JPH064450B2 - Flat belt - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a flat belt used for a belt conveyor for light transportation such as food transportation.

[Prior Art] A flat belt is generally used as a conveyor belt used for a light-conveying belt conveyor for conveying food and the like.

The flat belt is formed by forming a thermoplastic resin layer on a core body such as polyester canvas.

In order to carry foods and other objects on the belt and convey them, it is essential that the belt conveyor be running stably. Therefore, conventionally, by performing crown processing on the pulley to generate a crown effect and by not causing a tension difference between the left and right in the longitudinal direction of the belt, the conveyor belt is biased or oscillated to the left or right (meander). To prevent.

The term "crown of the pulley" means that the body of the pulley has a drum-like curved surface, or that both ends of the pulley have tapered portions. The height d shown in FIG. 3 is called the crown height.

The reason why the traveling of the conveyor belt is stabilized by forming the crown on the pulley is as follows.

By adjusting the distance between the pulleys, tension acts on the flat belt (9), and the flat belt (11) is pressed against the body of the crown pulley (5) as shown in FIG.

At this time, the reaction force a _{1 of the} tension acting on the left and right of the flat belt (9),
The a ₂ is divided into component forces b ₁ and b ₂ in the pulley surface direction and component forces c ₁ and c ₂ perpendicular to the pulley surface. Then, b ₁ and b ₂ are forces that bring the flat belt (9) to the center, and when the two forces are balanced, the flat belt (9) is held at that position, and the flat belt (9) runs stably.
This is called a crown effect, and the greater the tension of the flat belt (9) or the higher the crown height, the more remarkable the effect. Then, in order to balance b ₁ and b ₂ , the traveling adjustment of the pulley is necessary.

Further, the difference in tension between the belts on the left and right in the longitudinal direction is due to the difference in strain amount between the left and right belts.
Hooke's law is applied to the tension and the amount of strain of the running belt, and the following equation holds.

σ = E · ε σ: stress (corresponding to the reaction force of tension) E: modulus ε: strain amount Tension σ is proportional to the strain amount. Since the running belt has different left and right strain amounts, the left and right stresses σ, and therefore the left and right tension reaction forces a ₁ and a _2, also differ. As a result, a ₁ , a ₂
The values of b ₁ and b ₂ which are the component forces of are also different, and the belt is biased to the smaller one of them. Therefore, it is necessary to improve the belt and make adjustments before running.

[Problems to be Solved by the Invention] In the crown pulley (5), tension is applied in the longitudinal direction in order to exert the crown effect on the flat belt (9). However, the reaction force a ₁ , a ₂ of the tension is not applied. The component forces b ₁ and b ₂ are forces that move the flat belt to the center (force in the width direction).

Further, not only the crown pulley (5) but also a general pulley such as a flat pulley applies tension to the belt in order to transmit power. A force in the width direction also acts on the belt due to this tension. If these forces in the width direction of the belt become too large, the bending rigidity in the width direction of the belt will be exceeded, and as a result, vertical wrinkling will occur.

Therefore, in the conventional flat belt, a polyester monofilament yarn or the like is used as the weft yarn of the core to increase the bending rigidity in the width direction and limit the crown height of the pulley.

This vertical wrinkle phenomenon was particularly prominent in a belt having a wide belt width and a short belt length (Fig. 5). This is because even if the belt is closely attached to the pulleys having the same crown height, the larger the belt length, the larger the tension must be applied. For example, assuming a conveyor in which the length difference between the top and both ends of the pulley in the longitudinal direction of the belt is 10 mm, if the belt length is 10 m, then 10 × 100/10 × 10 ³ = 0.1%
The belt and the pulley are in close contact with each other when stretched, whereas when the belt length is 1 m, 10 × 100/1 × 10 ³ = 1% does not come into contact unless stretched. Therefore, the tension applied to the belt increases accordingly. As a result, the force in the belt width direction is also increased, and vertical wrinkles are likely to occur.

Here, the flexural rigidity means the modulus E of the belt and the cross section 2
It is represented by the product of the second moments I. By the way, when the bending stiffnesses EI of two belts are compared, if the dimensions of the belts as samples are made the same, the second moment of inertia I becomes the same, so that the bending stiffness EI becomes a function of the modulus E in the end.

Regarding bending rigidity, the following formula is established.

From this equation, when the bending rigidity EI is large, the curvature radius R of the belt becomes small, which means that the belt is hard to bend.

When a flat belt having bending rigidity in the width direction is mounted on the crown pulley (5) as shown in FIG. 3, a part of the top of the pulley comes into contact. Therefore, in order to bring the flat belt (9) into close contact with the body of the crown pulley (5), tension must be applied to the flat belt (9) in the longitudinal direction of the belt and strongly pressed against the body.

However, since the conventional flat belt made of polyester canvas or the like has a large bending rigidity in the longitudinal direction of the belt as described above, a large tension is required to bring it into close contact with the pulley.

