is formed. When using a screw-type pipe joint, the pipe and the pipe joint are joined by screwing the thread formed on the pipe end into the joint of the pipe joint. Since the thread of the taper screw for a pipe is on the outer surface or the inner surface of the cone, the joining force increases as the pipe end is screwed into the pipe joint, and a reliable joining without fluid leakage can be realized.

  In a screw-in type pipe joint, generally, sealing is performed only by fastening a joining screw without providing an independent sealing member, or a joining screw is provided after a sealing member (tape-like sealing material or liquid sealant) is provided on a threaded portion. Conclude. In any case, it is important to ensure that the thread of the pipe joint is accurately formed according to the standard in order to achieve a leak-free seal. As an inspection method for inspecting whether or not the thread of a pipe joint is accurately formed according to a standard, for example, a method for inspecting an inner diameter, an outer diameter, an effective diameter, and the like using a limit gauge is known.

  In the thread inspection, in addition to the dimensional inspection using the limit gauge, an appearance inspection for assuring the appearance of the product may be performed. The appearance inspection refers to an inspection in which an operator observes a screw thread with a pipe joint in hand and confirms that a defective product having a defect or the like is not included in the screw thread. In order to maintain the quality at a certain level in the appearance inspection, for example, there is a method of preparing a limit sample of defective products and determining a product in which an abnormality exceeding the limit sample is found as a defective product. ing.

  An inspection method using an inspection device that combines a camera and an image processing device has been developed as an inspection method capable of selecting and removing defective products faster and more accurately than visual inspection that relies on human vision. For example, in Patent Document 1, when a plurality of images of a male screw are captured while rotating a bolt, and light is irregularly reflected due to illumination of a dent or a scratch on the bolt, the bolt is regarded as a defective product. An invention of an inspection apparatus for sorting is described.

  Further, for example, in Patent Document 2, when an image of a screw is binarized because the image is taken from obliquely above the opening end side of the female screw molded part, and the area of the light receiving surface of the female screw decreases beyond a threshold value, The invention of an inspection apparatus for determining a defective product having a low female screw thread and an enlarged inner diameter is described.

  On the other hand, with regard to visual inspection by eye, an inspection method has been proposed that is less overlooked and less inspector fatigue. For example, in Non-Patent Document 1, instead of the conventional central visual inspection using the focus of the eye, the peripheral visual inspection is performed for a short time using peripheral vision. It is described that it is possible to reduce oversight of defects and fatigue.

JP 2014-109456 A JP 2007-304011 A

Takahiro Sugawara, 6 others, “Proposal for creating a new peripheral vision visual inspection focusing on effective visual field range and viewing angle for each defective item”, Journal of Japan Society for Management Engineering, April 2011, Volume 60, No. 4, p. 154-163

  The above-mentioned peripheral visual inspection is an excellent inspection method in that it does not require special equipment investment and can improve the accuracy and efficiency of visual inspection only by enhancing the inspection skill of the inspector through training. I can say that.

  However, since the appearance defect of a product is a defect that anyone can understand at a glance, if a defective product is found at the delivery destination for a product lot that has been shipped without being sorted, the lot There is a risk that the overall quality may be suspected or the trust of the supplier to the manufacturer may be lost. For this reason, inspectors tend to focus their inspection work to avoid overlooking any defective products, and even if they employ peripheral visual inspection, they can avoid the mental fatigue that comes from inspector pressure. It is difficult to reduce.

  Moreover, when the screw is provided on the outer peripheral surface of the screw-in type pipe joint, all the screw threads cannot be visually recognized unless the pipe joint is rotated. For this reason, it is necessary for the inspector to inspect the appearance of the screw thread while rotating the pipe joint by hand, and the burden on the hand and the shoulder is great. In particular, in the case where screws are provided at both ends of the pipe joint, the pipe joint must be rotated twice in order to visually inspect each of the male threads at both ends. There is a problem that it is easy to accumulate and long-term appearance inspection cannot be performed.

