JPH03236953A - Manufacture of vibration-damping steel plate - Google Patents

Abstract

PURPOSE:To secure productivity stably and efficiently and manufacture vibration- damping steel plate of superior resistance welding properties by carrying out contact bonding while applying pulse to conductive particles mixed with two steel plates, upper and lower, and resin in an intermediate layer in the after-process of pressure rollers. CONSTITUTION:Conductive particles for securing sufficiently electric resistance welding properties are mixed into resin of an intermediate layer. The setting positions of current applying rollers are basically at the time when bonding of vibration-damping steel plates is completed, that is, the after-process of pressure rollers, in order to secure sufficiently the bonding properties of vibration-damping steel plates. The two steel plates, upper and lower, can be bonded with the conductive particles without melting or spraying the conductive particles by applying pulse-like current to vary the current value discontinuously. Also, the resin remaining in the vicinity of the bonding section of the conductive particles and two steel plates, upper and lower, is heat decomposed by applying said pulse-like current, and good welding properties can be provided by electrically recontacting by means of pressurizing force at the time of welding, even if the bonding section is removed off after contact bonding by means of a plurality of pressure rollers.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for producing a damping steel plate that has excellent resistance weldability, such as spot I-welding.

(Prior Art) A constrained vibration-damping steel plate in which a viscoelastic resin is sandwiched between two thin steel plates as an intermediate layer absorbs energy during vibration by transferring energy from the resin (hereinafter referred to in this specification) as the intermediate layer. "Middle class legs"
Since the vibration is absorbed by the shear deformation of the intermediate layer resin, it has excellent vibration damping properties even when the thickness of the intermediate layer resin is thin, and has been actively put into practical use in recent years.

However, the drawback of this restraint-type damping steel plate is that the intermediate layer resin is an insulator, so resistance weldability is poor. The intermediate layer resin was softened by energizing in advance, and then the main energizing was performed as indicated by the thick arrow in the figure, thereby ensuring resistance weldability.

However, since the technology to provide this bypass circuit increases the number of man-hours when there are many welding points, in recent years, restraint type technology has been developed in which conductive particles such as metal powder or graphite powder are mixed into the intermediate layer resin. A shaken steel plate has been developed (
"Sumitomo Metals" vol. 41, No. 1, No. 111~
(Page 118 “Development of weldable vibration damping copper plate”). In this technology, as shown in a schematic cross section in Fig. 3, a current flows through relatively human-shaped conductive powder mixed in the interlayer resin, and the heat generated by the conductive powder causes the interlayer resin to This is a technique that allows direct resistance welding without providing the bypass circuit by softening the weld.

In this technique, as shown in FIG. 3, it is necessary to electrically connect two upper and lower thin steel plates to each other using relatively large conductive particles mixed in an intermediate layer resin. Therefore, in order to sufficiently ensure resistance weldability in such a damping steel plate, it is most important to control the contact status between the conductive particles and the two upper and lower steel plates.

On the other hand, as for the manufacturing method of the above vibration damping steel plate, the manufacturing process is schematically shown in FIG. 5(a) or FIG. 5(1)) ("
Tetsu to Hagane JVO], 73, No. 1.3 (1987) No. 3
(Excerpt from page 62 “Equipment overview for coil-type damping steel plates”)
As is clear from the figure, two thin steel plates (upper and lower) were preheated to a temperature higher than the binding temperature of the intermediate layer resin, and a resin film that would become the intermediate layer resin was sandwiched between the two 1 m plates (Figure 5). a
)) Alternatively, the -C method is to temporarily press the upper and lower steel plates together in advance (Fig. 5 (b)), and then press the upper and lower two thin steel plates and the intermediate layer resin using a press roll. It is.

However, when using such a conventional manufacturing method for damping steel plates, since the intermediate layer resin is a viscoelastic resin, problems may occur in the contact situation between the above-mentioned two upper and lower thin steel plates and the conductive particles. There is.

Specifically, in FIG. 4, which schematically shows the relationship between the thin steel plate, the conductive particles, and the resin in the damping steel plate, melted and softened intermediate layer resin is placed in the contact area between the upper and lower two thin steel plates and the conductive particles. will remain, and furthermore, this remaining resin will not be completely discharged during compression bonding. therefore,
At the contact portion between the two thin steel plates and the conductive particles mixed in the intermediate layer resin, the resin may remain, although it is an extremely thin layer. In such a case,
The conductivity of the resulting damping steel plate deteriorates, causing poor resistance weldability.

As a countermeasure against defects in resistance weldability of vibration-damping steel plates caused by residual resin at the contact area between two thin steel plates and the conductive particles mixed in the intermediate layer resin, for example, Japanese Patent Laid-Open No. 6
There is a technique proposed in Publication No. 4-56541.

