JPH0618469A - Cylindrical can body coating film defect detection device - Google Patents

Abstract

(57) [Summary] [Purpose] Improving coating quality by detecting defects in the coating on the inside and outside of the can of a cylindrical can after welding, both on the seam and on the circumference. . [Structure] Place the cylindrical can body on the rubber rolls 11 and 11,
The rotatable contact electrodes 17 and 19 are brought into contact with the open end of the can body, and the first and second electrode nozzles 52 and 54, both of which have discharge holes and suction holes formed on the electrode surfaces, sandwich the can body. They are placed close to the inner and outer surfaces. Electrolyte solution is discharged from the discharge hole of each electrode nozzle to the coating film surface, and is sucked by the suction hole. While continuously applying the electrolytic solution to the coating film surface, voltage is applied between the contact electrode and each electrode nozzle, Is horizontally moved or horizontally and rotationally moved as set in advance, and the presence or absence of each coating film defect in the joint portion and the circumferential portion is detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention has a joint portion and
For a straight cylindrical can body (coating can called eyeglass can or cylinder can) that has a coating film on both outer surfaces, distinguish at least the seam part and the entire peripheral surface (circumferential part) of the can body other than the seam part, and at least The present invention relates to an apparatus for detecting the presence or absence of coating film defects on one coating film surface.

[0002]

2. Description of the Related Art Generally, a three-piece welded can having a seam made of a material such as tin-plated steel plate or tin-free steel plate has a protective coating on the inner surface of the can body to prevent corrosion due to attack of contents. The film is applied and the outer surface is provided with a print layer for decoration and a transparent protective coating for protecting this print layer. In addition, the metal is exposed at the cut end surface of the seam formed by welding, etc., and since it becomes a source of rust if it is left as it is, a striped protective coating is applied to the inner and outer surfaces of the seam after forming the cylindrical can body. ing.

However, when a cylindrical can body is formed from a metal plate which has already been coated with coating films on both sides, scratches (scratches) on the inner and outer surfaces of the protective coating film due to contact with a molding part such as a bending roll. ) Or when welding the seam, the molten metal is likely to splash (splash) around the seam and the surrounding area. Due to the adhesion of the molten metal, a sufficient protective coating film should be applied to the seam. May occur, and a defective coating film with exposed metal may occur.

As an apparatus for detecting defects in the protective coating film, an enamel detector (for example, disclosed in Japanese Utility Model Publication No. 61-23795) which detects defects in the coating film on the inner surface of a can is generally used. ing. In addition, a coating film defect is detected for each minute section, for example, Japanese Patent Laid-Open No. 63-
A metal exposure measuring device disclosed in Japanese Patent No. 44158 is also proposed.

The former enamel lator uses a can body after a bottom lid is wound around a can body and is formed by putting an electrolytic solution such as saline or sodium sulfate aqueous solution in a cup-shaped can. Contact the electrode with the exposed metal part of the bottom or open end of the can, immerse the other electrode in the electrolytic solution, apply a voltage between both electrodes and measure the current flowing in the electrolytic solution to determine the quality of the protective coating. This is a device to be evaluated.

In the latter measuring device, measurement can be performed using a cylindrical can body before the bottom cover is wound and formed on the can body. In use, one electrode is brought into contact with the open end of the can body. On the other hand, the holding member of the measuring electrode having the electrolyte holding member at its tip is brought into pressure contact with the coating film surface. In this state, the can body and the measuring electrode are moved relative to each other, a voltage is applied between the electrodes at a constant pitch, and the current flowing between the two via the electrolytic solution can be detected separately for each minute section. It is the device

[0007]

In recent years, the coating film on the outer surface of the can body, which is not required to have high corrosion resistance as much as the inner surface of the can body, has high quality without coating defects from the viewpoint of commercial value. Is being requested. However, neither of the above-mentioned prior arts detects the coating state of the outer surface of the can body, so that the outer surface of the can body has to be visually inspected by an operator or an inspector as in the past, and it is manually operated. There is a problem that the quality of the outer surface cannot be improved because there is a limit to the inspection. Moreover, the above-mentioned prior art has the following problems.