  For the above problem, for example, it is conceivable to employ 100% inspection using the inspection apparatus disclosed in Patent Document 1 and Patent Document 2. However, these inspection devices are not configured to inspect the threaded portion of the screw-type pipe joint without gaps. Therefore, since there is a possibility of overlooking a defect or the like existing in the thread, these inspection devices cannot be directly applied to the appearance inspection of the screw-type pipe joint.

  In addition, the conventional inspection devices disclosed in Patent Document 1 and Patent Document 2 are designed to include a mechanism for sequentially transporting the inspection object to the imaging unit for the purpose of performing automatic driving without human intervention. ing. For this reason, it is a large-scale apparatus with a large installation area, and is not suitable for the inspection performed in parallel with the visual inspection work by the eyes. Also, the price of the inspection device is generally expensive.

  The present invention has been made in view of the above-described problems. A screw inspection apparatus having a small installation area, a compact and low cost, which can reduce the fatigue of the inspector by complementing the appearance inspection by the inspector, and It aims at providing the inspection method of a screw using it.

  As a result of diligent research, the present inventors have taken an image representing the appearance of a screw while rotating the screw-type fitting as a means for inspecting the appearance of the screw provided in the screw-type fitting without overlooking. I thought it was effective. And more specifically, it is found that a highly reliable inspection method can be established by calculating the area of the bright region included in the captured image and comparing the area with a reference value to determine pass / fail. The present invention has been completed.

  That is, the present invention is a screw inspection apparatus for inspecting the appearance of a screw formed on an object to be inspected, and represents the appearance of a rotating means for rotating while holding the object to be inspected, and the screw of the rotating object to be inspected. The imaging device that captures an image, the calculation device that calculates the area S of the bright region included in the image, and the object to be inspected are rejected when the area S is greater than or equal to a preset threshold value S0. It is an invention of a screw inspection apparatus provided with a determination means that determines that the object to be inspected is rejected when it is determined that the object to be inspected is rejected.

  According to the screw inspection apparatus according to the present invention, an image representing the appearance of the screw is taken over the entire circumference while rotating the inspection object, so that any abnormality such as a defect is detected at any position on the screw. can do. Thereby, the reliability of a test | inspection can be improved. In addition, since it has a means to rotate the object to be inspected, the time required for the inspection can be greatly reduced as compared with the method in which the inspector rotates the object by hand while inspecting with the eyes, Workers' physical fatigue can be reduced. Further, since the inspector attaches and detaches the inspection object to / from the rotating means by hand, the apparatus can be reduced in size and cost, and can be easily used in combination with visual inspection.

  The present invention also includes a step of inspecting the appearance of a screw formed on the inspection object using the screw inspection apparatus according to the present invention, and an inspection object when it is determined that the inspection is rejected. And a step of performing visual inspection of the screw of the object to be inspected when it is determined that the screw is not rejected at the time of inspection. This is an invention of the inspection method.

  According to the screw inspection method of the present invention, the inspection object is first inspected by using a highly reliable screw inspection apparatus, so that the inspector feels excessive pressure in the visual inspection performed after that. It is possible to take charge of inspections. Thereby, compared with the conventional inspection method, mental fatigue of the inspector can be reduced. In addition, when it is determined that the inspection device has failed, the appearance of the inspected screw is visually checked, so it is always checked whether the inspection device is operating normally. be able to.

  According to the screw inspection apparatus and the screw inspection method using the same according to the present invention, it is possible to reduce physical and mental fatigue of an inspector who is in charge of inspection with a small initial investment, and includes defective products. It is possible to reliably prevent the product lot from being shipped to the market.

It is a schematic diagram which shows the example of the screw inspection apparatus which concerns on this invention. It is a schematic diagram which shows the example of the position which images the image showing the external appearance of the screw of a to-be-inspected object. It is a flowchart which shows the example of the test | inspection method of the screw which concerns on this invention.

