JPH028261B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for detecting cracks in the flange of an end portion of a can, including the edge of the can body flange portion.

[Conventional technology]

The can body of a can for canning has a flange at its open end that extends diametrically outward over the entire circumference of the can body, and the peripheral edge of the lid is double-sealed to this flange. Completely sealed.

For forming this flange portion, a disk flange forming method in which a push-type jig is pushed into the can shaft, a roll flange forming method in which a rotary flange forming roll is brought into contact with the can end, etc. have been put into practical use.

However, when forming the flange part, flange cracks and notches (hereinafter referred to as flange cracks, including notches) are likely to occur on the edge of the flange part of the can body, and if there are flange cracks, the seaming part will be incompletely sealed. Problems arise such as bacteria and air entering the can through this area and spoiling the contents.

Therefore, can manufacturing process lines are usually equipped with a process for automatically detecting the presence or absence of flange cracks.

After the flange is formed at the end of the can body as described above, the can with the flange formed is moved from the flange formation point to the detection device installation point by means such as rolling or belt conveyance. , that is,
This is done by transporting the can to a detection point located at a location different from the location where the flange portion is formed. Some of the detection devices currently in use include those that utilize leakage or reflection of light, those that utilize changes in air pressure, and those that utilize changes in the strength of a magnetic field.

[Problems to be solved]

During this transfer, deformations can occur in the diametrically outwardly extending flange portions at the end of the can body. In most cases, this deformation is so slight that it does not interfere with forming a normal seamed part with the lid, but cans with this degree of deformation cannot be inspected by any of the above inspection methods. It is detected even when
Similar to cans with cracked flanges, they may be determined to be defective. This leads to an increase in loss rate and is not favorable for high-speed production.

SUMMARY OF THE INVENTION An object of the present invention is to provide a flange crack detection method that can eliminate the above inappropriate discriminating factors and reliably detect only cans with flange cracks at the flange ends.

[Means for solving problems]

The present invention is a method for detecting flange cracks immediately after forming a flange portion of a metal can body, which comprises a plurality of freely rotatable flange forming rolls 18 and a magnetic field fluctuation sensor 28 provided between the forming rolls 18. The can is fed to a can supply section where the axis of the head 12 and the can axis are parallel to each other, the can is rotated and approached toward the forming head 12, the end of the can is brought into contact with the forming roll, and the can is further pushed. , forming a flange portion at the end of the can, and after completing the formation of the flange portion at the end of the can, continuing to rotate the can once while maintaining the forming roll 18 and the can body in an engaged state; A magnetic field is applied in the axial direction of the can from the tip of the magnetic field variation sensor 28, which is installed close to the inner surface of the end portion including the edge of the flange, and the eddy current generated on the surface of the flange portion is used to suppress the eddy current at the flange crack portion. The amount of change in current is detected as a change in magnetic flux by the magnetic field fluctuation sensor, the signal from the magnetic field fluctuation sensor 28 is compared with a preset normal signal, and after being separated from the forming roll and returned to the supply position, it is determined that it is defective. A method for detecting flange cracks in a can, characterized in that the can is removed.

〔Example〕

A specific example to which the method of the present invention is applied will be explained with reference to the drawings. Fig. 1 is a sectional view of the main parts of a continuous flange forming apparatus equipped with a flange crack detector capable of carrying out the method of the present invention, Fig. 2 is a front view of one flange forming head, and Fig. 3 is the same as that of Fig. 2. - It is a cross-sectional view.

In FIG. 1, 1 is a main rotating shaft whose both ends are rotatably supported by support members (not shown), A is a can feeder fixed to the main rotating shaft at the center of the main rotating shaft 1, and A is a main rotating shaft. It consists of a well-known rotating turret 2 consisting of a cylindrical part 3 fixed to a rotating shaft 1 and can supporting parts 4 provided at equal intervals around the outer periphery of the cylindrical part 3. B is a flange molded part that is fixed to the main rotating shaft at the left side of the rotating turret 2 (as shown in the drawing), and C is a flange molded part that is fixed to the main rotating shaft 1 at the right side of the rotating turret 2 (as shown in the drawing). This is the can operating part.

The flange forming part B includes a disk 11 fixed to the main rotating shaft 1 and a rotating turret 2 of the disk 11.
a flanged head 12 secured to the side facing the
A flange forming head 12 is provided corresponding to each can support portion 4 of the rotating turret 2 (described later).

On the other hand, the can actuating part C is inserted into a main body part 40 fixed to the rotating shaft 1 and a through hole parallel to the rotating shaft 1 provided near the periphery of the main body part 40, and slides inside the through hole. A movable cylindrical portion 41, bearings 42, 42' fixed to both end portions of the cylindrical portion 41,
By means of the bearings 42, 42', a support rotating shaft 43 located within the cylindrical portion 41 and rotatably supported with respect to the cylindrical portion 41, and a supporting rotating shaft 43 fixed to the - side of the rotating turret 2 side. It consists of a push plate 44. Of these, the cylindrical part 41, the bearing 4
2, 42', a support rotation shaft 43, and a push plate 44 are provided in correspondence with each can support portion 4 of the rotary turret 2.