That is, in the enamellator, the current value flowing between the can body and the electrode via the electrolytic solution is measured as a total value (if there are a plurality of defective portions, the measured values are different from those of the defective portions). The current value will be added). Also, coating film defects on the bottom lid are also measured, so if the current value is detected and evaluated as a coating film defective product, it is the can body part or the can lid part that has the defect. In that case, it is not possible to immediately determine where the defect is located and how much the defect is, which delays the handling of the flaw generation source. Further, since the defective cans can be found only in the final step in which the bottom lid is wound up, there is a problem that a large number of defective cans have already been generated when they are found in the mass production line.

On the other hand, the above-mentioned inspection device for detecting by detecting each minute segment uses the cylindrical can body which is flowing in the production line before the bottom lid is wound around the can body, and the inner surface coating film defects are detected.
Since the detection can be performed for each minute segment, it is considered that the above-described problem is temporarily solved in that the location of the defective portion and the degree of metal exposure of the defective portion can be obtained at an early stage. However, there is still a problem to be solved in order to make it possible to detect defects in the circumferential portion other than the seam portion. That is, since the can body is only moved in a certain direction with respect to the electrodes, the can body must be repositioned many times in order to detect defects in the circumferential portion other than the joint portion. However, it takes a lot of time and effort to measure coating film defects in the entire circumference of the inside and outside of the can body including the seam.

In view of these problems, the present invention uses a cylindrical can body before bottom lid winding-molding to form a coating defect on at least one coating surface of the inner and outer surfaces at a set pitch at a joint portion and a circumference. It is an object of the present invention to provide a cylindrical can body coating film defect detection device that can detect a coating film defect generation source easily by dividing into parts and parts, and can easily prevent the occurrence of defective cans.

[0011]

[Means for solving the problem] having a seam portion, and
A detection device for detecting a coating film defect on at least one coating film surface of a cylindrical can body having a coating film on both outer surfaces by distinguishing a seam portion and a circumferential portion from each other. A can rotating earth part mounted with a can rotation driving mechanism for rotating the center of the can body so as to position the joint part of the can body at a position corresponding to an electrode nozzle described later, and a contact electrode rotatable in a state of being in contact with an opening end of the can body. A linear drive mechanism for horizontally moving the can rotating earth part on which the positioned can body is placed toward the electrode nozzle, and an electrolytic solution discharge hole and an electrolytic solution suction hole which are arranged in the traveling direction of the can body. At least one electrode nozzle, which is provided on the tip surface so as to come into contact with at least one coating surface via the electrolytic solution so as to be close to and away from the coating surface, and the contact electrode. Applying a voltage between the electrode nozzle and the electric current flowing based on the coating film defects. Cylindrical Kandonurimaku defect detecting device, wherein a and a measurement mechanism for detecting and distinguishing between seam portion and the circumferential portion.

[0012]

The can barrel including the joint portion and the inner and outer surfaces of which are coated is laid horizontally on the can rotating earth portion, and the rotatable contact electrodes are brought into contact with the can barrel opening (metal exposed portion). When the can body is rotated and the seam reaches the position corresponding to the electrode nozzle, the rotation is stopped, and the can body is moved horizontally with the contact electrode in contact with the contact rotating electrode to the measuring section including the electrode nozzle. Let At the measurement position, bring the electrode nozzle close to the paint film surface of the can body joint, and forcibly discharge and adhere the electrolyte solution to the paint film surface from the discharge hole of the electrode nozzle, and overflow the electrolyte solution that has adhered to the paint film surface. Without suction, the can barrel is moved horizontally with respect to the electrode nozzle while continuing this discharge and suction, and a voltage is applied between the contact electrode and the electrode nozzle at each set pitch, Detects coating film defects in the area. Similarly, the can body is horizontally moved while rotating with respect to the electrode nozzle, and a coating film defect in the circumferential portion is detected.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A simultaneous defect detecting apparatus for inner and outer coating surfaces will be described below as a preferred embodiment of the present invention with reference to the drawings.

