JP2518128B2 - Defect inspection device for inner coating of metal can - Google Patents

Description

Detailed Description of the Invention

[0001]

The present invention relates to an inner surface organic material of a seamless metal can having an organic coating layer such as a plastic film film or a coating film on the inner surface, which is used for canning beer cans, carbonated beverage cans, coffee beverage cans and the like. The present invention relates to a film layer defect inspection apparatus.

[0002]

2. Description of the Related Art The specification relating to Japanese Utility Model Application Laid-Open No. 2-59109 (Japanese Patent Application No. 1-55451) discloses a case in which an organic coating layer is formed on both surfaces, for example, a thickness of 30 on a surface to be an inner surface of a can.
A polyethylene terephthalate film having a thickness of μm, a metal plate having a polyethylene terephthalate film having a thickness of 20 μm adhered to the outer surface of the can, for example, a blank of tin-free steel (thickness is, for example, 0.13 mm) is drawn and reprocessed. Described is a seamless metal can having an inner and outer surface coated with an organic coating layer, which is formed by drawing, bottom doming, neck-in, and flange processing.

The inner surface organic coating layer of this type of seamless metal can may cause defects such as scratches and local peeling portions in the above-mentioned processing steps. Defects are particularly likely to occur in the inner surface organic coating layer of the neck-in portion or the annular protruding portion at the bottom. These defects are not preferable because they corrode the metal due to the contents, leading to elution of metal ions into the contents and perforation of the metal layer.

As a defect inspection method for the inner surface organic coating layer, conventionally, mainly an enamellator has been used.
The Later method is used (for example, "Handbook of Packaging Technology", page 1845, July 20, 1983, Nikkan Kogyo Shimbun). This is an electrolytic solution (for example, 1% NaCl aqueous solution) with the metal plate side having the organic coating layer serving as the positive electrode.
This is a method in which a constant voltage (usually 6 V) is applied between the electrode (negative electrode) immersed therein, and the flowing electrolytic current is measured. This electrolytic current is said to be substantially proportional to the metal exposed area.

In this enamellator method, since the inspection object is contaminated by the electrolytic solution, even if the inspection value is normal, it is difficult to pass it to the subsequent production process, and the inspection of the inspection object is performed. There is also a problem that it takes time and labor to attach the device to the device in order to prevent electrolyte leakage. Therefore, the enamellator method has been conventionally used only for sampling inspection. Therefore, a defective product may be mixed in the product.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a defect inspection device for an inner surface organic coating layer of a seamless metal can, which can automatically perform 100% inspection at high speed.

[0007]

A defect inspection apparatus for an inner surface organic coating layer of a seamless metal can having at least an inner surface coated with an organic coating layer according to the present invention includes a plurality of spindles to which a holder for a conductive brush is fixed. Turret disk axially mounted along the peripheral edge; sun gear that is fixed to the frame that supports the turret disk, meshes with the gear installed on the spindle, and rotates the spindle as the turret disk rotates; seamless A means for externally mounting the metal can on the conductive brush; an electrode piece capable of contacting the end face of the opening of the seamless metal can in which the conductive brush is inserted; a DC power supply for applying a high DC voltage between the conductive brush and the electrode piece; At least during the period when the seamless metal can is extrapolated to the conductive brush and during the period when the seamless metal can is separated from the conductive brush, the conductive brush is contracted, and at least between the conductive brush and the electrode piece. Means for expanding the conductive brush during the period when a high voltage DC voltage is applied to it; and an electric circuit for detecting a pulse wave generated by a discharge based on the applied high voltage DC voltage when the organic coating layer has a defect It is characterized by

[0008]

In the device of the present invention, a plurality of spindles to which the holding body of the conductive brush is fixed, a turret plate axially mounted along the peripheral edge, and a frame supporting the turret plate are fixed to the spindle. Since the sun gear that meshes with the provided gear and rotates the spindle with the rotation of the turret board is provided, the spindle can automatically rotate with the revolution of the spindle. Further, the metal can is equipped with a means for extrapolating the metal can to the conductive brush, and a means for contracting the conductive brush at least during the period when the metal can is extrapolated to the conductive brush and during the period when the metal can is detached from the conductive brush. Even in the case of the neck-in can, the conductive brush can be automatically and easily inserted into the metal can.

