JPH052245B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a screw inspection device that performs various inspections while conveying screws.

[Conventional technology]

Conventional screw inspection equipment extracts an appropriate number of screws before carrying out a 100% inspection, measures each part of these screws, and aggregates the individual data to distinguish between good and defective items. We are trying to obtain baseline data.

For example, a worker passes non-defective products one by one through an inspection device, reads the data output from the inspection device individually, and aggregates the data to determine the average value of non-defective products.
After calculating the + tolerance and - tolerance, which are the allowable ranges of acceptable products, based on the variance or standard deviation,
I am trying to input it into the inspection device.

[Problems to be solved by the invention] However, in the above-mentioned conventional apparatus, as the number of inspection items increases, the amount of data to be handled becomes enormous, and it is necessary to calculate the judgment reference value for each inspection item and input the calculation results into the apparatus. It takes an extremely long time. For this reason, it took too much time to set up the work to be performed before the inspection, making it impossible to perform the work efficiently. Further, in the conventional screw inspection device, when the optical measuring section is provided near the conveyance end of the conveying means, the screw tends to sing as it passes through the measuring section, which may impede the inspection. Further, when sorting the screws after inspection into good and defective items, the screws were sometimes scattered below the end of the conveyance.

[Means for solving problems]

The thread inspection device of the present invention includes a transport mechanism, a measuring section, and a control means. The above transport mechanism is
The screws to be inspected are transported from the start end of the transport to the end of the transport with the screws to be inspected facing upward and the lower part of the neck suspended. It is equipped with a pair of belts that are sequentially conveyed toward each other. The conveying end of this belt is
The angle θ formed by the downwardly turned surface of the belt that has passed around a horizontal small pulley with a pulley diameter within three times the shaft diameter of the lower part of the screw neck and that has passed through this small pulley and the above conveying surface. The angle is an acute angle of less than 90°.

The measuring section is an optical measuring section provided immediately before the conveyance end of the belt, and equipped with an imaging means for taking in information regarding each part of the screw necessary for inspecting the screw. For example, an image sensor camera, a light source, a plating sensor, etc. are arranged in this measurement section. Further, a sorting mechanism is provided for sorting the screws falling from the conveyance end portion of the belt into non-defective products and defective products according to the inspection results in the measuring section.

The control means utilizes a microcomputer or the like, and while a predetermined number of screws arbitrarily determined in advance are conveyed sequentially by the belt, these screws are measured based on information about each part of the screw inputted by the measuring section. Detects data such as average value, maximum value, minimum value, variation, and other characteristic values of threads. After setting a certain judgment standard value based on the above data, the screw detected by the measuring section while being conveyed by the belt is compared with the judgment standard value. It is determined whether the product is a good product or a defective product.

[Effect]

The screw to be inspected is conveyed to the measuring section on the belt, and is dropped and discharged from the conveyance end of the belt. In the present invention, before carrying out a complete inspection of the screws, a predetermined number of screws arbitrarily determined in advance are sequentially conveyed to the measuring section by the belt, and information regarding each part of the screw is collected for each screw, for example, under the head. Incorporate information such as the length, head height, shaft diameter, number of threads, total length of the screw, tip shape, presence or absence of plating, etc. At this time, if a foreign item is mixed in, the data for the foreign item will be extremely different from the data for other screws, so screws with extremely variable data are judged to be foreign and are not adopted as data.

Based on the data for each item of the predetermined number of screws input in this way, the average value of these screws,
The maximum value, minimum value, dispersion (dispersion, standard deviation), etc. are detected by the control means, and a judgment reference value is set based on this data. After completing the above work setup, inspect the screws. In other words, when a screw is carried on a belt to a measuring section, information about each part of the screw is inputted in this measuring section, and compared with the above-mentioned criterion value, it is determined that the screw is a passed product (good product). It is determined whether or not.

The screws thus inspected are sorted into good and defective by a sorting plate or the like, depending on the inspection results, when they are discharged from the conveyance terminal end of the belt. For this reason, the measuring section is provided just before the end of conveyance, but in the present invention, the end of conveyance of the belt is wrapped around a small pulley with an outer diameter of several mm, so it In other words, the posture of the screw passing through the measurement section can be stabilized more fully than with conventional screw inspection devices, making it possible to collect accurate information on each part of the screw in the measurement section. . Therefore, it is possible to accurately obtain data on which the above-mentioned judgment reference value is based, that is, measurement data of a predetermined number of screws performed prior to inspection. At the end of the conveyance, the angle θ between the downwardly turned surface of the belt that has passed through the small pulley and the horizontal conveyance surface is an acute angle of less than 90°, so the screws falling from the end of the conveyance are concentrated in a narrow range. It passes through the sorting mechanism as it falls.