  DESCRIPTION OF EMBODIMENTS Embodiments for carrying out the present invention will be described in detail below with reference to the drawings. The embodiment described here is only an example, and the embodiment of the present invention is not limited to the embodiment described here.

  The main inspection object of the screw inspection apparatus and the screw inspection method using the same according to the present invention is a screw-type pipe joint. The screw-type pipe joint in the present invention is, for example, a screw-type malleable cast iron pipe joint defined by Japanese Industrial Standard JIS B 2301, and is made of malleable cast iron, and has a pipe taper screw at the joint with the pipe. This refers to pipe joints that have been cut. The object to be inspected in the present invention may be a screw-type pipe joint made of a material other than malleable cast iron (for example, stainless steel, etc.). It may be a screw-type pipe fitting that conforms to the standard.

  The object to be inspected according to the present invention is not limited to a screw-in type pipe joint as long as it is a product in which a screw is formed, and may be another product. Specific examples of the “other product” here include, for example, a solid plug (plug) that can be combined with a screw-in type pipe joint, a pipe threaded at an end, or a bolt.

  1st Embodiment of this invention is a screw inspection apparatus. FIG. 1 is a schematic view showing an example of a screw inspection apparatus according to the present invention. In this embodiment, the screw inspection device (1) includes a rotating means (3) and an imaging means (4) on the upper surface of the housing (10). Moreover, the failure notification means (7) is provided on the front surface of the housing (10).

  In the present invention, the rotating means (3) refers to means for rotating the inspection object (2) while holding it. The inspection object (2) is held by the rotation means (3), for example, by providing a protrusion on a part of the rotation means (3) and fitting the end of the inspection object (2) to the protrusion. Can be realized. More specifically, a biasing means that expands in a radial direction is provided on a part of the protrusion, and the biasing means is pressed against the inner diameter surface of the end of the object to be inspected (2) fitted to the protrusion, It is good also as a structure which hold | maintains to-be-inspected object (2) with a frictional force.

  The inspection object (2) is preferably held by the rotating means (3) in such a manner that the surface of the screw of the inspection object (2) is not shielded by the rotating means (3). Thereby, when the inspection object (2) is rotated by the rotating means (3), the surface of the screw is completely exposed, so that the surface of the screw can be inspected without gaps.

  The inspected object (2) is preferably detachably held on the rotating means (3). Here, “detachable” means that the inspector holds the inspection object (2) in his / her hand and attaches it to the rotating means (2), or picks up the inspection object (2) and holds the rotating means (2). It means that it can be easily removed from 2). Thereby, a test | inspection can be rapidly implemented, replacing the to-be-inspected object (2) sequentially.

  However, the force with which the rotating means (3) holds the object to be inspected (2) must be strong enough not to drop off from the rotating means (3) while the object to be inspected (2) is rotating. At the same time, the inspection object (2) must be weakened to the extent that it can be manually removed from the rotating means (3) or less after the inspection.

  In the present invention, since the inspection object (2) is attached to and detached from the rotating means (3) by an inspector using a hand, the automatic conveyance mechanism provided in the conventional inspection apparatus disclosed in Patent Document 1 or Patent Document 2 is omitted. be able to. Accordingly, the screw inspection apparatus according to the present invention can be configured as a compact inspection apparatus having a small installation area, and is therefore suitable for use in parallel with the visual inspection work by the eyes. Further, the price of the entire inspection apparatus can be made lower than that of the conventional inspection apparatus.

  The rotation of the inspection object (2) by the rotation means (3) can be realized by rotating the rotation means (3) together with the inspection object (2) being held, for example. More specifically, the rotation means (3) may be connected to the rotation shaft of the motor, and the rotation means (3) may be rotated by starting the motor with the switch (9).

  The rotation direction of the inspection object (2) by the rotating means (3) is preferably such that the inspection object (2) rotates about the axis of the screw provided on the inspection object (2). Thereby, since the position which image | photographs the image showing the external appearance of the screw seen from the imaging means (4) mentioned later does not change, the precision of a test | inspection can be improved.

