JPH0347749A - Resistance-weldable damping steel plate - Google Patents

Abstract

PURPOSE:To contrive to stabilize high resistance-weldability without impairing the bond strength by a method wherein the ratio between the hardness of metal particle and the surface hardness of thin steel sheet is specified. CONSTITUTION:Viscoelastic polymeric resin, in which metal particles acting as electrically conductive material are uniformly dispersed, is laminated between two thin steel sheets. The preferable thickness of the viscoelastic polymeric resin layer is 10 - 150mum. As the viscoelastic polymeric resin, polyolefin, polyester or the like can be used. Material for giving electrical conductivity is one, which makes the ratio between the surface hardness (Sh) of the skin steel sheet and the hardness (Ph) of metal particle to be 0.6<=Ph/Sh<=1.1. The ratio between the metal particle diameter in the direction of the thickness of the resin film before lamination and that after lamination or flattening ratio is preferably ensured to be 20% or more. Further, the amount of biting of the metal particle into the skin steel sheet is 1% of the thickness of the resin film at the lowest and 10% as its upper limit. Furthermore, the loading of metal particle is preferably 2 - 5vol.%.

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a damping steel plate having excellent vibration damping ability,
More specifically, the present invention relates to a resistance weldable vibration-damping steel plate that has excellent adhesive strength, which influences press formability, and is particularly excellent in resistance welding performance represented by spot welding, seam welding, and projection welding. (Prior Art) In recent years, demands for quietness and quietness have increased in various fields. In particular, in fields where it is necessary to effectively suppress vibrations and noise from the outside, such as products that use prime movers such as automobiles and home appliances, or construction materials used in buildings, this vibration and noise The application of damping steel plates, which are effective in absorbing energy, is being actively promoted. Such damping steel plates use cold-rolled steel plates, various plated steel plates, stainless steel plates, aluminum plates, titanium plates, and even synthetic resin plates as the skin material, and have high viscoelasticity between these two skin plates. A so-called restraint-type composite material (vibration damping material) in which molecular resin is sandwiched is used. However, since the polymer resin sandwiched between the skin steel plates is an electrical insulator, spot welding, seam welding, which is the typical joining technology when applying thin materials to structural members, has traditionally been used. There was a drawback that welding methods such as projection welding could not be directly applied. (Problems to be Solved by the Invention) Recently, iron powder (Japanese Patent Application Laid-open No. 57-51453), nickel powder (Japanese Patent Application Laid-open No. 57-51453), and 63-188040), carbon powder (Japanese Patent Laid-Open No. 57-1
63560) and the like are becoming widely adopted. According to these methods, conductivity is imparted to the viscoelastic polymer resin, but in order to prevent welding defects during welding, it is necessary to add a large amount of conductive substance. . However, as the amount of conductive material added increases,
Although weldability can be stabilized and the incidence of welding defects can be reduced, a problem arises in that shear tensile adhesive strength also decreases ("Materials and Processes JVoQ, 1, Nci 5
Lecture number 345, [Tetsu to Hagane JVoU, 63. Na13,
(See p. 363). A decrease in adhesive strength causes the composite plate (two plates) to peel during press processing, which is a typical method for processing thin materials, and is a fatal defect that prevents molding. Furthermore, when various types of plated steel sheets are used as the skin material, it is difficult to easily stabilize weldability and completely prevent the occurrence of welding defects even if conductive substances are added. This is a major impediment to the expansion of the application of various types of plated steel sheets with excellent corrosion resistance as skin materials for damping steel sheets. The present invention was made in order to solve the problems of the above-mentioned conventional technology, and without reducing vibration damping performance,
It goes without saying that the adhesive strength required for press forming is not compromised, and even when plated steel sheets are used as the skin material,
The object of the present invention is to provide a resistance weldable vibration-damping steel plate that allows stable resistance welding. (Means for Solving the Problems) In order to achieve the above object, the present inventors first investigated in detail the causes of welding defects during resistance welding and the causes of decrease in adhesive strength. As a result, the following causes were found. In other words, the reason for the decrease in adhesive strength and the occurrence of welding defects is that the adhesion during lamination of damping steel plates is incomplete, and the conductivity-imparting substance added to the viscoelastic polymer resin does not bond with the skin steel plate after lamination. This is due to the fact that there are non-uniform parts with resin interposed (involved) in between and parts without resin. In particular, in the case of a plated steel plate with a high hardness on the surface of the skin steel plate, resin is very often present in a state where the resin is involved and interposed. If a conductive substance is present in such a state, at the initial stage of energization during resistance welding, current will flow through the energizing circuit without resin, and the resin will melt and soften due to the resistance heat generation (Joule heat) that accompanies the energization. However, the resin is removed by the pressure applied by the electrode, causing dielectric breakdown between the skin steel plate and the conductive material.