Although not shown, the device shown in FIG. 1 includes means for rotating the support rotation shaft 43, means for reciprocating the assembly part 45 including the support rotation shaft 43 within the through hole parallel to the main rotation shaft 1, and This is a through hole that passes through the support rotation shaft 43 along its axis and opens on the rotation turret 2 side of the push plate 44. The other end is connected to a pneumatic source, and the can bottom is sucked into the push plate 44 or the push plate is opened. 44. These means are well known in can printing presses and the like.

The structure of the flange molded part 12 will be explained with reference to FIG. 2 and FIG. A cylindrical portion 15, which is shaped like this, is located on the rotary turret 2 side of the disk 11, and is fixed to the disk 11 on the opposite side by a nut 17 that is screwed into a threaded portion 16 set in the fitting portion 14.

On the rotating turret side of the cylindrical portion 15, there are a plurality of flange forming rolls 18 whose center is concentric with the cylindrical portion 15 and installed at equal intervals. In this specific example, there are four forming rolls 18. The forming roll 18 integrally has a shaft 19 concentric with the forming roll, and the shaft 19 is inserted into a bottomed hole 20 provided in the cylindrical portion 15 and parallel to the main rotating shaft 1. It is rotatably supported within by upper and lower ball bearings 21 and 22. The upper and lower ball bearings 21 and 22 are formed by hollow liner cylinders 23, 24, 25 and a restraining plate 26.
It is fixed in the bottomed hole 20 by. The holding plate 26 is fixed to the upper surface of the cylindrical portion 15 by a central bolt 27.

The side surface of the forming roll 18 is the flange forming surface 3
5. This flange forming surface 35 is preferably made of a hard material.

The flange forming head 12 has a sensing portion 28 of a flange crack detector (not shown) between two forming rolls 18. The sensing section 28 is a magnetic field generator that senses changes in the magnetic field, and the sensing section 28 has a tapered tip and a distal end 2 that combines a transmitting coil and a receiving coil.
This is an eddy current sensor with 9, and the detection principle for sensing the change in magnetic flux due to the amount of change in eddy current generated on the surface of a conductor, whether magnetic or non-magnetic, is the same as that of a normal sensor. Reference numeral 30 designates a guide component for the sensing portion 28, which is inserted and fixed into the holding plate 26 from the cylindrical portion 15 side, and its upper surface 31 is on the same plane as the lower end surface 32 of the flange forming surface 35 of the forming roll 18. The guide part 30 has a sensing portion 28.
The distal end 29 of is inserted. The distal end surface 33 of the distal end portion 29 is located slightly deeper into the assembly part than the upper surface 31 of the guide component 30 and faces the end portion including the edge of the flange portion formed by the forming roll 18. It is located.

The device constructed as described above operates as follows.
First, cans are fed into the rotating turret 2 shown in Fig. 1 with the opening side of the metal can placed on the left side to the can support part 4 on the back side of the figure, and the main rotating shaft 1 is connected to the device shown in Fig. 1 from the right side. While rotating in a direction that results in clockwise rotation when viewed, the assembly 45 is advanced towards the rotating turret 2 so that the push plate 44 is attached to the bottom of the can on the can support portion 4.
are brought into close contact, the can is suctioned against the pusher plate 44, and the can is further advanced toward the flanging head 12. At this time, since the support rotation shaft 43 is rotating, the can also rotates around the can axis together with the support rotation shaft 43. Four forming rolls 18 enter inside this rotating can, and the open end of the can contacts the flange forming surface 35 of the forming roll. Here, since the can is rotating, the forming roll 18 is also rotated due to the frictional resistance with the open end of the can.

When the can is further advanced, the open end of the can is pushed out along the flange forming surface 35, reaches the lower end surface 32 of the flange forming surface 35, and is extended diametrically outward, thereby forming the open end of the can body. A flange portion is formed on. In this equipment, flange forming is performed by forming roll 1.
The can is rotated three times from the time 8 contacts the open end of the can to the end of molding, and after the molding is completed, in order to stabilize the flange molding dimensions, the can is held at the molding end position and the axial direction of the can is aligned with the molding roll. In other words, the assembly part 45 is stopped during the familiarization rotation in which the press plate 44 makes one more rotation at a position where the assembly part 45 is brought close to the rotating turret 2, and then the retraction movement is started. Advance, stop, and retract motion of this assembly is provided by the configuration of a cam plate (not shown).