FIG. 1 is a front view showing the apparatus of this embodiment.
2 is a schematic plan view thereof, and FIG. 3 is a sectional view taken along line III-III of FIG.

First, the entire apparatus of this embodiment will be described with reference to FIGS. A linear drive mechanism 3 is arranged on a base 2, on which a can rotating earth part 4 which is horizontally movable as the linear drive mechanism 3 is driven is placed, and a front position where the can rotating earth part 4 moves ( On the right side of FIG. 1, the can rotating earth part 4
A measuring mechanism 5 is arranged to simultaneously inspect the coating film defects of the cylindrical can body 1 positioned at 1.

As shown in FIGS. 1 and 3, the can rotating earth portion 4 is provided with a can rotation driving mechanism 6 for rotating and positioning the can body 1 (indicated by a chain double-dashed line) that is horizontally placed about the can axis. ing. Reference numeral 11 in the drawing denotes a rubber roll for rotating the can body 1, and two rubber rolls are rotatably attached to the sidewalls of the U-shaped saddle-shaped member 12 when viewed from the front, with two spaces in parallel. The rubber roll 11 rotates in the same direction via the belt 14 and the pulley 15 by the rotation of the stepping motor 13 attached to the left side surface of the saddle-shaped member 12. Further, a long and thin magnet 16 is provided between the rubber rolls 11 and 11 and is supported so as to be vertically movable by driving a cylinder 16a. When the can body 1 rotates, the magnet 16 is close to the outer surface of the body part and attracts the can body 1 to the rubber roll 11 so that the can body 1 can rotate without slipping.

In FIG. 1, reference numerals 17 and 19 denote contact electrodes provided on both ends of the can body 1, respectively, which contact the open ends of the can body 1 to apply a voltage to the can body 1. Of these, the right contact electrode 1
Reference numeral 7 also serves as a fixed gauge for positioning the can body in the longitudinal direction, and is rotatably supported by a fixed bracket 18 made of an insulating material. On the other hand, the left contact electrode 19 is rotatably supported by a horizontally movable bracket 20 made of an insulating material. As shown in FIG. 2, a pair of these electrodes 17 and 19 are provided on both sides of the can body 1, but a contact electrode for applying a voltage to the can body may be provided at any one of these positions. , 19 are used as the application electrodes. The contact electrode 19 is provided with a terminal 19a which is in sliding contact with the contact electrode 19 and is connected to a power source for measurement described later.

Reference numeral 21 is a cylinder for horizontally moving the bracket 20 which pivotally supports the contact electrode 19, which is fixed to the L-shaped members 12b provided on both sides of the saddle-shaped member 12, and the tip of the rod is bracketed. It is connected to the lower part of 20 (see FIG. 1). Reference numeral 22 denotes a guide rod of the bracket 20, which penetrates the block 23 fixed to the upper surface of the L-shaped member 12b and extends horizontally toward the fixed bracket 18 side, and the bracket 20 is extended as the rod of the cylinder 21 extends and contracts. Move to the left and right.

On the other hand, reference numeral 24 is an ultrasonic reflection type seam detection sensor which emits ultrasonic waves toward the top surface of the can body 1 which is horizontally placed on the rubber roll 11 and detects a reflected wave at the seam portion 1a. And is attached to a bracket 24a extending upward from the L-shaped member 12b. Reference numeral 25 is a can detection sensor that is provided adjacent to the seam detection sensor 24 and that detects the presence or absence of a can body.

