JPH1120039A - Tubular body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a member which sufficiently secures bonding strength between an FRP tubular body and a metal member and has a small decrease in bonding strength even when subjected to a heat history such as rubber vulcanization. SOLUTION: The coefficient of linear expansion in the circumferential direction of the inner peripheral surface of the fiber-reinforced plastic cylindrical body is 8 × 10 ⁻⁶ / ° C. to 15 × 10 ⁻⁶ /.
A cylindrical body having a temperature range of ° C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylindrical body having a light weight and a high rigidity, and particularly to a roll or a core used for film and paper production, processing equipment and a printing machine, or a truss structural member or a drive shaft. It relates to a suitable cylindrical body.

[0002]

2. Description of the Related Art Conventionally, rolls and cores used in film and paper manufacturing, processing equipment and printing machines, and tubular members such as truss structural members and drive shafts are often made of metal such as iron or aluminum alloy. Has been used. However, recently, a tubular member made of fiber reinforced plastic (FRP), which is lightweight and has a high specific modulus, has been used. This is because the characteristics of the FRP are effective not only in reducing maintenance work but also in improving production speed and product quality.

[0003] A cylindrical member made of FRP is usually used by joining metal members to both ends. This metal member
In rolls, it is used to attach bearings,
The core is used for meshing with a driving device, and the truss member and the driving shaft are used for joining with related parts.
Adhesive joining is the most common method of joining FRP and metal because welding is impossible, as is the case with metals, and the joining strength with pins, rivets, screws, etc. is low.

In general, FRP and metal have different coefficients of linear expansion, so that a tubular body composed of a FRP tubular member and a metal member as described above often cannot provide sufficient adhesive strength. Specifically, while the linear expansion coefficient of iron is 11 × 10 ⁻⁶ / ° C., the linear expansion coefficient of the conventional FRP tubular member in the circumferential direction is smaller than that of an iron mandrel usually used during molding. In order to make it easy to pull out, it is set to 4 to 7 × 10 ⁻⁶ / ° C., which is smaller than the linear expansion coefficient of iron. Furthermore, FR
In the case of P, the actual amount of change in the inner diameter of the pipe tends to be smaller than the amount of change in the inner diameter of the pipe estimated from the theoretical linear expansion coefficient calculated in the circumferential direction. This is because the coefficient of linear expansion of FRP is generally anisotropic, and the coefficient of linear expansion in the thickness direction of FRP is larger than that in the circumferential direction. I was When such a tubular body and a metal member are exposed to a high temperature, that is, when a roll, a drive shaft, and a truss member are heated to cure an adhesive, rubber vulcanized, and baked, etc. Then, the inner metal member thermally expands and pushes and expands the FRP tubular body. At this time, the FRP tubular body is heated at a high temperature (for example, 120 to 1).
(50 ° C.), the elastic modulus in the thickness direction is low, so that it easily creeps. Residual stress is generated, and the bonding strength is reduced.

On the other hand, Japanese Patent Application Laid-Open No. 4-107309 proposes to use a low thermal expansion metal shaft to reduce the difference in linear expansion coefficient and increase the adhesive strength under high temperature conditions. I have. However, low thermal expansion metals are extremely expensive and difficult to use for general industrial parts.
In addition, since the coefficient of linear expansion varies depending on the temperature range, FR
It was difficult to match the coefficient of linear expansion of P.

[0006]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the conventional FRP cylindrical body, and can secure a sufficient adhesive strength to metal parts, and can provide an inexpensive FRP cylindrical body. Is to provide the body.

[0007]

In order to solve the above-mentioned problems, a cylindrical body according to the present invention has a coefficient of linear expansion in the circumferential direction of an inner peripheral surface of a fiber-reinforced plastic cylindrical body of 8 × 10 ⁻⁶ /. ℃ -1
It is characterized by being in the range of 5 × 10 ⁻⁶ / ° C.

[0008] The tubular body according to the present invention, in the tubular body made of fiber reinforced plastic, includes a layer in which the orientation angle of the reinforcing fibers is in the range of ± 75 ° to 90 ° with respect to the axial direction, and The ratio of the thickness of the layer to the total thickness, the elastic modulus of the reinforcing fibers used in the layer, and the circumferential stiffness coefficient which is the product of the volume fiber content is in the range of 6 to 25 GPa. What you do.

Further, the roll according to the present invention comprises a layer in which the orientation angle of the reinforcing fibers is in a range of ± 75 ° to 90 ° with respect to the axial direction in the fiber-reinforced plastic tubular body,
And a cylindrical shape having a circumferential stiffness coefficient which is a product of a ratio of a thickness of the layer to a total thickness, an elastic modulus of a reinforcing fiber used for the layer, and a volume fiber content in a range of 6 to 25 GPa. A steel shaft is attached to both ends of the body.

