JPH0549066B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a device that is incorporated into a multilayer material manufacturing apparatus and continuously detects insulation defects in the multilayer material. More specifically, the present invention can be incorporated at an appropriate position in a production line to eliminate defects that occur during electrical resistance welding of multilayer materials without the influence of electrical continuity such as support rolls, rolling rolls, or bridle rolls. The present invention relates to a device for online checking whether or not

(Prior Art) In recent years, reducing noise from many noise-generating machines, such as transportation machines, processing machines, and electrical products, has become a major issue. On the other hand, from the standpoint of resource saving,
Machines are becoming lighter, and lightweight materials are in demand. This trend is expected to further expand in the future.

As a solution to both of these problems, it has been found that the use of multilayer materials, such as composite damping steel plates called Sanderutsch steel plates, is highly effective. Active research and development is being carried out in order to further improve the material and to improve other characteristics according to specific uses. Here, the composite damping steel plate has a sandwich structure in which a core resin material, which is a viscoelastic substance, is sandwiched between two upper and lower steel plates (hereinafter simply referred to as "skin steel plate" or "skin metal plate"). It is a kind of multi-layered material.

In addition, as another form of sand German steel plate, an expensive metal plate such as a stainless steel plate or a titanium plate and an inexpensive metal plate such as a cold-rolled steel plate or a plated steel plate are laminated on both sides of the core resin material via an adhesive layer. There is something.
These sandwiched steel sheets laminated with dissimilar metal plates are not only useful industrially from the standpoint of resource conservation, but also
It is also a multi-layer material that takes advantage of the characteristics of each skin metal plate and has excellent functions such as corrosion resistance and design.

Furthermore, by increasing the thickness of the core resin material, it is also possible to produce a Sanderutsch steel plate with further enhanced functions such as weight reduction and heat insulation.

As described above, in this specification, the multilayer material includes a sandwiched metal plate, but the sandwiched metal plate includes not only one in which at least one side is a steel plate, but also both made of a non-steel metal plate. Although a sandwich metal plate is also included, for convenience of explanation, an example in which a steel plate is used as both skin metal plates will be described below.

(Problems to be Solved by the Invention) After manufacturing, these Sanderutsch steel plates are formed into a desired shape using a press or the like and then assembled into a final product, and a joining technique is employed during the assembly. One such joining method is electric resistance welding such as spot welding and projection welding. However, since the resin constituting the core resin material is generally electrically insulating, it is essential to provide a short circuit (shunt circuit) between one metal plate and the workpiece during electrical resistance welding.

However, if a conductive substance gets mixed into the core resin material that serves as the electrical insulating layer, resulting in poor insulation between the upper and lower skin metal plates, stray current will occur at that location, causing defects such as burns and through holes. .

The generation of this stray current will be explained with reference to FIG. For example, skin steel plates 1, 1' and core resin layer 2
When spot welding the sand German steel plate 3 and the ordinary steel plate 5, which are made of The flow follows a path such as chip 7 → upper skin steel plate 1 → short circuit 6 → ordinary steel plate 5 → lower electrode chip 7'. At this time, Joule heat is generated in the vicinity of both electrode chips 7 and 7', and since both electrode chips are pressurized, the core resin layer 2 that has been softened or melted by the Joule heat is expelled from between the electrode tips. . Therefore, both skin steel plates 1 and 1' come into contact (not shown), and current flows as shown by the thick solid line in the figure.
As with normal spot welding, a nugget is formed and the welding is completed. However, the core resin layer 2
The situation is different when conductive foreign matter 4 is mixed in. In other words, in addition to the short-circuit current shown by the double broken line mentioned above, in addition to the short circuit current shown by the double broken line, there is also a short circuit current caused by the upper electrode chip 7 → upper skin steel plate 1 → conductive foreign matter 4 → lower skin steel plate 1' → ordinary steel plate 5 → lower A shunt occurs in the path leading to the electrode tip 7'. This is a so-called stray current. When this shunt occurs, Joule heat is generated in the conductive material 4, causing burns or, in severe cases, through-holes. This phenomenon is the same in both AC and DC resistance welding. Such conductive foreign substances include unavoidable dust from manufacturing plants, scratches on steel plates, substances mixed in resin, and the like. Therefore, the probability of occurrence of the above-mentioned defects during welding is higher in a sand German steel plate in which the intermediate intervening layer of the core resin material is thinner.