For the above reasons, even if there are many inspection items,
No human effort is required to aggregate, calculate, or input judgment reference values for each inspection item, and work setups can be completed in an extremely short time compared to conventional methods, and screw inspection can be performed at high speed.

〔Example〕

In the screw inspection system 10 shown in FIG. 1, a sorting device 12 is provided downstream of a vibrating parts feeder 11 that accommodates a large number of screws A to be inspected. This sorting device 12 includes two rotating bodies 13 and 14 that are arranged parallel to each other with a small gap between them. This sorting device 12
is to select the outer diameter (head diameter) of the head _A1 of the screw A.

The rotating bodies 13 and 14 have their conveying downstream sides lower than their conveying upstream sides.
While rotating the upper surface sides in opposite directions,
The screw A is transferred to the downstream side. A sorting part 16 with a small outer diameter is formed in a part of the rotary bodies 13 and 14, and only screws A having a predetermined head diameter fall from this sorting part 16 onto a chute 17 and are placed in an alignment device 19. sent to. Furthermore, screws with small head diameters that have fallen before the sorting section 16 are collected into a box 21 via a chute 20.
A chute 23 is also provided at the transport end side of the sorting section 16, and screws with large head diameters that have not fallen in the sorting section 16 are collected through this chute 23 into a box 24.

The alignment device 19 includes a pair of conical rotating bodies 26,
It has 27. The rotating bodies 26 and 27 are driven so that their upper surfaces rotate in opposite directions. Then, the screw A is conveyed with the head A ₁ facing upward and the lower neck portion A ₂ hanging down, and delivered from the pointed conveyance end 28 to the screw inspection device 30 in the above-mentioned posture.

The thread inspection device 30 includes a transport mechanism 31, a measuring section 32, and a control means (not shown) using a computer.

As shown in FIGS. 2 and 3, the conveyance mechanism 31 includes a pair of belts 33 stretched parallel to each other. Each belt 33 is the same, and as shown in FIG. 3 as a representative, a driving pulley 35 and a driven pulley 3
6, and a pulley 37 located at the end of the conveyance. The tension pulley 38 absorbs the elongation of the belt 33 and
Apply appropriate tension to.

The driving pulley 35 is rotationally driven in a fixed direction by a motor 40. The gap d between the belts 33, 33 is adjusted to be slightly larger than the outer diameter of the lower neck portion _A2 of the screw A. Both belts 33 are made to run endlessly in the same direction at the same speed. Therefore, screw A has its head A ₁
is hooked on the belt 33 and conveyed toward the conveyance end portion 33a with the lower neck portion _A2 hanging down. The conveyance surface 33b of each belt, that is, the pulleys 36, 3
The area between 7 and 7 is almost horizontal. In addition, the conveyance surface 3
A horizontal guide 41 supporting the belt 33 is provided on the lower surface side of each of the belts 3b to prevent the belt 33 from being bent due to the weight of the screw A.

As illustrated in FIGS. 4 and 5, the pulley 37 located at the conveyance terminal end 33a has a small outer diameter D of approximately several mm (approximately 4 to 6 mm), and is press-fitted into the bearing 43. It is rotatably supported by a pin 44. Therefore, the conveying end 33 of the belt
a has a fairly sharp curved shape. The material of the belt 33 may be, for example, a polymeric material such as synthetic rubber, but a material with excellent flexibility is used so that it can sufficiently adapt to the small radius of curvature of the pulley 37.

Further, as shown in FIG. 4, the angle θ formed by the conveyance surface 33b of the belt toward the pulley 37 and the downwardly turned surface 33c of the belt that has passed the pulley 37 at the conveyance end portion 33a of the belt is an acute angle (θ <
90°). In the illustrated example, θ=about 70°, but it may be within the range of 60°<θ<90°. In other words, if the angle of the above-mentioned return surface 33c with respect to the vertical plane is θ ₀ , then 0<θ ₀ <30°.