An electrode piece capable of contacting the end face of the opening of the metal can in which the conductive brush is inserted, a DC power source for applying a high voltage DC voltage between the conductive brush and the electrode piece, and a high voltage between at least the conductive brush and the electrode piece. The period during which the DC voltage is applied,
The inner surface organic film is provided with a means for expanding the conductive brush and an electric circuit for detecting a pulse wave generated by a discharge based on the applied high voltage DC voltage when the organic film layer has a defect. Defects such as layer scratches or localized delamination can be detected automatically.
Since the detection time by the electric circuit is extremely short, it is possible to perform 100% inspection at high speed by increasing the number of spindles arranged on the turret board and increasing the rotation speed of the turret board.

[0010]

EXAMPLES In FIG. 1, 1a and 1b are conductive brush holders, and 2 is a metal spindle capable of rotating and reciprocating in the axial direction. The conductive brush holders 1a and 1b are fixed to the slides 5a and 5b, respectively. The slides 5a and 5b are slidably attached along pins 4a and 4b which are fixed to the tip end of a sleeve 15 (FIG. 6) which surrounds the spindle 2 and which is horizontally mounted on a cylindrical body 3 at a fixed position in the axial direction. (Fig. 5).

At the front end of the spindle 2, a projecting piece 7 having a relatively thin tip portion 7a and a relatively thick base portion 7b.
Is stuck. Rolls 6a and 6b are attached to the rear sides of the slides 5a and 5b, respectively. The roll 6a is arranged above the projecting piece 7, and the roll 6b is arranged below the projecting piece 7.

When the spindle 2 is at the forward position, as shown in FIG. 7, the base portion 7b enters between the rolls 6a and 6b, and the gap width between the rolls 6a and 6b increases,
Therefore, the distance between the slides 5a and 5b becomes smaller, and the conductive brush 10 contracts. When the spindle 2 is in the retracted position, as shown in FIG.
6b, the gap width between the rolls 6a and 6b becomes smaller (FIG. 2), and the action of the spring 8 (FIG. 5) causes the slides 5a and 5b to abut on the locking pins 9a and 9b, respectively. And the conductive brush 10 expands.

Each of the conductive brush holders 1 a and 1 b has a conductive brush piece 1 of the body part of the metal can 11.
0a and 10b are fixed so as to extend in the axial direction and the radial direction facing each other (FIGS. 1 and 3). Further, a conductive brush piece 10c for sweeping the bottom of the metal can 11 is fixed to the conductive brush holder 1a. The conductive brush 10 is composed of the brush pieces 10a, 10b, and 10c.

Each of the brush pieces 10a, 10b, 10c includes a large number of relatively soft brush filaments 12 made of conductive short fibers composed of nylon fibers (having a diameter of 0.15 mm, for example) and a nylon-carbon composite agent coating. , A holder 13 made of a metal plate piece having a u-shaped cross section for caulking the inner end portion of the brush thread 12 (FIGS. 1 and 4).
The brush element 12 has a holder 13 having a thickness of, for example, about 3 mm.
Has been densely planted. As for the length of the brush element 12, the conductive brush pieces 10a, 10b and 10c respectively have
When the conductive brush 10 is expanded and rotated, it contacts the entire inner surface (excluding the flange portion) and the entire inner surface of the bottom portion of the body portion 11b of the metal can 11 (FIGS. 1 and 4), and the tip portion thereof is It is designed to bend slightly. In the inner surface of the lower end portion 11b ₁ of the body of FIG. 1 near the grounded portion, the solid line shows the state when the conductive brush 10 is stopped, and the dotted line shows the state of the brush 10 when the conductive brush 10 is rotating. Show changes. Note that, in FIGS. 1 and 7, only a part of the brush raw yarn 12 is shown.

The metal can 11 is provided on the inner and outer surfaces of a metal plate such as tin-free steel (thickness is 0.13 mm, for example).
For example, a blank formed with an organic coating layer such as a polyethylene terephthalate film having a thickness of about 20 to 30 μm is formed by drawing-redrawing-bottom doming-body outer surface printing, drying-neck-in, and flange processing. In principle, the entire surface is covered with an electrically insulating organic coating layer except that the metal is exposed on the end surface 11a (FIG. 1) of the flange portion.