Sparks will be generated. In addition, if resin is often interposed between the skin steel plate and the conductive material,
At the initial stage of energization, current concentrates in a local area that acts as a current-carrying circuit, and if the Joule heat generated at this time significantly exceeds the heat capacity of the skin steel plate, the skin steel plate will melt and the internal resin will soften, melt, and
In some cases, the skin steel plate becomes perforated because it cannot withstand the increase in internal pressure between the steel plates due to evaporation. In order to prevent this, if the amount of conductive material added is increased, stable current-carrying circuits without intervening resin between the skin steel plates will increase, and weldability will become stable. However, as the adhesive area between the steel plate surface and the resin, which provides the original adhesive strength, decreases, the number of hydrogen bonds that contribute to the adhesive decreases, and the adhesive strength decreases. In addition, if a conductive substance with a particle size smaller than the resin film thickness is added, an effective current-carrying circuit cannot be formed even by applying pressure to the electrode, resulting in non-current-carrying and holes where welded joints cannot be obtained. It has become clear that this causes serious defects such as empty space. Therefore, in order to stabilize resistance weldability, it is desirable to add a substance larger than the thickness of the damping resin film in order to improve the electrical conductivity between the skin steel plates. When the surface steel plate is deformed, the bonding area between the skin steel plate and the damping resin decreases, and the bonding strength decreases. Furthermore, since a resin is interposed between the skin steel plate and the electrically conductive substance, resistance weldability is not always stable. Based on the results of the above cause investigation, the present inventors have developed a method for forming a current-carrying circuit that is effective during resistance welding by mixing a powdered conductive substance with a viscoelastic polymer resin, which is different from the prior art described above. As a result of research from a completely different angle, we have found that it is possible to easily stabilize extremely high resistance weldability without compromising the adhesive strength of resistance weldable damping steel plates, which was difficult with conventional technology, and to manufacture them at low cost. This is what I discovered. That is, the resistance weldable damping steel plate according to the present invention is
In a vibration-damping steel plate that is laminated by sandwiching a viscoelastic polymer resin with metal particles evenly dispersed between two thin steel plates, the hardness (Ph) of the metal particles and the surface hardness of the thin steel plate are It is characterized in that the ratio of (Sh) is in the range of 0.6≦Ph/Sh≦1.1. The present invention will be explained in more detail below. (Function) The resistance weldable damping steel plate according to the present invention has a structure in which a viscoelastic polymer resin in which metal particles that act as a conductive substance are uniformly dispersed is laminated between two thin steel plates. have. The thin steel sheet can be made of various steel types used for this type of application, such as ordinary cold rolled steel sheet, hot rolled steel sheet, various types of plated steel sheet, stainless steel sheet, etc., and is particularly suitable for various types of plated steel sheet. Also, the thickness of the plate is not particularly limited. The thickness of the viscoelastic polymer resin layer is not particularly limited, but may be 10
-150μ is preferable, more preferably 30-80μ
m range. When the resin film thickness is less than 10 μm, the damping performance of the damping resin decreases. This is not preferable because the effect of converting external vibration energy into thermal energy and dissipating it is rapidly attenuated, making it impossible for the vibration damping steel plate to exhibit its original characteristics. On the other hand, even if the resin film thickness exceeds 150 μm, the damping performance itself does not deteriorate, but due to the insufficient strength of the resin itself, the amount of deviation at the end of the steel plate becomes large during processing and forming of the damping steel plate, which is disadvantageous. It goes without saying that the viscoelastic polymer resin can be made of various materials used for this type of application, such as polyolefin, polyester, vinyl acetate, and the like. Various metal particles can be used as the conductivity imparting substance, but in the present invention, the surface hardness (Sh) of the skin steel sheet
and the hardness (Ph) of metal particles, and the range is 0.6≦Ph/Sh≦1.1. In other words, if the ratio between the hardness of the metal particles and the surface hardness of the skin steel plate is 0.6 or more, welding defects will not occur during resistance welding, but if it is less than 0.6, welding defects will not occur completely. cannot be prevented. If the ratio exceeds 1.1, there will be no problem in weldability, but a dispersion pattern of metal particles will occur on the surface of the damping steel plate, which is unfavorable from the viewpoint of surface quality. Next, the hardness of the metal particles to be added will be explained. A water atomization method is an inexpensive method for producing metal particles. When manufactured by this method, the metal is obtained by rapidly cooling it from a molten metal, so if it is atomized, a thick oxide film exists on the surface, making it difficult to use it as a conductive material. Also, because it has a rapidly cooled structure, it has very high hardness and poor ductility. In order to avoid this drawback, heat treatment is performed in a reducing atmosphere to reduce the oxide film on the surface layer, and the hardness of the metal particles (