The measuring section 32 is provided immediately before the transport end section 33a. The optical measurement section 32 includes, for example, a plating sensor 46, an image sensor camera 47 as an example of an imaging means, an optical fiber device 48, and the like. The plating sensor 46 determines whether the plating is good or bad based on the light reflected from the screw A. The image sensor camera 47 collects information about each part of the screw, such as the length under the neck, the height of the head, the shaft diameter,
Incorporate information regarding the number of threads, total length of the screw, tip shape, etc. The optical fiber device 48 is provided at a position facing the image sensor camera 47 and is used as a surface light source.

The information on each part of the screw taken in by the measuring section 32 is input to the control means using a computer. In this control means, by comparing information regarding the screw A taken in by the measuring section 32 with judgment reference values described later for each inspection item, it can be determined whether the screw A that has passed through the measuring section 32 is a good product or a defective product. They are programmed to make decisions.

A sorting mechanism 50 is located near the conveyance end portion 33a.
is provided. This sorting mechanism 50 is equipped with a sorting plate 52 driven by an actuator 51 whose drive source is a rotary solenoid or pulse motor, etc. Acceptable products that have passed the inspection items are sent to a good product collection box via one chute 53. Defective products that do not pass the inspection items are stored in a defective product collection box 56 via the other chute 55.

Next, the operation of the screw inspection device 30 having the above configuration will be explained. In this embodiment, before carrying out a complete inspection of the screws A, the number of screws A arbitrarily determined by the user (for example, about several hundred pieces) is transferred to the transport mechanism 31.
The screws are conveyed one after another to the measuring section 32, and information regarding the inspection items for each part of each screw, such as length under the neck, height of the head, shaft diameter, number of threads, total length of the screw, etc.
Incorporate information indicating the tip shape, presence or absence of plating, etc. When you have finished entering the specified number of items,
The transport mechanism 31 is stopped. Since the predetermined number of screws sampled in this way are randomly selected from a large number of lots to be inspected, there is a possibility that foreign items may be mixed in in rare cases.
However, since the data for the foreign product is clearly different from the data for the majority of other screws, screws with extremely variable data can easily be determined as foreign. Data on screws that are determined to be foreign items will not be accepted.

After inputting the data of a predetermined number of screws A in this way, the average value, maximum value, minimum value, dispersion (dispersion, standard deviation), etc. of these screws A are calculated by the control means, and the results are displayed on the display. etc. will be displayed. If any of the screws A has a minimum or maximum data value that exceeds the ± tolerance required by the user, a message is output to alert the user. Then, based on the above data, the half-cut reference value, which is the standard for determining the quality of the screw, that is, the average data of good products for each inspection item, + tolerance, - tolerance, etc. is automatically determined by the above control means. It is made according to the method. The data created in this way may be used as it is as a criterion for determining good and defective products, but of course it is also possible to make corrections such as narrowing or widening the criteria for passing/failing based on the above data. No problem. The flow of the above series of processes is shown in FIG.

As mentioned above, the screws sampled and measured prior to the inspection may contain screws that do not meet the acceptance criteria, so they are first collected in the defective product collection box 56 and then returned to the lot that will be inspected from now on. I'll keep it.

After completing the above work setup, all screws A are inspected. That is, the screw A to be inspected
is carried on a belt 33 to a measuring section 32, and information regarding each part of the screw is inputted at the measuring section 32. Then, by comparing the data for each screw with the above-mentioned determination reference value, it is determined whether this screw A is an acceptable product (non-defective product).

The screws A thus inspected are sorted by the sorting plate 52 from the non-defective product collection box 54 to the defective product collection box 56 according to the test results when being discharged from the transport end portion 33a.