As shown in FIG. 6, the spindle 2 is
The sleeve 15 is inserted through the ball bearing 16 and the bushing 17, and the sleeve 15 can move in the axial direction but cannot rotate. The sleeve 15 includes a plurality of (for example, 18) pockets 19a provided along the peripheral edge of the first turret plate 19 fixed to the main shaft 20 (see FIG. 11) via a ball bearing 18.
Has been installed. The main shaft 20 is rotated at a predetermined speed by a driving device (not shown). The main parts of the ball bearing 18 and the turret plate 19 are electrically insulated by an electrical insulator, for example, a thin cylindrical body 19b made of MC nylon. On the rear portion of the spindle 2, a tooth portion 21a is attached with an electric insulator, for example, a gear 21 made of MC nylon.
The gear 21 meshes with a sun gear 22 fixed to a frame 23 (see FIG. 11). Therefore, as the turret board 19 rotates (the rotation speed is, for example, 83 rpm), the spindle 2 rotates about the same time as the revolution. Therefore, the conductive brush 10 is constantly rotating (for example, 6
00r. p. m. so).

At the rear end of the spindle 2, Mc nylon
A cam follower 25 is attached via a ball bearing 24 electrically insulated by the sleeve 24a. Cam follower 25
Engages with a peripheral cam groove 26 provided in the frame 23. The profile of the circumferential cam groove 26 is the turret board 19
The spindle 2 reciprocates in the axial direction at a predetermined timing with the rotation.

At the front part of the sleeve 15, the slip ring 25 and the brush 2 that contacts the slip ring 25
6 is installed (FIG. 6). The conductive brush 10 has conductive brush holders 1a, 1b, slides 5a, 5b, pins 4a, 4b, a cylinder 3, a sleeve 15, a slip ring 25, a brush 26 and a guide hole (not shown) in the main shaft 20. It is connected to the negative electrode of a high-voltage DC power supply 61 (FIG. 12; voltage is, for example, 800 to 1000 volts) via a conducting wire 27 passing therethrough and a slip ring and a brush (neither shown) attached to the rear end of the main shaft 20. .

A ring-shaped body 28 is attached to a second turret board 29 fixed to the main shaft 20 so as to surround the vicinity of the bases of the conductive brush holders 1a and 1b (FIGS. 1 and 8). The inner diameter of the front plate 28a of the ring-shaped body 28, that is, the diameter of the inner surface 28a1 is set to a size such that the body portion 11b of the metal can 11 is loosely inserted.

Between the front plate 28 a and the rear plate 28 b, a plurality (three in FIG. 8) of electrode pieces 30 are arranged at equal intervals in the circumferential direction.
(Made of stainless steel, for example) is swingably provided around the pin 31. Front side inner surface 30a of the electrode piece 30
Has a truncated cone shape that opens toward the front surface, and the rear inner surface 30b has a short cylindrical shape. The protrusion 3 is provided on the rear surface of the electrode piece 30.
0c is formed, and the protrusion 30c engages with the bottom surface of the recess 28b1 formed on the inner surface of the rear plate 28b under the pressure of the spring 32 when the metal can 11 is not inserted. The inner diameter of the rear inner surface 30b in this state is set to be slightly smaller than the diameter of the flange end surface 11a of the metal can 11. The electrode piece 30 is the ring-shaped body 2.
8, the terminal 33, and the guide hole in the main shaft 20,
A high voltage DC power supply 6 is provided via a conductor 34 connected to a slip ring (not shown) attached to the rear end of the main shaft 20.
1 to the grounded positive electrode (Fig. 12).

The can holder 35 shown in FIGS. 9 and 10 includes a bottom holder 36 that holds the bottom 11 c of the metal can 11 by vacuum suction and a body holder 37 that holds the body 11 b.
It has. A vacuum suction hole 38 is formed in the bottom holder 36, and the vacuum suction hole 38 passes through a vacuum pipe 39, a turret disk 29, a guide hole in the main shaft 20 and a vacuum valve device (neither is shown), and a vacuum source. (Not shown). The vacuum valve device has a sliding surface that comes into contact with the front end surface of the main shaft 20, and is fixed to the frame 23,
It is configured to open and close the vacuum at a predetermined timing.