This is a technique in which two upper and lower steel plates and an intermediate layer resin are crimped together, and then the steel plates and the intermediate layer resin are crimped while being continuously energized by an energized roll.

(Problem to be Solved by the Invention) However, as a result of further examination by the present inventors, the technology proposed in this Japanese Patent Application Laid-open No. 64-56541 does not allow continuous energization in advance by using an energizing roll. It has been found that a problem arises in that stable bonding cannot be achieved.

In other words, specifically, when a current of more than the amount required to join the conductive particles in the intermediate layer resin and the two upper and lower steel plates is passed, the particle size of the conductive particles is small. These conductive particles melt and scatter, making it impossible to form a satisfactory bond. On the other hand, if a low current is applied to prevent such melting and scattering of the conductive particles, the bond between the conductive particles and the two upper and lower steel plates will be compromised. .

The purpose of the present invention is to solve these problems, that is, when manufacturing the vibration damping steel plates continuously by a roll crimping method, the conductive material mixed in the two upper and lower i-plates and the intermediate layer resin can be removed. It is an object of the present invention to provide a method for manufacturing a split steel plate that stably and efficiently ensures conductivity between the particles and has excellent resistance weldability such as spot welding.

(Means for Solving the Problems) In order to achieve the above object, the present inventors have made extensive studies and have obtained new findings not shown in (1) and (2) below. In other words, ■ By passing the current in the current-carrying roll as described above continuously as in the conventional method, that is, by passing a pulsed current in which the current pattern changes intermittently, unlike continuous waves such as sine waves and direct current,
- The lower two steel plates and the conductive particles can be joined without melting or scattering the conductive particles, and ■ Furthermore, by applying this pulsed current, the conductive particles and the upper and lower two steel plates can The resin remaining near the joint will thermally decompose, so even if the crimped part peels off, the pressure during resistance welding will ensure electrical contact and good weldability.Of course, the resin will thermally decompose. In the case of this pulsed energization, the range is limited to the vicinity of the joint, so that the adhesive strength between the upper and lower two steel plates and the intermediate layer resin and the damping properties of the resulting damping steel plate do not deteriorate.

As a result of further examination based on these new findings,
To put it simply, in the technology proposed in Japanese Patent Application Laid-Open No. 64-56541, a vibration-damping steel plate with excellent resistance weldability can be produced by using a pulsed current instead of a continuous current to flow through the current-carrying roll. The present invention was completed based on the finding that it is possible to produce continuously, stably, and even efficiently.

Here, the gist of the present invention is to provide a method for continuously manufacturing a vibration-damping steel plate consisting of two steel plates and an intermediate layer resin between them, and in which conductive particles are mixed in the intermediate layer resin. After or during the crimping of the two steel plates and the intermediate layer resin, the two
This method of manufacturing a vibration damping steel plate is characterized in that the two steel plates and the intermediate layer resin are joined by applying a pulsed current while pressing the two steel plates and the intermediate layer resin.

In the present invention described above, "pulsed current" refers to a current whose current value changes intermittently, unlike a continuous wave such as a sine wave or direct current, and specifically refers to a current that changes intermittently in the connection between conductive particles and a steel plate. This refers to a current pattern in which a peak current that serves as a conductive particle is alternately repeated, followed by a low current (which may be zero) that serves to prevent conductive particles from melting and scattering.

That is, according to the present invention, in the process after the crimping roll, or in the process located between the crimping rolls in the case of a plurality of crimping rolls, or in the process after the crimping rolls, an energizing roll capable of pulse energization is provided, and the upper and lower parts are connected to each other. By crimping two steel plates and the conductive particles mixed in the intermediate layer resin while applying pulse current, it is possible to manufacture a vibration damping steel plate in a state where direct current can be applied stably.

(effect) Hereinafter, the present invention will be explained in detail together with its effects.

As mentioned above, the present invention is an improved invention of the invention proposed in JP-A No. 64-56541, and more specifically, it consists of two steel plates and conductive particles mixed in the intermediate layer resin. When producing vibration-damping steel plates continuously, after or during the crimping of the two steel plates and the intermediate layer resin, the two steel plates and the intermediate layer resin are crimped using a roll that can be energized. This invention is characterized in that the two steel plates and the intermediate layer resin are joined by applying a pulsed current instead of a continuous current.

First, the structure of the damping steel plate obtained by the present invention will be briefly explained. This damping steel plate is completely different from conventionally widely known damping steel plates.

A steel plate consisting of two thin steel plates serving as the skin and a viscoelastic resin sandwiched between them. Contains conductive particles to ensure sufficient properties.