strength) and improve ductility. By controlling the heat treatment conditions, predetermined particle hardness and deformability can be ensured. Regarding the particle size of the metal particles to be added, using the case of iron powder as an example, when using powdered metal particles, it is not possible to obtain only a certain particle size, but always within a certain range of particle sizes. It involves distribution. Therefore, JIS
It is practical to use a sieve that complies with the regulations of Z8801, and use powder that has been sieved to a size in the mesh range that is two ranks different. When manufacturing vibration-damping steel plates, a resin film is prepared by uniformly dispersing metal particles for imparting conductivity whose hardness has been adjusted in a damping resin, and this resin film is then bonded to two skin steel plates (thin steel plates). ) when sandwiching. The resin is once melted by heating, and a resin pool is created to prevent air from being drawn into the damping resin layer. After that, when laminating with a metal roll to a predetermined resin film thickness, laminating is applied with a pressure greater than the reaction force of the molten resin, so that the metal particles, which are conductive substances, are deformed to the resin film thickness. At the same time, by laminating the metal particles in a state where they are bitten into the skin steel plate, contact between the metal particles and the skin steel plate becomes very good, and resistance weldability becomes stable. In addition, the presence of metal particles embedded in the skin steel plate acts as an anchor effect on adhesive strength, and is effective in preventing a decrease in adhesive strength when the amount of conductive material added is increased. (first
(see figure). In order for both the skin steel plate and the metal particles to deform and exhibit an anchor effect, the hardness of the added metal particles must maintain a certain relationship with the hardness of the skin steel plate surface layer that is in direct contact with the metal particles. The particle size ratio of the metal particles in the resin film thickness direction before and after lamination, that is, the amount of deformation (oblateness)
It is preferable to secure at least 6% or more, preferably 20% or more. Note that there is no particular upper limit to the amount of deformation of the metal particles, but if we consider the situation where metal particles with a hardness of 1 particle size within the commonly used range are laminated to a common resin thickness, This is not done in more than 90% of cases. In addition, in order to ensure the anchoring effect of metal particles on adhesive strength, the amount of metal particles biting into the skin steel plate after lamination (δ) should be at least 1% or more of the resin film thickness (1). effective. However, it is difficult to laminate with 10% or more of the metal particles biting into the surface steel plate, and in order to make the metal particles bite into the skin steel plate to a large extent, it is necessary to make the hardness of the metal particles unnecessarily high. It also has a negative effect on the surface condition. Therefore, it is preferable to set the upper limit to 10%. Note that the amount of metal particles added should be at least the minimum amount necessary for stable weldability; adding less than 2% by volume will not prevent welding defects, and will affect vibration damping performance and adhesive strength. Within the range without influence, the maximum value is 5% by volume, and 2-5% by volume
is desirable. Also, if the ratio of the average particle diameter (d) to the damping resin film thickness (1) is 1.2 or more, no spot welding defects will be observed; if the value of d/ is 2.5 or more, , the shear adhesive strength decreases somewhat significantly. Therefore, the upper limit of the value of d/ is preferably 2.5. (Example) Next, an example of the present invention will be shown. A continuous cast aluminum killed steel sheet with a thickness of 0.4 m1 nt and a double-sided alloyed hot-dip galvanized steel sheet (coating weight: 45 g/
m2), and a polyolefin resin in which metal particles were uniformly dispersed in advance was laminated therebetween. A test piece was taken from this laminated steel plate and an accuracy test was conducted. Note that the lamination conditions are as follows. ■Conductivity imparting substance: (1) Pure iron powder manufactured by water atomization method, hardness Hv
(0,005) = 110 (2) Low alloy steel powder manufactured by water atomization method, hardness Hv (0, 0O5) = 173 (3) Pure Ni powder manufactured by water atomization method, hardness Hv (0, 005)=122 (4) Pure Ni powder produced by gas reduction method, hardness Hv
(0,005) = 252 (5) 5US304 powder manufactured by water atomization method, hardness Hv (0,005) = 220 (6) 5US304 powder manufactured by water atomization method, hardness Hv (0,005
)=480 ■Gold metal particle/particle size: 63~87μ side ■Metal particle addition amount: 3.5% by volume (constant) ■Laminating resin film thickness: 50μ ugly (±3μn+) ■Skinned steel plate surface layer (plating layer ) Hardness Hv (0,001) = 265 From the prototype laminated steel plate, the test piece size was 30m++
Cut into the shape of +w x 100++usQ, 1000
A sample was taken. Using this sample, spot welding was performed with an overlap distance of 30+ m, and spot weldability was evaluated. The results are shown in Table 1. The welding conditions were: electrode pressure of 200 kgf, welding current of 8 kA, and energization time of 12 cycles. Spot weldability was determined by observing the surface condition of the spot welding specimen after welding.
The incidence of welding defects such as holes, burns, and non-energization on the surface of the steel plate was totaled, and the rate of occurrence of welding defects was calculated based on the ratio of the number of sheets tested for welding. From Table 1, it can be seen that the invention examples &2. It can be seen that all of NQ4 to Nα5 have excellent spot weldability and good surface conditions.