  The rotation speed of the object to be inspected (2) by the rotating means (3) must be a speed at which an image can be picked up by the image pickup means (4) described later or a speed below that. Also, if the rotational speed is extremely slow, it takes time to scan the surface of the screw without gaps, which is not preferable. Therefore, the rotation speed must be determined appropriately in consideration of the performance of the imaging means and the inspection efficiency. More specifically, when the object to be inspected (2) is a general screw-in type pipe joint, the rotation speed is preferably in the range of 50 rpm or more and 100 rpm or less.

  In the present invention, the image pickup means (4) means means for picking up an image representing the appearance of the screw of the inspection object (2). The imaging means (4) is configured so as to be able to capture an optical image representing the appearance of the screw of the rotating inspection object (2). More specifically, the image can be constituted by image data captured by, for example, a CCD camera (4a, 4b). In this case, by capturing images at a sufficiently short time interval with respect to the rotation speed of the inspection object (2), an image that appears as if the rotation of the inspection object is stationary can be obtained. This makes it possible to accurately capture the form of defects present on the surface of the screw.

  The time interval at which the imaging unit (4) captures an image can be set as appropriate in consideration of the rotational speed of the inspection object (2), the processing speed of the calculation unit (5) described later, and the like. For example, when the rotation speed of the inspection object (2) is set in the above preferable range, the time interval for capturing an image is preferably set in the range of 10 ms or more and 50 ms or less. In order to adjust the imaging time interval to a preferable range, the imaging means (4) adjusts the speed at which the appearance of the screw is scanned, or the illumination means irradiates the inspection object (2) with flashlight, and the flashlight shines. A method of adjusting the time can be employed. Moreover, you may use these methods together.

  It is preferable to capture a plurality of images of one rotating inspection object (2). Thereby, the presence or absence of a defect can be inspected without gaps on the entire surface of the screw. More specifically, for example, by performing imaging for 2 seconds at a time interval of 20 ms to capture 1000 images, an appearance inspection can be performed without overlooking defects on the entire surface of the screw.

  The image picked up by the image pickup means (4) is preferably an image viewed from a direction perpendicular to the axis of the screw of the object to be inspected (2) as exemplified in FIG. Thereby, similarly to the case of visual inspection by eyes, it is possible to observe the screw defect of the inspection object (2) from an angle at which it is easy to find.

  The imaging means (4) can include illumination means (not shown). By illuminating the screw of the inspection object (2) with the illumination means, a clear image of the screw can be taken. As the illumination means, for example, a white LED can be used.

  When the illumination unit is provided close to the CCD camera (4a, 4b), a clear image may not be obtained due to the reflected light at the central portion of the screw. In such a case, for example, as shown by the broken line part in FIG. 2, by capturing only the images of the right end and the left end of the screw image that can be seen from the imaging means (4), excluding the central part of the screw, A clear image with little influence of reflected light can be taken.

  For example, as illustrated in FIG. 1, the imaging means (4) includes a CCD camera (4a) for imaging a screw provided on an upper portion of the inspection object (2), and a lower portion of the inspection object (2). The CCD camera (4b) for imaging the screw provided on the lens and the support (4c) for fixing the CCD camera (4a, 4b) to the housing (10). Thereby, the external appearance of the screw provided in the upper and lower two places of the inspection object (2) can be efficiently inspected simultaneously. Each CCD camera (4a, 4b) can simultaneously capture images of the right end and left end portions of the screw as described above.

  In the screw inspection apparatus illustrated in FIG. 1, the imaging means (4) is configured so that it can be suitably used for appearance inspection of the external thread provided on the outer peripheral surface of the inspection object (2). The screws that can be inspected by the screw inspection apparatus according to the present invention are not limited to male screws. That is, without changing the technical idea of the present invention, the screw inspection apparatus according to the present invention is provided on the inner peripheral surface of the object to be inspected (2), so that it can be suitably used for visual inspection of screws. In this case, the image pickup means (4) may be configured to pick up an image of the female screw.