Next, the linear drive mechanism 3 will be described. 31
Is a horizontally long frame body provided on the base 2, and side plates 31a and 31b extend upward from both ends thereof to form side plates 31a and 3b.
The screw shaft 34 rotatably supported on the saddle member 1b
2 is screwed with an extending portion 12a extending downward. A support bar 33 is bridged on the side plate, and a slide rail 32a is fixed on the support bar 33 to guide the linear slider 32 attached to the lower surface of the saddle-shaped member 12.

The screw shaft 34 extends through the left side plate 31b of the frame 31, a pulley 37 is attached, and the tip end is connected to the drive shaft of the rotary encoder 35 by a coupling 36. In the pulley 37, a motor 38 is provided in the frame body 31, and the pulley 3 is fixed to the shaft end thereof.
9 and the belt 40. As a result, the screw shaft 34 rotates in accordance with the rotation of the motor 38, and the can rotating earth part 4 horizontally moves along the slide rail 32a.
At the same time, the rotary encoder 35 is rotated to generate a pulse signal. This is to control the movement of the can body 1 on the can rotating earth part 4 via a control mechanism (not shown) from a computer processing device to be described later, or to read the movement of the can body 1 into the computer processing device to This is because the measurement position of 1 can be discriminated.

Next, the measuring mechanism 5 will be described. As shown in FIG. 1, the measurement mechanism 5 includes a right side plate 31a of the frame body 31.
It is supported by a substantially T-shaped support plate 44 when viewed from the front mounted on the overhanging base 41 fixed to the.

Reference numeral 51 designates a can rotating earth portion 4 from the support plate 44.
It is an acrylic upper arm that extends to the side in a substantially horizontal direction,
Reference numeral 53 is a lower arm extending substantially parallel to the upper arm 51 and insertable into the can body 1 and made of the same material as the upper arm 51. The upper and lower arms 51 and 53 are attached to the support plate 44 by the shaft 5
It is rotatably mounted at 5,56.

A first electrode nozzle 52 made of stainless steel, which faces the coating film on the outer surface of the can body, is attached to the tip portion of the upper arm 51 with the electrode surface facing downward, and one lower arm 53.
A second electrode nozzle 54 made of stainless steel, which faces the inner coating film surface, is attached to the tip portion of the with the electrode surface facing upward. Conductive wires 57 and 58 extend from the electrode nozzles 52 and 54 to the support plate 44 side, and are further wired to a power supply (described later) terminal. The electrode nozzles 52 and 54 are disposed in front of the direction of travel of the can body that travels together with the can rotating earth portion.

On the other hand, the shafts 55 and 56 serving as fulcrums for the arms
Is a pair of gears 59, 60 penetrating the support member 44 at the tip.
Are stuck and engaged. Of these, the upper gear 59 is provided with a lever 61 extending upward, and cylinders 62 and 63 facing each other with the lever 61 interposed therebetween are attached to the support plate 44. These cylinders 62 and 63 are for opening and closing the upper and lower arms 51 and 53.
The lever 61 swings in accordance with the movements of 2, 63, and the gears 59, 60 rotate accordingly, causing the upper and lower arms 51, 53 to open and close about the shafts 55, 56.

The structure of the electrode nozzle will be further described with reference to FIGS. As shown in FIG. 4 (enlarged cross-sectional view taken along line IV-IV in FIG. 1), the tip electrode surface 52 a of the first electrode nozzle 52 has a cross-sectional shape that conforms to the contour shape of the outer surface of the can body. As shown in FIG. 5, which is a plan view of 52a, it has a rectangular shape. A recess 66 is formed in the center of the electrode surface 52a.
And an electrolyte solution discharge hole 67 is provided at the bottom of the recess 66. Further, an electrolyte solution suction hole 68 is provided close to the periphery of the recess 66 (in this example, the size of the electrode surface is 17 mm square, the recess 66 is 5 mm in diameter, and the electrolyte solution discharge hole 67 is
The diameter is 2.2 mm, and the suction holes 68 are 1.5 mm in diameter and are eight in number). The discharge hole 67 communicates with the electrolytic solution supply hole 69 of the upper arm 51, and the suction hole 68 communicates with the electrolytic solution discharge hole 70 of the upper arm 51.