The bottom holder 36 and the body holder 37
Are fixed to a common substrate 40, two sliding members 41 are fixed to the lower portion of the substrate 40, and a driving tool 43 is fixed to the upper portion. A cam follower (not shown) is attached to the right end (viewed from FIG. 9) of the drive tool 43, and the cam follower engages with a circumferential cam groove (not shown) provided in the frame 23. are doing. The profile of the circumferential cam groove is shown by the solid line in FIG. 9 at a predetermined timing of the can holder 35 holding the metal can 11 via the cam follower, and hence the drive tool 43, as the turret board 29 rotates. Position R on the right side
It is configured to reciprocate between a position L on the left side indicated by the alternate long and short dash line. At position L, the metal can 11 is shown in FIG.
The end surface 11a and the bottom portion 11c are in contact with the electrode piece 30 and the conductive brush piece 10c, respectively.

Next, a method of inspecting the inner surface organic coating of the metal can 11 for defects by using the above apparatus will be described. FIG.
As shown in 1, fed in the direction of the arrow X by feeds turret 45, turret 45 and turret 19, 29
The metal can 11 having reached the station A where it contacts is placed on the body holder 37 on the turret 29, then sucked by the bottom holder 36 by vacuum suction, and the position R (see FIG. 9). While the metal can 11 is moving in the arrow direction Y (FIG. 11), the metal can 11 is pushed in the arrow P direction by the drive tool 43 before reaching the station B.
To the position L, and the end surface 11a and the bottom portion 11c contact the electrode piece 30 and the conductive brush piece 10c, respectively. At this point, the conductive brush 10 is in a contracted state, so that the metal can 11 is smoothly extrapolated to the rotating conductive brush 10.

Immediately after reaching the station B, the spindle 2, that is, the projecting piece 7, advances to move to the station C.
The conductive brush 10 expands by the time. Almost at the same time, as will be described later, with the rotation of the timing cam 55 (FIG. 12) attached to the spindle 20 for each spindle 2, a voltage is applied to the high voltage DC power supply 61 based on a signal 62 output from the proximity switch 56. When the application command signal 64 is input, electricity is conducted between the metal can 11 and the conductive brush 10. Since the expanded conductive brush 10 sweeps the entire inner surface of the metal can 11 except the flange portion while rotating, the defect inspection of the inner organic coating layer is immediately started, and the voltage application command signal 64 is transmitted before reaching the station D. It is turned off and the inspection ends.

During the passage between the stations D and E, the spindle 2 retracts and the conductive brush 10 contracts. Between the station E and the station F, the driving body 43 retreats and the metal can 11 moves to the position R.
Reach At the station F, the vacuum of the bottom holder 36 is released, and the metal can 11 moves to the reject turret 4
The metal can 11 ′ that has been determined to be “defective” in step 6 is removed at the station G. The metal can 11 determined to be “normal” moves to the delivery turret 47,
Delivered as a product.

Reference numeral 60 in FIG. 12 shows an electric circuit for defect inspection. While the detection unit 55a of the timing cam 55 attached to the main shaft 20 passes the front surface of the proximity switch 56, the proximity switch 56 outputs the rectangular wave pulse signal 62.
Is output to the latch circuit 63. When the latch circuit 63 outputs the voltage application command signal 64 to the high voltage DC power supply 61 based on the rising edge of the pulse signal 62, the DC power supply 61 causes the high voltage DC voltage (the voltage is usually 800 ~ 1000 volts) applied, resistance 65
The current flowing through is converted into a voltage by the current-voltage conversion circuit 66, and this voltage is amplified to the voltage V by the isolation amplifier 67.