  Specifically, for example, since the imaging means (4) is provided on the inner peripheral surface of the inspection object (2), the imaging means (4) can be provided at a position and an angle so as to look into the screw portion. Alternatively, the imaging means (4) can be configured so that an image of the screw can be taken because it appears on a mirror inserted at the position of the axis of the female screw of the object to be inspected (2). Furthermore, the imaging means (2) can also be constituted by a fiberscope inserted at the position of the axis of the female thread of the inspection object (2). In any of these configurations, the imaging means (4) preferably includes an illuminating means capable of irradiating the female screw with light.

  In the present invention, the calculation means (5) means means for calculating the area S of the bright region included in the still image. Here, the “brilliant region” refers to a region where light is diffusely reflected due to the presence of a defect and appears to shine more than the surrounding region. Whether or not the light is irregularly reflected at the defect portion of the screw depends on the position where the defect exists, the size of the defect, the direction of the surface constituting the defect, the illumination and the geometric positional relationship with the imaging means (4), etc. It depends.

  In the present invention, in the above example, 1000 images are taken, and each image includes images of the right and left ends of the screw. It is highly probable that this number of images includes at least one image on which irregular reflection of light is recorded as a result of irradiating the defect portion with light from various angles. Therefore, according to the screw inspection apparatus (1) of the present invention, the presence of defects is hardly overlooked, and a highly reliable inspection can be performed.

  The calculation of the area S of the bright region included in the image is performed by binarizing the image, measuring the number of white pixels corresponding to the bright region in the binarized image, and converting it into an area. Can be performed.

  In the present invention, the determination means (6) is a means for determining that the inspection object (2) is unacceptable when the area S is greater than or equal to a preset threshold value S0. The threshold value S0 can be set with reference to the defect area of the defect limit sample. Here, the defect limit sample refers to a reference for determining that an object to be inspected (2) including a defect having an area larger than that in the visual inspection by the eyes is rejected. A defect limit sample can be prepared for each type of inspection object (2).

  When setting the threshold value S0, the area of the defect of the defect limit sample can be measured using the screw inspection apparatus (1) according to the present invention, and the value of the area can be set as the threshold value S0. Setting the threshold value S0 in this way is preferable because consistency with the appearance inspection by the eyes of the conventional inspector that has been performed using the same defect limit sample is maintained.

  The determination means (6) determines that the inspection object (2) fails if one of the areas S of the bright areas calculated by the calculation means (5) for a plurality of images is greater than or equal to S0. It is preferable to determine. Thereby, the probability of overlooking the defect included in the inspection object (2) can be made as close to zero as possible.

  The determination means (6) also rejects the inspection object (2) when the area S is greater than or equal to a preset threshold value S0 multiplied by a coefficient greater than zero and less than 1. Can be configured. By multiplying the area S0 by a coefficient less than 1, it is possible to detect a defect having an area smaller than the threshold value S0. Therefore, it is possible to adjust the inspection sensitivity by setting the coefficient to an arbitrary value.

  The calculation means (5) and determination means (6) not shown in FIG. 1 can be realized by computer software executed by a computer incorporated in or connected to the screw inspection apparatus (1). More specifically, computer hardware including a central processing unit (CPU), a memory, an interface, and the like is built in the housing (10) of the screw inspection device (1), or the screw inspection device (1) is provided. By connecting to an external computer, the image can be processed by computer software executed by these computers.

  In the present invention, the failure notifying means (7) is a means for notifying the object to be inspected (2) when the determining means (6) determines that it is rejected. More specifically, the failure notification means can be configured to issue an alarm by a method that can be recognized by the inspector with five senses, such as light of a display lamp, sound of a buzzer, and the like. For example, in the embodiment shown in FIG. 1, the failure notification means (7) is constituted by a display lamp provided on the front surface of the housing (10).