The electrolytic solution, as shown in FIG.
1 is supplied from the fitting 71 attached to the No. 1 and is discharged from the discharge hole 67 of the first electrode nozzle 52 to the outer surface of the can body through the supply hole 69. The discharged electrolytic solution is sucked into the suction hole 68 and is discharged into the discharge hole 70. Is discharged from the joint 72 via. The discharged electrolytic solution is circulated and reused through the electrolytic solution circulating means 8 described below.

The electrolytic solution circulating means 8 comprises, in order from the electrolytic solution tank 81, a discharge pump 82, a branch portion 83 and a flow rate adjusting valve 8.
4, joint 71, electrolyte supply hole 69 of upper arm 51, first
The electrolytic solution supply path connected to the discharge hole 67 of the electrode nozzle 52 and, conversely, from the suction hole 68 of the first electrode nozzle 52, the electrolytic solution discharge hole 70 of the upper arm, the joint 72, the filter 85, and the suction pump in this order. And an electrolytic solution discharge path connected to the electrolytic solution tank 81 via 86.

Accordingly, when the discharge pump 82 is operated, the electrolytic solution flows from the tank 81 through the supply path and is discharged from the discharge hole 67 of the first electrode nozzle 52 to the outer surface of the can body, so that the electrolytic solution adheres to the coating film surface. At the same time, the electrolytic solution discharged into the minute gap formed between the first electrode nozzle 52 and the outer surface of the can body is sucked by the suction hole 68, collected in the tank 81, and circulated in the path.

The electrode nozzle 52 approaches the coating film surface of the outer surface of the can body so as to come in contact with the coating film surface through the electrolytic solution,
It also moves away.

On the other hand, the electrode surface 54a of the second electrode nozzle 54
Has a cross-sectional shape that follows the contour shape of the inner surface of the can body, and has the same structure and function as the electrode surface 52a of the first electrode nozzle 52.
An electrolytic solution circulating means (not shown) independent of the electrolytic solution circulating means 8 is provided.

In the apparatus of this embodiment, the electrolytic solution is appropriately adhered to the coating film surface of the can body 1, and the electrolytic solution is continuously discharged without overflowing around the first electrode nozzle 52. In order to allow suction, the flow rate adjusting valve 84 is used to control the discharge rate to 100 to 500 cc / min (preferably 150 to
200 cc / min) and the size of the electrode surface is 10
In the range of 20 mm, the gap between the electrode surface and the coating surface is 0.1 to 5
mm range, the moving speed of the coating film surface of the can body relative to the electrode surface 52a is 5 to 200 mm / sec, and the measurement pitch is 0.1 to
It was selected in the range of 17 mm. This structure is the same as in the case of the second electrode nozzle 54.

The electrolytic solution has a relatively low vacuum pressure (10 to 20 m).
Since the suction can be performed with mHg), a water-flow suction pump 86 that draws a part of the electrolytic solution from the branch portion 83 can be compact in terms of equipment.