For this reason, the measuring section 32 is provided just before the conveyance end section 33a, but in this embodiment, the conveyance end section 33a of the belt is wound around a small pulley 37 with an outer diameter of several mm, so The posture of the screw A can be kept stable until it is about to fall. In other words, the measuring section 32
Even though the screw A is quite close to the measuring part 32
A predetermined posture can be maintained until the object has completely passed through, and inspection can be performed with high precision.
According to the research conducted by the present inventors, as illustrated in FIG. 7, when the outer diameter of the pulley 37 is considerably larger than the head diameter of the screw, the posture of the screw A collapses before it finishes passing through the measuring section. It was found that this adversely affected measurements, causing non-defective products to be judged as defective. However, in this embodiment, as described above, by making the outer diameter D of the pulley 37 sufficiently small to 4 to 6 mm, the shaft diameter of the lower neck portion _A2 is 2 to 6 mm.
It has become possible to extremely accurately measure screws A whose length under the neck is approximately 6 mm and the length under the neck is approximately 6 times the pulley diameter D (for example, the length under the neck = around 40 mm). Therefore, it is possible to collect accurate information on each part of the screw in the measurement unit 32, and it is possible to accurately obtain data that is the basis of the above-mentioned judgment reference value, that is, measurement data for a predetermined number of screws performed prior to 100% inspection. Not only can the screws be inspected accurately after the setup is completed, but also measurements can be made accurately. Note that if the diameter of the pulley 37 is smaller than the above value (4 to 6 mm), the shaft diameter of the pin 44 will become too thin, resulting in unreasonable strength, and the radius of curvature of the belt 33 will become too small to be practical. I can't do it. Also,
If the diameter of the pulley 37 exceeds the above value, the posture of the screw immediately before ejection becomes unstable, causing a good product to be judged as a defective product.

As explained above, according to the screw inspection device 30 of the present embodiment, even if there are a large number of inspection items, no human labor is required for calculating or inputting the judgment reference value according to each inspection item, and compared to the conventional method, Work setups can be completed in an extremely short time, and screw inspection can be performed at high speed and with high accuracy.

In addition, at the conveyance end portion 33a, a pulley 37
By making the angle θ between the conveying surface 33b of the belt toward
It has become possible to concentrate the screws A falling from the ground in a relatively narrow area. If the above θ is 90° or more than 90°, the screw will
When the screws are ejected (dropped) from 3a, the screws tend to be scattered over a wide range at the point where they fall, and there is a large degree of dispersion in the falling position.

〔Effect of the invention〕

According to the present invention, even if there are many inspection items for screws,
The effort and time required for work setup can be significantly reduced, and screw inspection can be performed at high speed. Furthermore, since the posture of the screw near the end of conveyance becomes stable, the measuring section can be placed very close to the end of conveyance. Therefore, the screws after inspection can be quickly sent to the sorting mechanism, and the timing of sorting can be determined easily. Since the large number of screws that fall from the conveyance end of the belt after inspection can be concentrated in a relatively narrow area, the screws are not scattered, and the screws can be easily handled by the sorting mechanism.

[Brief explanation of the drawing]

1 to 6 show an embodiment of the present invention, FIG. 1 is a perspective view of a screw inspection system equipped with a screw inspection device, FIG. 2 is a plan view of a part of the conveyance mechanism, and FIG. 3 4 is a side view of a part of the conveyance mechanism, FIG. 4 is a schematic side view of the belt, FIG. 5 is a longitudinal sectional front view showing the conveyance end of the belt, and FIG. 6 is a diagram showing the flow of data processing in work setup. be. FIG. 7 is a side view illustrating a case where the diameter of the pulley is large at the end of the conveyance. A...screw, _A1 ...head, _A2 ...lower part of neck, 30...
Screw inspection device, 31...transport mechanism, 32...measuring unit,
33... Belt, 33a... Conveyance end portion, 7... Pulley.

Claims (1)

[Scope of Claims] 1. The screw to be inspected is conveyed with the screw to be inspected in a posture in which the screw to be inspected is suspended with the lower part of the neck thereof suspended, with conveying surfaces extending parallel to each other in the same horizontal plane so as to be substantially horizontal. A pair of belts are provided that sequentially convey from the start end to the end of the conveyance, and the conveyance end of the belt is wound around a small horizontal pulley having a pulley diameter within three times the shaft diameter of the lower neck portion of the screw. A conveyance mechanism in which the angle θ between the downwardly turned surface of the belt that has passed through the small pulley and the conveyance surface is less than 90 degrees, and a conveyor mechanism that is installed near the conveyance end of the belt and is necessary for inspecting screws. an optical measurement section equipped with an imaging means that captures information about each part of the screw, and a predetermined number of screws that are sequentially conveyed by the belt and are measured based on the information about each part of the screw inputted by the measurement section. After detecting data such as the average value, maximum value, minimum value, variation, and other characteristic values of the thread, and setting a judgment standard value based on this data, the thread is then transported by the belt. a control means for determining whether the screw detected by the measuring section is a good product or a defective product by comparing the screw detected by the measuring section with the judgment reference value; A screw inspection device characterized in that it is equipped with a sorting mechanism that sorts the products into good and defective products according to the inspection results.