Considering that electric resistance welding is often used as a joining method for sand German steel plates, it is desirable to establish an inspection method that completely checks for such defects at the manufacturing stage, as such defects can be fatal.

However, methods for detecting conductive substances (insulation defects) that cause burns or through-holes include methods using soft X-rays and ultrasonic waves, but these methods are as follows. It has some disadvantages.

In other words, the size of the conductive foreign matter is generally several hundred micrometers or less, which is very small compared to the overall thickness of the Sanderutsch steel plate, and it is necessary to spend time and detail to inspect it using the method described above. , it is unsuitable for full product inspection or online inspection. However, as mentioned above, the through-holes may become a fatal defect depending on the use of the Sanderutsch steel plate, so a full product inspection or on-line inspection is indispensable. In addition, it is quite conceivable that insulating foreign matter that does not cause the formation of through-holes as described above may be unavoidably or intentionally mixed into the core resin layer during bonding, but soft X-ray method, ultrasonic It is extremely difficult to distinguish between these conductive foreign substances and insulating foreign substances using methods such as the above.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a detection device that can reliably and easily detect insulation defects in upper and lower skin metal plates that cause the occurrence of through holes as described above.

(Means for Solving the Problems) The insulation defect detection device according to the present invention detects insulation defects in a multilayer material formed by interposing an insulating material layer between two metal plates. an apparatus for continuously detecting conditions, comprising: (a) a current source; and (b) a pair of conductive conductors connected to the current source and in electrical contact with upper and lower metal plates of the composite material, respectively. (c) two pairs of conductive rolls disposed on both sides of the pair of rolls in (b), each pair electrically contacting the upper and lower metal plates of the multilayer material, respectively; (d) The pair of rolls in (b) above and the two pairs of rolls in (c) above arranged on both sides of the rolls form an integral closed circuit, and the two pairs of rolls in (c) above form an integral closed circuit. The method is characterized by comprising: means for detecting a voltage difference between each pair of rolls; and (e) means for comparing the voltage difference detected in (d) with a predetermined value.

The above-mentioned inspection device can be placed at an appropriate position on the production line after constructing the multi-layer sandwich metal plate. For example, it can be installed on the exit side of the shear line, and the inspection device can be placed on the output side of the shear line to continuously inspect the sheets one by one after cutting them to a predetermined length. The test may be performed either individually or continuously prior to winding into a coil by placing it on the exit side of a slitter or trimmer.

Thus, with the device according to the invention, the entire amount of multilayer material can be inspected on-line.

(Function) Under normal conditions, the current supplied from the current supply source passes through the circuit formed by the pair of rolls (b), the upper and lower metal plates of the multilayer material, and the stands that support the multilayer material on both sides. Flowing. Therefore, the voltage difference between each pair of the two rolls in (c) detected in (d) above is approximately a constant value (the circuit formed in normal times is symmetrical with respect to the pair of rolls in (b)). , this constant value is 0).

Here, it is assumed that the location where foreign matter or the like has entered the insulating layer of the multilayer material and an insulation defect has occurred is located between one of the two pairs of rolls in (c) above. In this case, since the resistance value of the poor insulation spot is smaller than the resistance value of the stand, etc., a short circuit occurs through the spot, and the voltage drops rapidly between the rolls passing through the poor insulation spot. As a result, the comparing means (e) detects that the voltage difference has fluctuated beyond a predetermined value, and an insulation failure of the material is detected.

If an insulation defect is detected in this manner, measures are taken such as marking the relevant location on the multilayer material with a marker and notifying the operator using a warning lamp.