As a result, the component component of the tension generated in the width direction is increased, and vertical wrinkles are generated. Further, the higher the crown height, the more tension needs to be applied, so there is a limit to the crown height.

In the flat belt, the magnitude of the flexural rigidity EI in the belt longitudinal direction is derived from the modulus E.

That is, when the modulus E is large, the stress σ, and thus the tension reaction forces a ₁ and a ₂ also increase. Therefore, even if the difference between the left and right strain amounts is small, it is amplified by the modulus E and the reaction force difference between the left and right belt tensions becomes significant.

Since the conventional flat belt has a large modulus E in the longitudinal direction, the difference between the reaction forces a ₁ and a ₂ of the left and right tensions is large. Therefore, the running of the belt was unstable and it took a long time to adjust the belt.

Such a problem was conspicuous when the belt width was wide and the belt length was short, or when several narrow belts were used in parallel as shown in FIG.

In the case of the former, the deviation of the belt is likely to occur,
This is due to the high crown height.

In the latter case, the reason is that the adjustment pulley for stabilizing the running of the belt cannot be attached because the gap between the pulleys is small. Adjacent belts contact each other and become very unstable, and even if an adjustment pulley was attached, the running adjustment of the belt had to be performed for each forward and reverse rotation.

Regarding the modulus and bending rigidity of the conventional flat belt,
The ratio between the belt longitudinal direction and the belt width direction is illustrated below.

Modulus: Belt length direction is 30 to 150 in the belt width direction
% Flexural rigidity: The longitudinal direction of the belt is 30 to 350% in the width direction of the belt. Therefore, the present invention can be used for pulleys with high crown height, and can be stably run even if there is a difference in the amount of strain on the left and right sides of the belt. The purpose is to provide a belt.

[Means for solving problems]

According to the present invention, the presence or absence of vertical wrinkling of a belt hung on a crown pulley, and the quality of running stability due to the difference in strain amount between the right and left sides of the belt determine the modulus of the belt, more specifically, the longitudinal direction and the width direction of the belt. Focusing on the fact that it is controlled by the modulus ratio, a flat belt is composed of a thermoplastic resin layer and a core, and the core has a warp yarn in the belt longitudinal direction and a weft yarn in the belt width direction, and the modulus in the belt longitudinal direction is the belt. It is set to 3.25 to 15% of the modulus in the width direction.

[Action]

In the present invention, the modulus in the longitudinal direction is set to 3.25 to 15% of the modulus in the width direction, which is much smaller than the conventional one. This has the following two effects.

It becomes relatively easier to stretch in the belt longitudinal direction than in the belt width direction, and vertical wrinkles do not occur even when the flat belt is greatly stretched and attached in the belt longitudinal direction.

That is, since the modulus of the woven yarn (warp yarn in the present invention) in the longitudinal direction is small, the tension generated is small even when the belt is greatly stretched. Therefore, the component forces b ₁ and b ₂ generated by the crown effect and the force in the width direction due to the tension of power transmission are also reduced, and vertical wrinkles of the belt are less likely to occur.

In this case, if it exceeds 15%, vertical wrinkles will occur, and if it is less than 3.25%, the power transmission force of the belt will be adversely affected.

When the modulus in the belt width direction is set to the same value as that of the conventional flat belt, the modulus in the belt longitudinal direction is significantly reduced as compared with the conventional one.

Therefore, according to Hooke's law, if the modulus E decreases, the stress σ also decreases. This means that as the modulus E in the longitudinal direction decreases, the absolute values of the reaction forces a ₁ and a ₂ of the tension on the left and right of the belt also decrease, and the difference in the strain amount on the left and right of the belt has no effect on the difference in tension. Get smaller.

In this case, when the modulus in the longitudinal direction of the belt exceeds 15%, the difference in tension due to the difference in strain amount starts to affect the running of the belt such as the deviation of the belt and the lateral swing. on the other hand,
If it is less than 3.25%, the power transmission force becomes insufficient as described above.

[Embodiment] An embodiment of the present invention will be described with reference to the drawings.

1 and 2 show a concrete embodiment of the flat belt according to the present invention. The flat belt of FIG. 1 is a one-ply product in which a synthetic resin layer (2) is formed on the core body (1). The flat belt of FIG. 2 is a two-ply product in which two one-ply products are stacked.

The synthetic resin layer (2) is made of polyurethane resin, vinyl chloride resin, polyester resin or the like, and is formed on the core body (1) by means of coating, adhesion with an adhesive, vulcanization adhesion or the like. In the case of coating, a synthetic resin may be impregnated into the core body (1).

The core body (1) is a canvas made of warp threads (3) and weft threads (4), and the warp threads (3) are arranged in the belt longitudinal direction and the weft threads (4) are arranged in the belt width direction. A polyester monofilament yarn is used as the weft yarn (4).

A polyurethane elastic yarn or a polybutylene terephthalate multifilament yarn is used as the warp yarn (3). A polyester monofilament yarn is used as the weft yarn (4).