FIG. 13 shows an example of a time-voltage curve in the case of a normal metal can 11 (the inner surface organic coating layer is made of a polyethylene terephthalate film having a thickness of 25 μm). The voltage V reaches the peak value Vs due to charging in the initial stage of voltage application, but thereafter gradually decreases. FIG.
Shows an example of a time-voltage curve when the metal can 11 having a defect in the inner surface organic coating layer is extrapolated, and the initial voltage peak value is almost the same as Vs in the case of FIG. However, at time t3 when the defect portion of the inner surface organic coating layer is detected,
Since the discharge current flows, the voltage V increases and the voltage peak value V
A pulse wave 57 of p is generated. FIG. 13 shows an example of a time-voltage curve in the case of defective conduction due to a trouble such as an organic coating adhered to the end face 11a, a disconnection of wiring, or a defective contact between the end face 11a and the electrode piece 30. The voltage peak value Vr due to the initial charging is lower than the voltage peak value Vs, and the voltage V drops rapidly.

Returning to FIG. 12, the voltage V is input to the film defect detection comparator 68 and the conduction defect detection comparator 69 (which detects that the end face 11a does not contact the electrode piece 30). The film defect detection comparator 68 has a voltage V1 set by the film defect detection voltage setting unit 70 (see FIG. 13).
Also enter. The voltage V1 is the voltage V at the time t2 required for the voltage V when the metal can 11 is normal to be substantially stable.
It is set to a value slightly larger than b (see FIG. 13). If the voltage V is higher than the voltage V1, AND from the comparator 68
The ON signal is output to the circuit 71.

A film defect detection start timer 72 is also connected to the input terminal of the AND circuit 71. The film defect detection start timer 72 has a time t2 (for example, 20 ms) from the rising time (time 0 in FIG. 13) of the rectangular wave pulse signal 62.
After ec) has passed, the ON signal is output to the AND circuit 71. Therefore, at time t3 after time t2, the peak value Vp
When a pulse wave 57 (FIG. 13) higher than the set voltage V1 is generated, an ON signal is input from the comparator 68 to the AND circuit 71, and the AND circuit 71 sets the latch circuit 73,
The latch circuit 73 outputs a signal 75 that "the metal can 11 has an inner surface coating defect". The signal 75 is input to a computer (not shown), and the computer outputs a reject signal when the metal can 11 reaches the station G (FIG. 11).

On the other hand, the signal 75 is input to the one-shot circuit 77 via the OR circuit 76. The pulse wave output from the one-shot circuit 77 is input to the R terminal of the latch circuit 63 via the OR circuit 78 to reset the latch circuit 63 and release the voltage application command signal 64. Therefore, the voltage application from the DC power supply 61 to the metal can 11 and the conductive brush 10 is released, and the conductive bush 10 is prevented from being damaged by the discharge after the time t3. The one-shot circuit 77
Signal is input to the R terminal of the latch circuit 73, and the latch circuit 73 is also reset.

The energization failure detection comparator 69 detects the voltage V
And the voltage V2 (see FIG. 13) set by the energization failure detection voltage setting device 79 are compared, and OFF when V <V2
The signal is output to the inverter 74, and the ON signal is output to the AND circuit 80. The voltage V2 is set to a value smaller than the voltage Va (see FIG. 13) at time t1 (t1 ≦ t2) when the metal can 11 is normal.

Reference numeral 83 denotes a current-carrying failure detection time setting timer for setting time t1. When time t1 is reached,
A pulse wave is output from the one-shot circuit 81 to the AND circuit 80, and the latch circuit 82 is set. Therefore, the latch circuit 82 outputs a signal 84 indicating “defective conduction”. The signal 85 is input to a computer (not shown), and when the metal can 11 reaches the station G, the computer outputs a reject signal.

The ON signal from the latch circuit 82 is input to the one-shot circuit 77 via the OR circuit 76 to generate a pulse wave. This pulse wave is input to the R terminal of the latch circuit 82 to reset the latch circuit 82, and at the same time O
The voltage is applied to the R terminal of the latch circuit 63 via the R circuit 78 to reset the latch circuit 63 and release the voltage application command signal 64. Therefore, the metal can 11 from the DC power supply 61
Further, the voltage application to the conductive brush 10 is released, and the conductive brush 10 is prevented from being damaged by the discharge after the time point t1. In the case of FIG. 13 where the end surface 11a of the metal can 11 contacts the electrode piece 30, V> V2, so the latch circuit 82 is not set and the "energization failure signal" 84 is not output.