There are no restrictions on the material, shape, etc. of the steel plate, as long as it can ensure conductivity. For example, the composition may be low alloy mesh, high alloy steel, etc., but depending on the application, non-ferrous metals such as Cu, Ti, etc. may be used. Although there are no particular restrictions on the thickness of the steel plate used, thin steel plates (cold-rolled, hot-rolled, surface-treated steel plates, etc.) with a thickness of about 0.2 to 2 mm are used for boat fishing. I can give an example.

Further, there are no particular restrictions on the material of the intermediate layer resin, and any material may be used as long as it can sufficiently ensure the vibration damping properties of the ML plate. For example, materials such as polyester, acrylic, polyolefin urethane, and PVC,
As for the thickness of the layer, an intermediate layer resin having a thickness of about 10 to 100 p can be exemplified.

Furthermore, the conductive particles mixed in the intermediate layer resin are used to ensure sufficient electrical resistance weldability of the damping steel plate without providing a bypass circuit, as described above. Therefore, it is important that the particle size of the conductive particles mixed in the intermediate layer resin is approximately the same as the thickness of the intermediate layer resin.
This is desirable from the viewpoint of ensuring that the upper and lower two steel plates are in contact with each other via conductive particles as shown in the figure. Incidentally, the particle size of the conductive particles in the present invention is, of course, an average particle size, and sizes around this range can be allowed to some extent. Specifically, when the thickness of the intermediate layer resin is about 50 μm, the particle size of the conductive particles can be exemplified to be about 40 to 100 p.

In addition, as the electrically conductive particles that can be used in the present invention, specifically, electrically conductive particles such as stainless steel powder, Ni powder, Zn powder, and iron powder can be exemplified.

Next, the method for manufacturing a vibration damping steel plate according to the present invention will be described in FIGS. 1(a) and 1(b), which are schematic illustrations of the manufacturing process.
).

In Fig. 1(a) and Fig. 1(b), an upper steel plate and a flat steel plate that provide two steel plates above and below the damping steel plate, and a resin-based steel plate sandwiched between the two steel plates are shown. The damping films are each unwound and joined together by a pressure roll. In the embodiment shown in FIG. 1(a), there is one pressure roll, but in the embodiment shown in FIG. 1(b), there are two pressure rolls. Regarding the number of crimping rolls,
The present invention does not require any limitation, and it is sufficient if there is one or more. Therefore, if necessary, a plurality of them may be installed and used in succession.

Furthermore, the installation position of the current-carrying roll used in the method of manufacturing a damping steel plate according to the present invention is basically the point at which the joining of the obtained damping steel plate is completed, that is, as shown in FIG. 1 (a).
), it is desirable to perform the process after the pressure roll from the viewpoint of ensuring sufficient bondability of the damping steel plate. However, when there are a plurality of crimping rolls in the crimping equipment as shown in FIG. 1(b), it may be applied after the plurality of crimping rolls or between the plurality of crimping rolls.

The reason for this is that in the method for manufacturing a vibration-damping steel plate according to the present invention, pulse energization, which will be described later, is performed because it heats not only the resin present at the joint between the steel plate and the conductive particles, but also the resin present in the vicinity. Therefore, if the roll that applies the pulse current is located in the middle of the crimping port 1 group, and the joint part peels off during subsequent crimping with the crimping roll, thermal decomposition may also occur. The area of the resin thus applied is wide, and the two steel plates and the intermediate layer resin are sufficiently bonded within this range, so that the bondability of the obtained damping steel plate is sufficiently ensured.

In addition, in the present invention, the reason why a pulsed current is used instead of a continuous current as the current passed by the current-carrying roll is as described above. Unlike continuous waves such as sine waves and direct current, the current value changes discontinuously. By applying a pulsed current, it is possible to bond the upper and lower steel plates to the conductive particles without melting or scattering the conductive particles, and ■ By applying this pulsed current, the conductive particles and the upper and lower Because the resin remaining near the joint between the two steel plates will thermally decompose,
Even if the joint part comes off after crimping with a crimping roll, the pressure during welding will make electrical contact again and good weldability will be obtained.Of course, the range in which the resin will thermally decompose is limited by this pulsed energization. Since this is limited to the joint and its vicinity, the adhesive strength between the upper and lower two steel plates and the intermediate layer resin and the damping properties of the resulting damping steel plate do not deteriorate.

In addition, in the present invention, the pulsed current refers to a current whose current value changes intermittently, unlike a continuous wave such as a sine wave or direct current, and as described above, the pulsed current refers to a current whose current value changes intermittently. This refers to a current pattern in which a peak current that serves as a bond with the conductive particles and a low current (which may be zero) that serves to prevent the conductive particles from melting and scattering are repeated alternately. In order to apply such a pulsed current from the energizing roll,
For example, a capacitor power supply or the like may be used, but it goes without saying that the present invention is not limited to this embodiment.