Regarding the modulus and bending rigidity of the 2-ply product, Table 1 shows a comparison between the flat belt according to the present invention and the conventional product.

How to obtain the modulus E of the belt The strain amount ε and the stress σ of the belt are measured while the belt is pulled, and the modulus E is calculated according to Hooke's law (E = σ / ε). The test conditions are as follows.

Specimen size 10 ^w × 400 (dumbbell type) Tension speed 50 ^mm / min Marking distance 200 mm Environmental conditions 20 ° C, 60% How to calculate the belt bending rigidity EI I is the moment of inertia of the belt and is calculated by the following formula. To be

The modulus E is obtained as described above, and the bending rigidity is the product of the modulus E and the moment of inertia of area. As is clear from Table 1, the modulus in the longitudinal direction and the bending rigidity of the flat belt of the present invention are the same as those of the conventional flat belt. Compared to the belt
It has decreased significantly. This is because polyurethane elastic yarn was used as the warp of the core.

Next, a running test was conducted using the flat belt of the present invention, and comparison was made with the conventional flat belt.

[Running test]

The device used for the running test is a knife edge conveyor (belt width 450 mm, machine length 2000 mm) as shown in FIG. 4, and this conveyor is generally difficult to adjust running.

In FIG. 4, (5) is a crown pulley, (6) is a knife edge plate, (7) is a drive pulley, and (8) is a tension pulley.

Two types of crown pulley (5) were used, one with a crown height of 0.8 mm (normal height) and the other with a crown height of 2.5 mm (slightly high).

Results a. In the pulley according to the present invention, the 2.5 mm crown pulley (5) was more stable in running than the 0.8 mm crown pulley (5), and the running position did not change even when the forward and reverse movements were performed.

On the other hand, the conventional flat belt traveled unstablely with both the 0.8 mm and 2.5 mm crown pulleys (5), and the belt could not travel at a predetermined position unless each pulley of the apparatus was adjusted.

b. As described in the above a, since the flat belt according to the present invention is excellent in running property, the time required for running adjustment can be shortened to about 1/4 of that in the conventional case.

c. The flatness of the flat belt according to the present invention during running was not different from that of the conventional flat belt, and vertical wrinkles did not occur at all.

Even when the polybutylene terephthalate multifilament yarn is used as the warp yarn (3) of the core body (1), the same performance (Table 1) as the polyurethane elastic yarn can be exhibited.

〔The invention's effect〕

In the present invention, the modulus in the belt longitudinal direction is made significantly smaller than the modulus in the belt width direction.

Therefore, the flat belt extends well in the longitudinal direction of the belt and is in close contact with the crown pulley, so that vertical wrinkles do not occur and the running is not unstable. By stabilizing the travel, the time required for travel adjustment can be shortened. Further, even if the crown height is increased, the belt is in close contact with the pulley, so that a larger crown effect can be obtained and the running can be further stabilized.

Further, since the absolute value of the modulus in the belt longitudinal direction becomes small, the reaction forces a ₁ and a ₁ of the tension on the left and right of the belt are reduced.
_{In the case of 2} , the influences of the respective distortion amounts are lessened, and they are balanced. As a result, the running of the belt is stable and the adjustment time can be shortened.

Due to the above effects, the flat belt according to the present invention can be used for a belt that requires a high crown height as in the case where the belt width is wide and the belt length is short. In addition, high running stability can be obtained even when several narrow belts are used in parallel. In both cases, the time required to adjust the traveling of the pulley and the like is significantly reduced.

[Brief description of drawings]

1 to 3 are drawings showing an embodiment of the present invention. FIG. 1 is a partially cutaway perspective view of a 1-ply flat belt. FIG. 2 is a partially cutaway perspective view of a flat belt of a two-ply product. FIG. 3 is an explanatory diagram showing the tension of the belt that is in close contact with the crown pulley. FIG. 4 is a schematic view showing a knife edge conveyor. FIG. 5 is a perspective view showing a belt traveling state in which traveling is unstable. FIG. 6 is a perspective view showing another mode of belt traveling in which traveling is unstable. (1) ... Core body (2) ... Synthetic resin layer (3) ... Warp yarn (4) ... Weft yarn (5) ... Crown pulley (9) ... Flat belt a ₁ , a ₂ ... Tension reaction force b ₁ , b ₂ … Component force in the pulley surface direction c ₁ , c ₂ … Component force perpendicular to the pulley surface

Claims (3)

[Claims] 1. A flat belt comprising a thermoplastic resin layer and a core, wherein the modulus in the belt longitudinal direction is 3.25 to 15% of the modulus in the belt width direction. 2. The core body comprises polyurethane warp threads as warp threads,
The flat belt according to claim 1, wherein the weft yarn is a polyester monofilament yarn. 3. The flat belt according to claim 1, wherein the core body has warp yarns made of polybutylene terephthalate multifilament yarns and weft yarns made of polyester monofilament yarns.