[Left below]

11 Continuously cast aluminum killed steel plate with plate thickness 0, 4 mm, and Z
n-Ni alloy double-sided electroplated steel sheet (plating weight: 20
g/[11"), and a polyolefin resin in which metal particles were uniformly dispersed in advance was laminated between them. A test piece was taken from this laminated steel plate and an accuracy test was conducted. The lamination conditions were as follows. They are as follows. ■Conductivity imparting substance: (1) Pure iron powder manufactured by water atomization method. Hardness Hv (0,005)" 110 (2) Low alloy steel powder manufactured by water atomization method , hardness Hv (0,005) = 173 (3) Pure Ni powder manufactured by water atomization method. Hardness Hv (0,005) = 122 (4) Pure Ni powder manufactured by gas reduction method, hardness Hv
(0,005) = 252 (5) 5US304 powder manufactured by water atomization method, hardness Hv (0,005)” 220 (6) 5US304 powder manufactured by water atomization method, hardness Hv (0,00
5) = 480 ■Gold metal particles/particle size: 63 to 87 μm ■Amount of metal particles added: 3.5% by volume (constant) ■Laminating resin film thickness 850 μm (±3 μm) ■Surface steel plate surface layer (
Hardness of plating layer) Hv (0,001) = 265 From the prototype laminated steel plate, test piece size 30n+m
It was cut into a shape of w x 100 m + ul, and 1000 samples were collected. Using this sample, overlap thickness is 30
Spot welding was performed with a diameter of 1 mm, and the spot weldability was evaluated. The results are shown in Table 2. In addition. Welding conditions and evaluation of spot weldability were the same as in Example 1. From Table 2, inventive examples Nα4 to No. 5 in which the ratio of the hardness (Ph) of the metal particles to the surface hardness (Sh) of the thin steel plate is in the range of 0.6≦Ph/Sh≦1.1, It can be seen that both have excellent spot weldability and good surface conditions.