Next, the electric circuit of the measuring mechanism 5 using the electrode nozzle will be described with reference to FIG. Contact electrode 1
9 is the negative electrode, the first and second electrode nozzles 52 and 54 are the positive electrodes,
It is connected to power sources V1 and V2 to form a conduction circuit separately for the inner and outer surfaces of the can body. On the other hand, a control mechanism (not shown) drives the can rotation drive mechanism 6 and the linear drive mechanism 3 based on the pulse signal from the rotary encoder 35 to move or rotate the can body 1 with respect to the electrode nozzle, and set. A voltage is applied between the contact electrode 19 and the electrode nozzles 52 and 54 for each pitch,
The value of the current flowing through each circuit is converted into current / voltage converters 91, 92,
It is read into the computer processing device 94 side via the analog-digital (A / D) conversion unit 93. Then, from the position of the seam portion 1a calculated in advance from the can body diameter and the rubber roll diameter, the computer processing device 94 performs statistical and discrimination processing to determine the average value and the maximum value separately for the inner surface and the outer surface, and the seam portion and the circumferential portion. In addition to displaying the data on the monitor screen separately, for the coating film defective product whose maximum value exceeds the standard value, the joint part,
The defective portions of the coating film are displayed on the screen by distinguishing between the circumferential portion and the inner and outer surfaces.

In the present embodiment, the discharge directions of the electrolytic solution are opposed to each other so that the inner and outer coating film surfaces are sandwiched by the first electrode nozzle and the second electrode nozzle. It is also possible to arrange such that the electrolytic solution discharge directions of both are downward, and the coating film defects on the inner and outer surfaces of the can body are simultaneously detected. It is also possible to dispose only one and detect only one of the inner surface and the outer surface.

The material of the upper and lower arms is not limited to the above-mentioned embodiment, and any material may be used as long as it has an electric insulation property.
It is also possible to use plastic materials such as polyamide, fluororesin (Teflon etc.), polycarbonate, etc., plastics containing fillers of inorganic materials such as mica and glass fibers, and organic materials such as nylon series and tetrafluoroethylene fibers. Further, the material of the electrode nozzle is only required to have conductivity, and for example, aluminum, copper, or alloy materials thereof, or their surfaces are plated (hard chrome plating, gold plating, etc.).
Treated products can also be used.

The arrangement and size of the recesses and the suction holes provided on the electrode surface are not limited to those in this example, and may be adjusted according to the size of the electrode surface.
It may be small or large. Even if you arrange the suction holes,
It should be close to the periphery of the recess so that the electrolytic solution does not overflow from the minute gap, and it may be arranged in several rows on both sides, in several areas surrounded by a square, or as an annular groove. Surround it with a sheet material such as ultra-thin (0.5 mm or less) soft rubber, nylon, Teflon, etc., and attach it so that it slightly contacts the can body, and seal the minute gap between the electrode surface and the coating surface with the sheet material. May be formed.

Furthermore, the overhanging base 41 supporting the measuring mechanism 5 may be moved up and down so as to be compatible with can bodies having different can diameters. Also, when cleaning the electrode nozzle, In order to improve the property, the support plate 44 fixed on the overhanging base 41 may be turned.

The electrolytic solution to be used may be an electrolytic solution prepared by mixing 1% saline solution and an aqueous solution of rapizole, or may be a conventionally used electrolytic solution such as potassium chloride, sodium nitrate, sodium sulfate or copper sulfate aqueous solution.

Next, the operation of the apparatus of this embodiment will be described.

First, the rubber roll 11 of the can rotating earth part 4
Place the can body 1 on top. The can body is a can detection sensor 25
When the contact electrode 19 is sensed by the contact electrode 19, the contact electrode 19 moves to the other contact electrode 17 side, the can body 1 is sandwiched between the contact electrode 17 and the contact electrode 17, and then returns to the original position. Subsequently, the magnet 16 between the rubber rolls 11 rises to near the surface of the can body 1, and the attraction force of the magnet 16 causes the magnet body 1 to move.
To the surface of the rubber roll 11. In this state, the stepping motor 13 is driven to rotate the rubber roll 11 in the same direction to rotate the can body 1. When the joint sensor 24 detects the joint portion 1a, the stepping motor 13 stops when the joint portion reaches the uppermost surface, and the magnet 16 descends.