(Example) Next, an example of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows a combination of a schematic side view and a block diagram of a device according to the invention installed between roll stands.

In the figure, a pair of roll stands 10a,
Sanderutsch steel plate 3, which is a multilayer material, advances between 10b. The sand German steel plate 3 is constructed by sandwiching a core resin layer 2, which is an insulating material, between two skin steel plates 1 and 1'. There are places in the resin layer 2 where conductive foreign matter 4 may be mixed in, causing insulation failure.

A pair of current supply rolls A1 and A2 electrically connected to the constant current source 11 are made of a conductive material and are in contact with the upper and lower skin steel plates 1 and 1', respectively, in the middle of the stands 10a and 10b.

Furthermore, two pairs of conductive voltage detection rolls B1,
B2, C1, C2 are provided on both sides of the current supply rolls A1, A2, and each pair is in contact with the upper and lower skin steel plates 1, 1', respectively.

These rolls A1, A2, B1, B2, C
1 and C2 constitute an integrated closed circuit, and all of their rolls are held in an insulated state (except through the steel plate 3) of the stands 10a and 10b. Phosphor bronze was used as the material for these rolls.

The voltage detection roll pair B1, B2 is connected to each input of the differential amplifier 13B, respectively. The other roll pair C1, C2 is similarly connected to each input of the differential amplifier 13C.

Thus, each amplifier 13B, 13C has an output proportional to the voltage between roll pairs B1, B2 and C1, C2, respectively. Amplifier 13B, 13
The C output is input to the differential amplifier 15, and the resulting output proportional to the difference between the two voltages is input to the comparator 1.
7, it is compared with a predetermined value.
As a result of this comparison, if it is determined that the output of the amplifier 15 exceeds a predetermined value, a marker is activated to mark the corresponding location on the steel plate 3, and a warning lamp is lit to notify the operator. Further, the output of the amplifier 15 is continuously recorded by a recorder (magnetic tape or the like).

FIG. 2 is an equivalent circuit diagram of the apparatus of FIG. 1 in a normal state (no foreign object 4). In the figure, R ₁ : resistance between current supply rolls A1, A2 and each voltage detection roll B1, B2, C1, C2 via skin steel plates 1, 1', R ₂ : each voltage detection roll B1, B2, C1 ,C2
and the resistance between the roll stands 10a, 10b through the skin steel plates 1, 1', R _s : resistance between the upper and lower sides of each roll stand 10a, 10b.

As is clear from the symmetry in the figure, under normal conditions the voltages detected by the differential amplifiers 13B and 13C are equal, so the output of the amplifier 15 is 0.
be equivalent to.

FIG. 3 is an equivalent circuit diagram of the apparatus shown in FIG. 1 when the conductive foreign object 4 is passing between the rolls B1 and B2. Let R _f be the short circuit resistance between rolls B1 and B2 caused by the foreign object 4. Since R _f is generally much smaller than 2R ₂ +R _s (R _f <<2R ₂ +R _s ), roll B
The resistance 2R ₂ +R _s between 1 and B2 can be omitted.

Using the equivalent circuit shown in Figure 3, foreign matter 4 is transferred to roll B.
Calculating the voltage V _B between rolls B1 and B2 and the voltage V _C between rolls C1 and C2 when passing between rolls B1 and B2, V _B =I・R _f (2R ₂ +R _f )/(R _f +R _p
+4R ₁ ) V _C =I·R _p (2R ₁ +R _p )/(R _f +R _p +4R ₁ ) (where, R _p =2R ₂ +R _s . The steady-state current value supplied by the current source 11 is set as I. ) The outputs of differential amplifiers 13B and 13C are respectively
Proportional to V _B and V _C. However, in this case, since R _f is very small, V _B is almost equal to 0. Since the output of the differential amplifier 15 is proportional to V = V _B - V _C , the output when a foreign object passes is approximately -V _C = -I・R _p (2R ₁ + R _p ) / (R _f + R _p + 4R ₁ ) and varies greatly from its normal value (i.e. 0).