In such a cylindrical body, the coefficient of linear expansion of the inner peripheral surface in the circumferential direction is 8 × 10 ⁻⁶ / ° C. to 15 × 10 ^−6.
/ ° C is adjusted to a value equal to or close to the linear expansion coefficient of metal, especially steel, so that there is no difference or extremely small difference in the amount of thermal expansion when bonding the two, and high bonding strength can be obtained. .

The desirable coefficient of circumferential linear expansion of the inner peripheral surface of the FRP tubular body controls a characteristic relating to the circumferential rigidity of the FRP tubular body expressed as a product of the above three characteristic values. , Whereby a high bond strength is obtained.

[0012] Therefore, by setting the FRP cylindrical body side to the characteristics within the optimum range, it is possible to achieve high adhesive strength to a normal steel shaft without using an expensive low thermal expansion metal shaft. This makes it possible to manufacture desired rolls and the like at low cost.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below. In the present invention, as the reinforcing fibers of the FRP tubular body, it is preferable to mainly use carbon fibers so as to obtain a lightweight and highly rigid tubular body, but other reinforcing fibers may be used, Two or more types of reinforcing fibers may be used in combination. ± 75 ° to 90 with respect to the axial direction
° When two or more types of reinforcing fibers having different elastic moduli are used in the layer, the circumferential stiffness coefficient is calculated separately,
Just add them up.

The matrix resin is preferably an epoxy resin, but a phenol resin, a vinyl ester resin, an unsaturated polyester resin or the like may be used from the viewpoint of cost and corrosion resistance.

The volume fiber content must be set as high as possible without impairing the impregnation in order to sufficiently exhibit the performance of the cylindrical body, and may be set in the range of 45% to 70%. preferable.

Regarding the lamination structure, rolls, long cores,
When it is necessary to attach importance to the axial strength, elastic modulus, and natural frequency of truss members, etc., 0 ° to ± 2
It is preferable that the layer of 0 ° is contained by 80% or more. When the torque is large, such as in a drive shaft, it is necessary to increase the number of ± 45 ° layers.

A circumferential component of ± 75 ° to 90 ° with respect to the axial direction is necessary for improving buckling strength and machinability.
It is also closely related to the coefficient of linear expansion in the circumferential direction. That is,
The ratio of the thickness of the layer to be ± 75 ° to 90 ° with respect to the axial direction with respect to the total thickness, the elastic modulus of the reinforcing fiber used for the layer,
And the volume fiber content is closely related to the coefficient of linear expansion in the circumferential direction, and when the circumferential stiffness coefficient, which is the product of these three values, is in the range of 6 to 25 GPa, the inner circumferential surface of the FRP tubular body Has a coefficient of linear expansion in the circumferential direction of 8 × 10 ⁻⁶ / ° C. to 15 × 1
0 ^-6 / ° C. The coefficient of linear expansion of the inner peripheral surface in the circumferential direction here is a rate of change of the inner diameter of the cylindrical body due to a temperature change, and is different from a value calculated from the laminated plate theory. The circumferential linear expansion coefficient calculated from the laminated plate theory is the rate of change of the average diameter at the center of thickness of the cylindrical body, and the rate of change of the inner diameter of the cylindrical body is larger than the rate of change of the average diameter. The rate of change of the outer diameter of the cylindrical body is smaller than the rate of change of the average diameter. This is because the coefficient of linear expansion in the thickness direction of the cylindrical body is larger than that in the circumferential direction.

When metal shafts are attached to both ends of the cylindrical body, the material is most preferably low alloy steel such as carbon steel or chromium molybdenum steel in view of strength, rigidity and cost. Aluminum and stainless steel are sometimes used from the viewpoint of weight reduction and corrosion resistance. However, since these materials have a large linear expansion coefficient of 19 to 24 × 10 ⁻⁶ / ° C., the linear expansion coefficient of the outer periphery of the shaft body is 15 × 10 6. It may be used in combination with carbon steel or low-alloy steel by shrink fitting so that the temperature is ^-6 / ° C or less.

As described above, the FRP tubular body of the present invention is:
Since the coefficient of linear expansion at the inner diameter portion is substantially equal to that of carbon steel or low alloy steel, thermal stress is less generated at the time of heating and creep deformation does not occur, so that a member having excellent bonding strength and high reliability can be obtained. Since special materials such as low expansion metals are not used, they are inexpensive and can be mass-produced industrially.

The range of application of the linear expansion coefficient of the inner diameter, which is difficult to estimate because the linear expansion coefficient in the thickness direction is affected, is
It can be easily estimated and controlled only from the laminated structure of the RP, the elastic modulus of the reinforcing fiber, and the fiber content.