Next, the contact electrode 19 moves again to press and fix the can body 1 against the contact electrode 17, and the magnet 16 rises. Then, the motor 38 rotates and the can rotating earth part 4
However, facing the electrode nozzles 52 and 54 which are open vertically with the can body 1 having both openings sandwiched by the contact electrodes 17 and 19 and positioned so that the joint portion 1a is at the uppermost position,
Move forward and reach the measurement start position.

Subsequently, the two electrode nozzles 52 and 54 approach each other and sandwich the joint portion 1a of the can body 1 from above and below. Then, the electrolytic solution discharge pump 82 is operated, and while the suction pump 86 is operated, the electrolytic solution is discharged from both electrode nozzles 52 and 54 (a discharge amount of 150 to 200 cc / min), and the discharged electrolytic solution is sucked. The electrolytic solution is continuously attached to the inner and outer surfaces of the joint portion 1a of the can body 1. The can rotating earth part 4 further advances by a predetermined distance, and a voltage (6v) is set at a set pitch (0.
5 mm) every 5 mm) to measure the current value flowing between the electrodes at each measurement pitch over the entire length of the joint portion 1a of the can body 1 to detect a coating film defect in the joint portion 1a.

After the detection of the joint portion 1a is completed, the stepping motor 13 and the motor 38 of the can rotating earth portion 4 are driven,
Voltage is set while moving the can body 1 while rotating it with respect to the electrode nozzle (straight direction 0.5 mm, circumferential direction 14
mm pitch), and this time, a coating film defect on the inner and outer circumferential surfaces is detected.

When detecting the circumferential portion, when the seam portion 1a crosses the electrode nozzle, the current value of the overlapping seam portion is not detected due to the pulse signal read into the computer processing device 94. . In this way, the measurement is completed by retracting to the measurement start position. After the end, the electrolytic solution discharge pump 82 is stopped, the first and second electrode nozzles 52 and 54 are opened,
The can rotating earth part 4 is retracted to the first place and is in a standby state.

The inspection result is judged to be good or bad by computer processing, the measured value is displayed on the monitor screen, and if it is judged to be bad, it is distinguished whether the defective portion is inside or outside the can body, or both, Moreover, the points are displayed separately for the joint portion and the circumferential portion. After that, the can body 1 is automatically discharged to a discharge chute by separating a good can and a bad can by a robot or the like.

In this example, both electrode nozzles 52,
Since 54 was installed in such a position as to sandwich the joint portion 1a located on the uppermost surface of the can body (FIGS. 4 and 6), the can body was positioned when the joint portion 1a came to the uppermost surface of the can body. However, the positioning of the can body is not limited to this, and if the can body 1 advances with the can rotating earth part 4 and the joint part is a position where it can be sandwiched by the electrode nozzles 52 and 54, both electrode nozzles can be positioned at any position. It may be present, and the position of the can body is determined correspondingly. When the coating surface of either the outer surface or the inner surface is to be inspected, the first electrode nozzle 52 or the second electrode nozzle 54 is installed at a place where the outer surface or the inner surface of the joint portion can be brought into contact with the electrolytic solution as a medium. It suffices to do so, and the circumferential surface of the can body is positioned so that the seam portion comes to a position corresponding to the position of the electrode nozzle.

The present embodiment has the following effects. It is possible to detect the coating film defects on the outer surface of the can body at the same time as detecting the coating film defects on the inner surface of the can body, which makes it possible to accurately grasp the coating condition on the outer surface of the can body. Using a cylindrical can body immediately after molding, it is possible to detect the presence or absence of coating film defects at each set pitch by dividing into a seam part and a circumferential part. As a means for adhering the electrolytic solution to the coating surface, the electrolytic solution was discharged onto the coating surface like a fountain, and the discharged electrolytic solution was always sucked.Therefore, rotate the can body to cross the seam. Electrolyte can be easily attached to the surface of the coating film even when moved to
The coating film defects can be detected reliably and quickly. Further, since the electrolytic solution circulation means is provided, the electrolytic solution can be reused, which is economical, and the continuous use is possible without replenishing the electrolytic solution for a long period of 1 to 2 weeks, and the inspection work can be performed. Can be rationalized.