Even when the foreign object 4 passes between the rolls C1 and C2, the output of the differential amplifier 15 greatly fluctuates from its normal value.

The comparator 17 activates a marker and lights a lamp when the fluctuation width of the amplifier 15 exceeds a predetermined value.

FIG. 4 is a perspective view showing a specific configuration of the roll portion of the device shown in FIG. 1. FIG. The rolls (A2, B2, C2 in FIG. 1) that contact the lower surface of the steel plate 3 are rotatably fixed to the detection stand 20, but the upper rolls A1, B1, C1 are rotated in the direction of the steel plate 3 by an air cylinder 21. (At the start of sheet threading, roll A
1, B1, and C1 upward). Further, electrical connection to each roll A1, A2, B1, B2, C1, C2 is made via a slip ring 22.

Note that in order to detect insulation failure over the entire width of the steel plate, it is sufficient to install a plurality of devices in which the position of the roll is displaced in the width direction.

(Effects of the Invention) In the present invention, a constant current is supplied to the rolls A1 and A2 from a constant current source, and the difference V B between the voltage V _B between the roll pair B1 and B2 and the voltage V _C between the roll pair C1 and _C2
The presence or absence of insulation failure is determined based on whether the variation in the amount corresponding to -V _C exceeds a predetermined value.

Since it is configured to supply a constant current and detect the voltage (difference), it is virtually free from the negative effects of noise caused by changes in contact resistance between the roll and the Sandersch steel plate (multilayer material). Insulation defects in moving materials can be efficiently detected with extremely high accuracy.

FIG. 5 shows an example of a graph recording the output V of the differential amplifier 15 of the device of the present invention (arbitrary reference voltage, line speed 20 m/min, skin steel plate thickness 0.8 mm, resin thickness 50 μmm). . In the figure, V _f is foreign object 4
It shows a large variation in the output V due to the passage of . As can be seen from the figure, the S/N ratio in the present invention is high, and the reliability of determining insulation failure is high.

[Brief explanation of drawings]

FIG. 1 is a combination of a schematic side view and a block diagram of the device according to the present invention installed between roll stands, and FIGS. 2 and 3 are equivalent circuit diagrams of the device in FIG. 4 is a perspective view of the roll portion of the device shown in FIG. 1, FIG. 5 is a graph showing the temporal change in the voltage difference between the rolls detected by the device shown in FIG. 1, and FIG. 6 is a perspective view of the roll portion of the device shown in FIG. FIG. 3 is a schematic cross-sectional view showing a mechanism in which stray current flows to a defective insulation location when spot welding is performed. 1, 1': Skin steel plate, 2: Core resin layer, 3:
Sand German steel plate, 4: Conductive foreign matter, 10a, 1
0b: Stand, 11: Constant current source, 13B, 13
C, 15: Differential amplifier, 17: Comparator, A1, A
2: Current supply roll, B1, B2, C1, C2:
Voltage detection roll.

Claims (1)

[Scope of Claims] 1. A device that continuously detects insulation defects in a multilayer material constructed by interposing an insulating material layer between two metal plates while the multilayer material is progressing, a) a current supply source; (b) a pair of conductive rolls connected to the current supply source and in electrical contact with the upper and lower metal plates of the multilayer material, respectively; and (c) the pair of (b) above. two pairs of conductive rolls disposed on both sides of the roll of (b), each pair electrically contacting the upper and lower metal plates of the multilayer material; (d) the pair of (b) above; The roll and the two pairs of rolls (c) disposed on both sides of the roll form an integrated closed circuit, and means for detecting the difference in voltage between each pair of the two rolls (c). and (e) means for comparing the voltage difference detected in (d) with a predetermined value. A device for detecting insulation failure in a multilayer material, comprising: (e) means for comparing the voltage difference detected in (d) above with a predetermined value.