[Left below]

Continuously cast aluminum killed steel sheet with thickness 0,4 ma+t and steel sheet with Fe-Zn alloy electroplated on the surface of 1-alloyed hot-dip galvanized steel sheet (the coating weight is 4 mm).
0 g/m" and electroplating of 5 g/m"), and between them, a polyolefin resin in which metal particles had been uniformly dispersed was laminated. A test piece was taken from this laminated steel plate and an accuracy test was conducted. Note that the lamination conditions are as follows. ■Conductivity imparting substance: (1) Pure iron powder manufactured by water atomization method, hardness Hv
(0,005) = 110 (2) Low alloy steel powder manufactured by water atomization method, hardness Hv
(0,005) = 173 (3) Pure Ni powder manufactured by water atomization method, hardness Hv
(0,005) = 122 (4) Pure Ni powder produced by gas reduction method, hardness Hv
(0,005) = 252 (5) 5US304 powder manufactured by water atomization method, hardness Hv (0,005) = 220 (6) 5US304 powder manufactured by water atomization method, hardness Hv (0,005
) = 480■Gold metal particles/particle size: 63~87μm ■Amount of metal particles added: 3.5% by volume (constant) ■Lamination resin film thickness 850μm (±3μm) ■Skinned steel plate surface layer (
Hardness of plating layer) Hv (0,001) = 265 From the prototype laminated steel plate, test piece size 30 mmw
It was cut into a shape of x 100mmQ and 1000 samples were collected. Using this sample, one overlap is 30mm.
Spot welding was performed using the following method, and spot weldability was evaluated. The results are shown in Table 3. In addition. Welding conditions and spot weldability are the same as in Example 1. From Table 3, inventive examples N [14 to Nc15 are It can be seen that both have excellent spot weldability and good surface conditions. (Effects of the Invention) As detailed above, according to the present invention, various plated steel sheets can be used as the skin material without reducing vibration damping performance and without impairing the adhesive strength required for press forming. However, it is possible to provide a resistance weldable damping steel plate with excellent performance that allows stable resistance welding.

[Brief explanation of drawings]

FIG. 1 is a diagram illustrating the anchor effect that prevents a decrease in adhesive strength.

Claims (1)

[Claims] (1) In a vibration-damping steel plate laminated with a viscoelastic polymer resin in which metal particles are uniformly dispersed between two thin steel plates, the hardness of the metal particles ( A resistance weldable damping steel plate, characterized in that the ratio of the surface hardness (Sh) of the thin steel plate to the surface hardness (Sh) of the thin steel plate is in the range of 0.6≦Ph/Sh≦1.1. (2) The damping steel plate according to claim 1, wherein the metal particles have an oblateness ratio of 20% or more after lamination. (3) Claim 1, wherein the ratio between the amount of metal particles biting into the skin steel plate (δ) after lamination and the thickness (t) of the viscoelastic polymer resin film is in the range of 1%≦δ/t≦10%. Or the damping steel plate according to 2. (4) The amount of metal particles added to the viscoelastic polymer resin is 2 to 5
The vibration damping steel plate according to claim 1, which is % by volume.