[0049]

According to the present invention, the presence or absence of coating film defects in the protective coating film on at least one of the inside and outside of the can body is determined by using the cylindrical can body after forming the cylindrical body and before tightening the bottom lid. Since the inspection can be performed separately for the joint portion and the circumferential portion, and the degree of the coating film defect can be immediately discriminated for each set pitch, the cause of the scratch generation source can be investigated at an early stage and the countermeasure can be easily taken.

Further, since the electrode nozzle has an electrolyte solution discharge hole and a suction hole so that the electrolyte solution is discharged and adhered to the coating film surface, and the discharged electrolyte solution is always sucked, Can be stably and easily adhered to the surface of the coating film to ensure the detection of coating film defects.

Further, since the coating film defect on the outer surface of the can body, which has conventionally been obliged to be visually inspected by an inspector, can be detected mechanically, the quality of the outer coating film can be improved.

[Brief description of drawings]

FIG. 1 is a front view of a detection device according to an embodiment of the present invention.

FIG. 2 is a schematic plan view of FIG.

FIG. 3 is a sectional view taken along line III-III in FIG.

FIG. 4 is an enlarged sectional view taken along line IV-IV in FIG.

5 is a partial plan view taken along line VV of FIG.

FIG. 6 is an explanatory diagram showing an electrolytic solution circulation path.

FIG. 7 is a schematic diagram showing an electric circuit of a measuring mechanism.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 can barrel 1a joint part 3 linear drive mechanism 4 can rotating earth part 5 measuring mechanism 6 can rotating drive mechanism 8 electrolytic solution circulating means 11 rubber roll 13 stepping motor 17, 19 contact electrode 24 joint detection sensor 51 upper arm 52 first electrode nozzle 53 Lower Arm 54 Second Electrode Nozzle 67 Discharge Hole 68 Suction Hole 69 Electrolyte Supply Hole 70 Electrolyte Discharge Hole 94 Computer Processing Device

Claims (4)

[Claims] 1. A detection device for detecting a coating film defect on at least one coating film surface of a cylindrical can body having a seam portion and having coating films on both inner and outer surfaces by distinguishing between the seam portion and the circumferential portion. The horizontal rotation of the can body is made to rotate about the can axis, and the joint part of the can body is positioned at a position corresponding to the electrode nozzle, which is described later, in contact with the can rotation drive mechanism and the open end of the can body. A can rotating earth part on which a rotatable contact electrode is mounted, a linear driving mechanism for horizontally moving the can rotating earth part on which a positioned can body is mounted, toward the electrode nozzle, and a driving mechanism arranged in the traveling direction of the can body. Is provided with an electrolyte solution discharge hole and an electrolyte solution suction hole on the tip surface, and is provided so as to be able to approach and separate from the coating film surface so as to come into contact with at least one coating film surface via the electrolytic solution. At least one electrode nozzle, and a voltage is applied between the contact electrode and the electrode nozzle. And, cylindrical Kandonurimaku defect detecting device characterized by comprising a measuring mechanism to detect the current flowing based on the coating defect sites distinguishing between seam portion and the circumferential portion. 2. The first electrode nozzle facing the coating film surface on the inner surface of the can body, and the second electrode nozzle facing the coating surface on the outer surface of the can body are provided to detect coating film defects simultaneously on the inner and outer surfaces. Cylindrical can body coating film defect detection device. 3. The cylindrical can body coating film defect detection device according to claim 1, wherein the electrode surface of the electrode nozzle has a cross-sectional shape that follows the contour shape of the can body cross section. 4. The cylindrical can body coating film defect detection device according to claim 1, further comprising an electrolytic solution circulating means for supplying the electrolytic solution to the discharge hole of the electrode nozzle and sucking the electrolytic solution from the suction hole.