When the metal can 11 is normal, the fall detection circuit 85 for the rectangular wave pulse signal 62 determines that the fall time t4 of the pulse signal 62 is t4 (t4>t2; t4 is 2 + 100 m, for example).
sec) is detected and an ON signal is output to the OR circuit 78. The output signal from the OR circuit 78 is R of the latch circuit 63.
Input to the terminal to reset the latch circuit 63 and release the voltage application command signal 64.

The present invention is not limited by the above embodiments. For example, the metal can may be one before the neck-in part and the flange part are formed, that is, the body part may have a straight tube shape as a whole. Alternatively, the conductive brush may be fixed and the metal can may be rotated. Further, the metal can may have only the inner surface coated with the organic coating layer.

[0036]

The apparatus of the present invention has the effect that defects in the inner organic coating layer of a metal can can be automatically detected at high speed by 100% inspection.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a main part of a device, which is an embodiment of the present invention, showing the vicinity of a conductive brush when the conductive brush is expanded.

FIG. 2 is a vertical sectional view taken along line II-II of FIG.

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

4 is a cross-sectional view taken along the line IV-IV in FIG.

5 is a vertical cross-sectional view taken along the line VV of FIG.

FIG. 6 is a vertical cross-sectional view of the main part showing the vicinity of the spindle on the left side of FIG.

FIG. 7 is a vertical cross-sectional view corresponding to FIG. 1, showing a contracted state of the conductive brush.

8 is a vertical cross-sectional view taken along the line VIII-VIII of FIG.

FIG. 9 is a front view of the main parts of an example of a device for feeding a metal can into the device shown in FIG.

10 is a vertical sectional view taken along line XX of FIG. 9 on the right side and taken along line X′-X ′ of FIG. 9 on the left side.

FIG. 11 is a schematic front view of a mechanical portion of an apparatus according to an embodiment of the present invention and its accessory device.

FIG. 12 is a circuit diagram of an embodiment of an electric circuit in the device of the present invention.

13 is a diagram showing a relationship between an energization time and an output voltage of an insulation amplifier in the electric circuit shown in FIG. 12, and FIG. 13 shows a case of a normal metal can having no defect in an inner organic coating layer. 13 is a diagram in the case of a metal can having a defect in the organic coating layer on the inner surface, and FIG. 13 is a diagram in the case of defective conduction between the electrode piece and the end face of the opening of the metal can.

[Explanation of symbols]

1a Conductive brush holder 1b Conductive brush holder 2 Spindle 6a Roll (means for expanding and contracting the conductive brush) 6b Roll (means for expanding and contracting the conductive brush) 7 Projection piece (expand the conductive brush, (Means for shrinking) 10 Conductive brush 11 Seamless metal can 19 First turret disc 22 Sun gear 23 Frame 30 Electrode piece 35 Can holder (means for inserting conductive brush on metal can) 43 Drive tool (on metal can) (Means for extrapolating conductive brush)

Front Page Continuation (56) References JP 63-11850 (JP, A) JP 62-242848 (JP, A) JP 53-69690 (JP, A) JP-B-3-30104 (JP , B2) J. Kohei 4-32609 (JP, Y2)

Claims (1)

(57) [Claims] 1. A defect inspection apparatus for an inner surface organic coating layer of a seamless metal can, at least the inner surface of which is coated with an organic coating layer, wherein the apparatus comprises a plurality of spindles to which a conductive brush holder is fixed, and a peripheral portion. Turret disk axially mounted along the axis; a sun gear that is fixed to a frame that supports the turret disk, meshes with a gear installed on the spindle, and rotates the spindle as the turret disk rotates; Means for externally attaching to a conductive brush; an electrode piece capable of contacting the opening end face of a seamless metal can having a conductive brush inserted therein; a DC power supply for applying a high voltage DC voltage between the conductive brush and the electrode piece; The conductive brush is shrunk during the period of extrapolation to the conductive brush and the period of detachment from the conductive brush, and at least a high voltage DC voltage is applied between the conductive brush and the electrode piece. Means for expanding the conductive brush during a certain period of time; and an electric circuit for detecting a pulse wave generated by a discharge based on a high DC voltage applied when the organic coating layer is defective. Defect inspection system for the inner organic coating layer of seamless metal cans.