Note that the temperature of the two upper and lower steel plates when passing through this energized roll is desirably controlled to be higher than normal temperature (room temperature). The reason for this is that at high temperatures, the resin softens well, so it is possible to more stably apply a pulsed current with the current-carrying roll in a state where the two upper and lower steel plates and the conductive particles are pressed together. Note that if the temperature is too high, the resin will deteriorate, so the temperature should be selected and determined as appropriate depending on the resin used.

Furthermore, the pressure roll and the current-carrying roll may be conventionally used well-known rolls, and there is no need for any restriction.

In this way, a vibration-damping steel plate consisting of two thin steel plates bonded to the intermediate resin layer between them is manufactured by passing through the energized rolls and then being cooled.

Further, the present invention will be described in detail using Examples, but these are merely illustrative of the present invention and are not intended to limit the present invention.

(Example) The performance of a damping steel plate manufactured by the present invention (in which a pulsed current was applied from an energizing roll in the manufacturing process shown in Figure 1(a)) was compared to the conventional method (Figure 1(b)). In the manufacturing process shown, continuous current was applied from a current-carrying roll)
A comparison is shown with a damping #il plate manufactured by. Note that these manufacturing conditions are listed below.

(a) Conductive particles...average particle size: 60p (any one of stainless steel powder, Zr powder, Ni powder, iron powder) (b) Vibration damping resin...thickness: 50p (PVC, urethane powder) ,
Any one of acrylic, polyolefin, or polyester> (C) Amount of conductive particles added: 0.8 volume relative to the resin (e) (d) Coil width: 500 mm (e) Steel plate during heat compression bonding Temperature...150°C (f
) Current roll...Current: 18,000 Conducting time (pulse time): 300μs Rest time = 200μs (The above pulsed current was obtained using a capacitor power source for the pulsed current.) (g) Threading speed...・5 m/min 01) Steel plate...Thickness: 2 cold rolled steel plates with a thickness of 0.4 mm (]) Resistance weldability...The obtained damping steel plate was 30X
Cut into 30mm squares and spot weld (current: 5 100008, time: 10 cycles, pressure 200k)
gf> was carried out, and cases where current did not flow or where current flowed at a location other than directly under the electrode and a burnt mark or hole was formed on the surface of the steel plate were considered to be defective and evaluated based on the rate (n number - 1000).

The results are shown in Table 1.

Table 1 6 As shown in Table 1, it can be seen that the resistance weldability is significantly improved by the present invention.

On the other hand, it can be seen that the weldability of Sample No. 6 to Sample No. 9, which are comparative examples, is deteriorated. That is, sample No. 6 was not energized during crimping, so sample No. 7 to sample No.

In sample No. 9, pulsed current was not applied but continuous current was applied, so in sample No. 7 and sample No. 8, the conductive particles and the steel plate were not bonded, and in sample No. 9, the conductive particles were melted and scattered. It can be seen that the resistance weldability has deteriorated significantly in both cases.

Although not shown in Table 1, the present inventors have demonstrated in other examples that the resistance weldability of damping steel plates obtained with all combinations of various conductive particles and various resin films was good. It has been confirmed in

(Effects of the Invention) Since the present invention is configured as explained above, it is suitable for manufacturing home appliances, office equipment, etc. (Note) * indicates a damping steel plate with excellent resistance weldability that is outside the scope of the present invention. It has become possible to manufacture it economically, and the industrial benefits are extremely large.

[Brief explanation of drawings]

FIG. 1(a) is a schematic explanatory diagram showing an example of an apparatus used when carrying out the method for manufacturing a vibration damping mesh plate according to the present invention; FIG. 1(b) is a diagram showing a vibration damping steel plate according to the present invention. A schematic explanatory diagram showing another example of the apparatus used when carrying out the manufacturing method of A schematic explanatory diagram showing the state of current flowing through a vibration-damping steel plate having conductive particles; FIG. FIG. 5(a) and FIG. 5(b) are schematic explanatory diagrams, respectively, showing an apparatus used when carrying out a conventional method for manufacturing a damping steel plate. 9 Yu 5th concave

Claims (1)

[Claims] A method for continuously manufacturing a vibration damping steel plate consisting of two steel plates and an intermediate layer resin between which conductive particles are mixed into the intermediate layer resin, the method comprising: two steel plates and an intermediate layer resin; After or during crimping, the two steel plates and the intermediate layer resin are bonded by applying a pulsed current while pressing the two steel plates and the intermediate layer resin with an energized roll. A method for manufacturing vibration-damping steel plates.