  When the failure notifying means (7) is activated, the inspector can know that a defect having an area exceeding the threshold value S0 exists in the inspection object (2) inspected by the screw inspection apparatus. Thus, the inspector can recognize the inspection object (2) as a rejected product and sort it out from other acceptable products.

  In the screw inspection apparatus (1) according to the present invention, a pass notification means (8) may be provided separately from the failure notification means (7). By operating the pass notification means (8), the inspector clearly shows that the defect (2) in the inspection object (2) could not be detected as compared to the case where the failure notification means (7) does not operate. Can be recognized. When both the failure notification means (7) and the pass notification means (8) are configured by display lamps, for example, the failure notification means (7) is displayed by a red display lamp and the pass notification means (8) is displayed by green. Each of the lamps can effectively prevent the determination result from being mistaken.

  The switch (9) is for starting the inspection of the inspection object (2) by the screw inspection device (1). By providing the switch (9) with a large area at an easily understandable position of the screw inspection device (1), the operation by the inspector can be surely and easily performed.

  Further, a reset button (not shown) can be provided separately from the switch (9) in case an unexpected situation occurs during the execution of the inspection. The safety of the inspector can be ensured by urgently stopping the rotation operation of the inspection object (2) by the rotating means (3) by operating the reset button.

  The second embodiment of the present invention is a screw inspection method. FIG. 3 is a flowchart showing an example of a screw inspection method according to the present invention. In this embodiment, the screw inspection method has three steps from first to third and one conditional branch.

  The screw inspection method proceeds to the first step (S1) immediately after the start. The first step (S1) is a step of inspecting the appearance of the screw formed on the inspection object (2) using the screw inspection apparatus (1) according to the present invention. The details of this step (S1) have already been described in the description relating to the screw inspection apparatus according to the present invention, and therefore description thereof will not be repeated here.

  One conditional branch is divided into cases depending on whether or not the inspected object (2) is determined to be rejected during the inspection performed in the first step (S1). When it is determined as unacceptable, the process proceeds to the second step (S2). When it is not determined as unacceptable, that is, when it is determined as acceptable, the process proceeds to the third step (S3).

  The second step (S2) is a step in which the appearance of the screw of the inspection object (2) is confirmed by eyes. The object to be inspected (2) to be confirmed in the second step (S2) is determined to be unacceptable by the screw inspection device (1) in the first step (S1). Defects that are larger or equal in area should be observed. In the second step (S2), the inspector visually checks whether such a defect actually exists in the screw.

  In the second step (S2), the confirmation of the appearance of the screw is different from the conventional appearance inspection, and the defect is actually detected for the specific inspection object (2) in which the presence of the defect is detected in advance by the screw inspection apparatus. This work is performed for the purpose of reconfirming that it exists. Therefore, the mental burden on the inspector is much less than that of the conventional appearance inspection.

  In general, since the number of inspected objects (2) determined to be unacceptable in the first step (S1) in the production lot is not so large, visual confirmation is performed in the second step (S2). Therefore, the physical burden on the inspector does not increase.

  The inspection object (2) in which the defect is actually confirmed in the second step (S2) can be managed so as not to be selected as a rejected product and shipped as a product. The rejected products are analyzed for defect size, occurrence position, occurrence frequency, and the like, and the results of the analysis can be used as countermeasures for reducing defects.

  If the defect cannot be visually confirmed in the second step (S2), the result of the inspection by the screw inspection device and the result of the inspection by the eye of the inspector do not match. In such a case, it is possible to investigate the cause of the discrepancy and take specific measures such as adjusting the coefficient so that the results of both inspections match.

  The third step (S3) is a step of inspecting the appearance of the screw of the inspection object (2) with the eyes. The inspection object (2) to be inspected in the third step is determined to pass in the inspection by the screw inspection apparatus (1) in the first step (S1). There should be no defects with a large or equal area. In the third step (S3), the inspector again visually inspects that such a defect is not recognized in the screw.