[0021]

EXAMPLES The present invention will be specifically described below based on examples and comparative examples. Examples 1 to 6, Comparative Examples 1 to 4 A cylindrical body made of CFRP (carbon fiber reinforced plastic) was formed by a filament winding method. While aligning 20 carbon fibers and impregnating the epoxy resin, a mandrel with a diameter of 80 mm is placed ± 10 ° with respect to the axial direction.
After alternately winding at an angle of ± 80 °, the epoxy resin was cured by heating at 100 ° C for 2 hours and at 180 ° C for 6 hours while rotating. Pull out the mandrel after curing,
98mm outside diameter, 80mm inside diameter, 1000m length on lathe
m to obtain a CFRP cylindrical body. At this time, as shown in Table 1, the elastic modulus of the carbon fiber was 436 GPa.
Or 230 GPa, the ratio to the thickness of the ± 85 ° layer is 0.05, 0.1, 0.15, 0.2 (0 in Comparative Example 4), and the volume fiber content is 55%, 65% (Comparative Example 4). 0.60%). The cylindrical body was heated to 150 ° C. to measure the outer diameter and the inner diameter, and the difference between the outer diameter and the inner diameter at normal temperature (20 ° C.) was examined and converted into the circumferential linear expansion coefficient.

Further, the outer diameter is 80 m using carbon steel (S45C).
m, 10 mm thick, 80 mm long pipe, and apply a one-part heat-curable epoxy adhesive
It was inserted into a cylindrical body and heated and cured at 120 ° C. for 3 hours to produce an adhesion test member. 8 at 150 ° C
After repeating the heat treatment for 10 times, a destructive test was performed using a universal testing machine. Table 1 summarizes the results of these experiments.

From Table 1, it can be seen that there is a close relationship between the circumferential stiffness coefficient and the linear expansion coefficient of the inner circumferential surface. The breaking load of the adhesion test is higher as the coefficient of linear expansion of the inner peripheral surface of the cylindrical body made of CFRP is closer to the linear expansion coefficient of steel, ie, 11 × 10 ⁻⁶ / ° C., and decreases when it is less than 8 × 10 ⁻⁶ / ° C. Begin to.
On the other hand, when the temperature exceeds 15 × 10 ⁻⁶ / ° C., the CFRP cylindrical body expands too much more than the shaft when heated, so that separation occurs between the CFRP cylindrical body and the shaft. The bond strength was extremely reduced.

[0024]

[Table 1]

[0025]

According to the tubular body of the present invention, the coefficient of linear expansion in the circumferential direction of the inner peripheral surface of the tubular body made of fiber reinforced plastic is 8%.
It is in the range of × 10 ^-6 / ° C to 15 × 10 ^-6 / ° C, and is approximately equal to the linear expansion coefficient of carbon steel or low alloy steel. FRP caused by thermal stress generated at the joint with the member
Deterioration of the joint due to creep of the pipe is eliminated, and a highly reliable member having excellent joint strength can be obtained. Therefore, high joining strength can be obtained even in a cylindrical member such as a rubber-coated roll that receives a thermal history such as rubber vulcanization. Further, the applicable range of the linear expansion coefficient of the inner diameter, which is difficult to estimate because of the influence of the linear expansion coefficient in the thickness direction, can be easily estimated from the circumferential stiffness coefficient and can be controlled to a desired range.

Claims (3)

[Claims] C. 1. The coefficient of linear expansion in the circumferential direction of the inner peripheral surface of the fiber-reinforced plastic cylindrical body is 8.times.10.sup.- ⁶ / .degree. C. to 15.times.10.sup.- ⁶ /.
A cylindrical body having a temperature range of ° C. 2. The fiber-reinforced plastic tubular body, wherein the orientation angle of the reinforcing fiber is ± 75 ° to 90 ° with respect to the axial direction.
° including a layer, and the ratio of the thickness of the layer to the total thickness, the elastic modulus of the reinforcing fibers used in the layer,
The circumferential stiffness coefficient, which is the product of the volume fiber content, is 6 to 25.
A cylindrical body characterized by being in the GPa range. 3. The fiber-reinforced plastic tubular body, wherein the orientation angle of the reinforcing fibers is ± 75 ° to 90 ° with respect to the axial direction.
° including a layer, and the ratio of the thickness of the layer to the total thickness, the elastic modulus of the reinforcing fibers used in the layer,
The circumferential stiffness coefficient, which is the product of the volume fiber content, is 6 to 25.
A roll characterized in that steel shafts are attached to both ends of a cylindrical body having a GPa range.