The can being sucked by the push plate 44 is separated from the flanging head 12 as the push plate 44 retreats.
The rotating turret 2 returns to its original position. At this point, the suction of the can is released, and the push plate 44 is further retreated slightly and separated from the can. The cans are supported by the can support portion 4 of the rotating turret 2 and are sent to the next process by the rotation of the rotating turret.

As described above, the above-mentioned specific example device is equipped with a magnetic field fluctuation sensor 28 in the flange forming head 12,
The tip surface 33 of the sensor 28 is the flange portion 50 of the can.
(See Figure 3) is provided close to and facing the end portion including the edge 51 of the flange, and immediately after the above-mentioned flange forming is completed, the can rotates once at the forming end position to stabilize the flange dimensions. During this time, the presence or absence of flange cracking is detected based on the signal from the sensor for one rotation of the can. That is, when the above-mentioned can immediately after flange forming is rotated once, if there is no flange crack at the flange end after the flange portion has been formed, a signal is sent from the sensor 28 to a discriminating device of a detector (not shown). has a nearly constant shape, but if there is a crack in the flange, the pattern of eddy current generated at the cracked flange will be different, and the signal output from the receiving coil will have a shape different from the constant signal in the normal case. become the property of

The signal for one rotation of the can output from the sensor 28 is amplified by an amplifier according to the electric circuit within the detector, then passed through a filter to shape the waveform, and is discriminated so that a pass/fail signal is output. A can having a flange crack at the end of the flange is removed from the can transfer path after coming out of the rotating turret by a known can removing means which operates after a predetermined time after the output signal from the sensor 28 is processed by the detector.

Note that the number of flange forming rolls is not limited to four,
Depending on the can diameter, 5, 6, or 3 pieces may be used depending on the can diameter.

〔effect〕

That is, according to the present invention, immediately after flanging with the flange forming roll (that is, immediately after the forward movement of the can actuating section C has stopped), the can is further removed at the forming end position (the position where the can operating section C has stopped). In the run-in step, which stabilizes the flange dimensions by one rotation, the tip surface is brought close to the end of the flange of the can engaged with the forming rolls, and a magnetic field fluctuation sensor with a tapered tip located between the forming rolls is used to detect the can. Since this method detects the presence or absence of flange cracks based on signals from one round, it has the following advantages.

(1) Magnetic flux is applied to the flange end in spots, preventing ink stains, pellets (paint scum), and other detection elements other than flange cracks from entering, allowing for discrimination and detection.

In addition, it is possible to detect even the slightest deformation of the flange, which tends to occur during transportation of cans to a separate detection device after flange forming, so even cans that are not completely sealed during seaming can be defective. This avoids the inconvenience of identifying it as a can, and only detects the presence or absence of a flange crack element that would result in incomplete sealing.

Therefore, the detection accuracy of flange cracks is improved,
The proportion of good cans mixed in among cans determined as defective cans can be minimized, and the loss rate can be reduced.

(2) After flange forming, a sensor is placed between the forming rolls to detect cracks in the flange, taking advantage of the positioning of the axial direction of the can while the forming rolls are rotating to stabilize the flange dimensions. Since it is incorporated into the system, it is possible to detect flange cracks with high precision using inexpensive and compact equipment that does not require special detection equipment.

(3) Moreover, since the detection process can be used also as the flange dimension stabilization process, the time required for the process can be shortened, which is advantageous for high-speed continuous production.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of the main part of a continuous flange forming apparatus equipped with a flange crack detector, FIG. 2 is a front view of one flanged part, and FIG. 3 is a cross-sectional view taken from FIG. 2. 35... Flange forming surface, 18... Forming roll, 50... Flange part, 51... Flange part edge, 28... Magnetic field fluctuation sensing part, A... Can feeding part,
B...Flange forming part, C...Can operating part, 2...
Rotating turret, 12...flange molded part.

Claims (1)

[Claims] 1. A method for detecting flange cracks immediately after forming a flange portion of a metal can, which comprises a plurality of freely rotatable flange forming rolls 18 and a magnetic field fluctuation sensor 28 between the forming rolls 18. The cans are fed to a can supply section in which the axis of the forming head 12 provided is parallel to the can axis, and the can is brought close to the forming head 12 while rotating so that the end of the can is brought into contact with the forming roll. The can is pushed in to form a flange at the end of the can, and after the flange at the end of the can is formed, the can is continuously rotated one more time while maintaining the forming roll 18 and the can body in an engaged state. A magnetic field is applied in the axial direction of the can from the tip of the magnetic field fluctuation sensor 28, which is provided close to the inner surface of the end portion including the edge of the flange portion, and the eddy current generated on the surface of the flange portion detects the cracked portion of the flange. The amount of change in eddy current at 28 is detected as a change in magnetic flux by the magnetic field fluctuation sensor, the signal from the magnetic field fluctuation sensor 28 is compared with a preset normal signal, and the roller is separated from the forming roll and returned to the supply position. A method for detecting cracks in a flange of a can, characterized in that a defective can is then removed.