  In the third step (S3), the screw appearance inspection work is different from the conventional appearance inspection in that the defect is actually detected for the specific inspection object (2) in which the presence of the defect is not detected by the screw inspection device. This is an operation that is carried out for the purpose of inspecting again that it is not allowed. Since a defect that can be seen by anyone who may be included in the inspection object (2) should be detected in the first step (S1), the inspector does not feel excessive pressure. . Therefore, the mental burden is much less than conventional visual inspection.

  In a preferred embodiment of the present invention, the screw inspection apparatus (1) determines the presence or absence of defects using a plurality of images for one inspection object (2), but the screw inspection apparatus (1) is normal. Even if it operates, the possibility of determining a pass without being able to identify the defect is not zero. Even in such a case, in the screw inspection method according to the present invention, the second appearance inspection is performed again in the third step (S3) to ensure that the rejected product flows out to the market. Can be prevented.

  In addition, when the inspection object (2) having an area larger than or equal to the threshold value S0 is frequently found in the third step (S3), the screw inspection apparatus (1) operates normally. Suspected not. In such a case, it is confirmed whether or not the screw inspection device (1) is operating normally, and if an abnormality is found in the operation, it is repaired to cause a failure of the screw inspection device (1). It is possible to avoid the unexpected situation.

  In the third step (S3), the inspection object (2) in which no defect is larger than or equal to the threshold value S0 is inspected by the screw inspection apparatus (1) and the inspection by the inspector. It can be selected as an acceptable product after two inspections and shipped as a product.

  In the screw inspection method according to the present invention, the second step (S2) and the third step (S3) may be performed for each inspection object (2) or the first step (S2) may be performed. A plurality of inspection objects (2) selected in advance in step (S1) may be collectively implemented later. Since the screw inspection apparatus according to the present invention has a small installation area and can be configured compactly, the inspector moves from the first to the third steps regardless of the former method. Can be carried out at the same place without.

  In the screw inspection method according to the present invention, the visual inspection by the eyes in the second step (S2) and the visual inspection by the eyes in the third step (S3) may be performed by an inspector with the naked eye, Further, a magnifying glass or other optical equipment may be used. In this case, the inspection object (2) may be rotated by an inspector by hand as in the conventional inspection method, or the inspection object (2) may be rotated by a screw inspection apparatus ( You may rotate slowly in the state hold | maintained at the rotation means (3) of 1).

  As described above, since the screw inspection apparatus according to the present invention has a small installation area, is compact, and is inexpensive, it can be introduced into an existing production line with less economic burden than conventional inspection apparatuses. In addition, the screw inspection method according to the present invention organically combines a screw inspection device and a conventional appearance inspection to complement the appearance inspection and significantly reduce the mental and physical burden of the inspector. At the same time, the outflow of rejected products to the market can be surely prevented, so the industrial utility value is extremely high.

DESCRIPTION OF SYMBOLS 1 Screw inspection apparatus 2 Inspected object 3 Rotating means 4 Imaging means 4a CCD camera (for upper imaging)
4b CCD camera (for lower imaging)
4c support 5 calculation means 6 determination means 7 failure notification means 8 acceptance notification means 9 switch 10 housing

Claims (2)

A screw inspection device (1) for inspecting the appearance of a screw formed on an object to be inspected (2),
A rotating means (3) for rotating while holding the object to be inspected (2);
Imaging means (4) for imaging an image representing the appearance of the screw of the rotating object (2);
Calculation means (5) for calculating the area S of the bright region included in the image;
When the area S is greater than or equal to a preset threshold value S0, determination means (6) for determining that the inspection object (2) is unsuccessful;
A screw inspection device (1) comprising failure notification means (7) for notifying the inspection object (2) when it is determined that the inspection object (2) is failed. Inspecting the appearance of the screw formed on the object to be inspected (2) using the screw inspection device (1) defined in claim 1;
When it is determined that the inspection is unsuccessful, the visual inspection of the screw of the inspection object (2) is performed; and
And a step of inspecting the appearance of the screw of the object to be inspected (2) with eyes when it is not determined to be unacceptable during the inspection.