JPH02286505A - Conveyor belt - Google Patents

Abstract

PURPOSE:To suppress the occurrence of a warp by setting the tensile elastic modulus of the resin constituting each layer higher in the order of a core layer, a surface layer and a back layer in a three-layer constitution conveyor belt made of thermoplastic resin. CONSTITUTION:The tensile elastic modulus of the resin constituting each layer, e.g., polyester elastomer, is set higher in the order of a core layer 2, a surface layer 1 and a back layer 3. The ratio of the tensile elastic modulus between the surface layer 1 and the back layer 3 is set to 1.1-5.1. The occurrence of a warp can be suppressed according to this constitution.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a conveyor belt constructed from thermoplastic resin.

[Prior art] Nbare belt is made of polyvinyl chloride, polyvinyl chloride,
Those manufactured by coating thermoplastic polyurethane, ionomer resin, etc. by calendering, those manufactured by applying adhesive treatment to the base fabric and adhering it to a resin sheet under hot pressure, or when extruding a resin sheet, Products manufactured by thermocompression bonding with base fabric are often used. Although these belts have excellent strength, the base fabric is highly absorbent and the surface of the base fabric is uneven, making it easy for mold and bacteria to propagate. There is a problem that it is difficult to remove oil, fat and dust. Furthermore, when the belt meanderes while being driven, the resin layer on the surface is peeled off by the guide, exposing the base fabric and fluffing the edges, resulting in dust. These problems become fatal when the belt is used for conveying food or precision equipment.

On the other hand, a single-layer extruded polypropylene sheet or polyester elastomer sheet may be used as a conhair belt. In this case, since the surface is smooth, it is difficult for dirt and germs to adhere to it.

In addition, fuzzing, which occurs when a base fabric is used, is also suppressed.

Problems to be Solved by the Invention However, if the conveyor belt using the single-layer resin sheet described above continues to be used, it will warp in the width direction with the front surface becoming concave. When the conveyed object on the conveyor is detected by a phototube or the like, the warpage causes the side edges of the conveyor to rise up, making it difficult to detect the conveyed object.

An object of the present invention is to suppress the occurrence of warpage in a conveyor heald made of thermoplastic resin.

Means for Solving the Problems In other words, the conveyor belt according to the present invention has three thermoplastic resin layers integrated into one, a surface layer 1, a core layer 2, and a back layer 3, as shown in FIG. . The tensile modulus of the resin constituting each layer is increased in the order of core layer, surface layer, and back layer.

The ratio of tensile modulus of the surface layer/back layer is preferably 1.
1 to 5.1.

We investigated the mechanism by which warpage occurs in a conveyor belt using a single-layer resin sheet, and found the following.

When the belt is being driven by the pulley 4, especially just before the belt runs along the circumferential surface of the pulley 4, due to the thickness of the belt, there is a difference between the tensile stress 5 on the front side of the belt and the tensile stress 6 on the back side of the belt. It makes a difference. When the belt is placed along the pulley 4, the front side of the belt becomes the outer peripheral surface and is pulled more than the back side of the belt, so the tensile stress 5 becomes the tensile stress 6.
It's bigger.

The tension in the heddle driving direction appears as contraction in the belt width direction. Then, depending on the amount of elongation in the belt drive direction based on the tensile stress on the front and back surfaces, there is a difference in the amount of shrinkage in the width direction between the front and back surfaces, and as shown in Figure 2, the width of the front side is concave. This causes a warpage in the direction. If you want to reduce the diameter of the pulley 4, you must reduce the tensile elastic modulus of the belt to make the belt follow the pulley well, so the belt tends to stretch more easily due to tension, and the warpage becomes even greater. .

From the above findings, in the conveyor belt according to the present invention, the tensile modulus of the surface layer is made larger than the tensile modulus of the back layer, so the difference in elongation of the belt due to the difference in tensile stress between the front and back surfaces is It becomes smaller on the back side and suppresses warpage in the belt width direction. A resin layer with the highest tensile elastic modulus is placed in the core layer of the belt to improve the belt's creep resistance, but the material of the core layer is The material of the layer and back layer does not affect the quality of the material, and it can also be used as a conveyor belt for those with small pulley diameters.

Example Next, examples of the present invention will be described together with comparative examples.

A three-layer sheet was extruded using a combination of thermoplastic polyester elastomer resins having various tensile moduli shown in Table 1, with a thickness configuration of surface layer/core layer/back layer = 0.5310.5510.53 mm. .

This was processed into a conveyor belt with a width of 200 mm and a length of 5 m so that the side with a higher tensile elastic modulus was the surface layer.

The mounting test of the conveyor belt was carried out under the following running conditions, and the results of measuring the amount of warpage h (see FIG. 3) after the test are also shown in Table 1.

Running conditions Pulley diameter: 150 mm Tension: 4% Running speed: 10 m/min Weight of conveyed object: 3 kgf Running time: 48 hours The resin types in Table 1 are as follows.

A: Product name Belprene P 150B manufactured by Toyobo B
:Product name Belprene E 450B Same as above C:Product name Belprene P 90BD Same as above D=A above
Blend product of and C Same as above E: Product name Perbrene P
150BGF10 (contains 10% by weight of glass fibers) It can be seen that it is possible to suppress the elasticity, but from Example 1.2.4, the ratio of the tensile modulus of the surface layer/back layer is 1.1 to 5.
It can be seen that a value in the range of 1 is even better.

The tensile modulus of the core layer is set to the largest value among the three layers, but the set value may be determined as appropriate depending on the application, such as the tension applied to the belt and the load of the conveyed object. In addition, warping of the belt, which forms the surface layer, makes it easier for conveyed objects to slip off due to vibrations, etc.
In some cases, it is better to reduce the tolerance range.

Effects of the Invention As described above, the thermoplastic resin conhair belt according to the present invention has a surface layer, a core layer, and a back layer with different tensile moduli, so that warping in the width direction is small and the belt is resistant to warping. Creep properties can also be maintained.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing a conveyor belt according to the present invention together with its cross section, Fig. 2 is a cross-sectional explanatory diagram showing a situation in which warpage occurs in the belt, and Fig. 3 shows a state in which warpage of the belt is measured. FIG. 1 is the surface layer, 2 is the core layer, 3 is the back layer box diagram

Claims (1)

[Claims] 1. A conveyor belt in which three thermoplastic resin layers, a surface layer, a core layer, and a back layer, are integrated, and the tensile modulus of the resin constituting each layer is different from that of the core layer and the surface layer. A conveyor belt characterized by a layer and a back layer that are higher in order. 2. The ratio of the tensile modulus of the surface layer/back layer is 1.1 to 5.
1. The conveyor belt according to claim 1.