GREEN COVER V-BELTS AND A METHOD OF MAKING THEM

FIELD OF THE INVENTION

This invention relates in general to power transmission drive belts, and in particular to a wrapped V-belt having a green dyed outer fabric and chloroprene rubber frictioned inner fabric which are wrapped on the V-belt body. It has a high tenacity tensile member which acts as a tension support layer. The invention also relates to the method for making the Green Cover wrapped V-belt.

BACKGROUND AND PRIOR ART

A V-belt cross section has a wedge shape and this external profile engages on a corresponding V-grooved pulley. One common form of V-belt is a fabric covered V-belt in which the body of the belt is composed of an elastomeric material and reinforcing cords, which is then wrapped with a fabric. Such a V-belt with polyester cord construction having elongation around 0.8%. Due to belt elongation, there is a drop in tension which causes excess heat build-up and results in base rubber hardening and cracking. This requires frequent maintenance. .Also high coefficient of friction on the outer surface due to elastomeric material on both sides of the fabric, reduces the belt life.

Hence there is a need for a V-belt which will not elongate during service and has a reduced coefficient of friction, long service life, maintenance free and compact drive.

The present invention meets the above mentioned need and other associated needs.

OBJECTS OF THE INVENTION

The primary object of the invention is to provide a V-belt which will not elongate during service and has reduced coefficient of friction, low heat generation and increased service life.

A further object of the invention is to provide a V-belt with 40% higher power transmission capacity with the same tension of conventional belt.

Yet another object of the invention is to provide a V-belt which has improved wear characteristics in operation and needs minimum maintenance, as the tension is stable throughout its service life.

How the foregoing objects are achieved will be clear from the following description. In this context it is clarified that the description provided is non-limiting and is only by way of explanation.

SUMMARY OF THE INVENTION

Accordingly, the present invention provides a Green Cover V-belt comprising of a basal body portion, a topping section and a load carrying section. The latter is made from a continuously wound high tenacity load carrying cords being enveloped within a first or inner fabric layer. This layer is covered by a second green dyed fabric outer layer that is impregnated with an elastomeric material only on its inner side.

Preferably, the body portion and topping section are made primarily of polychloroprene rubber compound.

More preferably, the load carrying cords are high tenacity aramid cable cords which will not elongate during service and are embedded in a cord adhesive layer to ensure strong bonding between the cords and the polymeric material of the body portion.

Even more preferably, the first or inner fabric layer, is a polychloroprene rubber impregnated polycotton fabric which engages with the body portion.

Most preferably, the second or outer fabric layer comprises of green dyed cotton fabric impregnated with polychloroprene rubber compound only on its inner side and the other side, which forms the outermost surface of the belt has a comparatively less coefficient of friction.

The present invention also provides a method for manufacturing the Green Cover V-belt as described hereinbefore. The method at the outset comprises forming the base and topping layer of the said belt with polychloroprene rubber compound. Then the tension support layer is interposed between the base layer and the topping Layer. Thereafter, the first or inner fabric layer is enveloped around the body portion. Then the method involves wrapping an outer green dyed fabric cover impregnated with a polychloroprene compound on only its inner side, followed by vulcanising the belt formed.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The nature and scope of the present invention will be better understood from the accompanying drawings, which are by way of illustration of a preferred embodiment and not by way of any sort of limitation. In the accompanying drawings:-

Figure 1 is a cross sectional view of the belt according to the present invention.

Figure 2 shows stretch % of conventional V-belts vs Green Cover V-belts.

Figure 3 shows the power rating comparison graph wherein power rating of a conventional V-belt has been compared with that of a Green Cover V-belt according to this invention.

Figure 4 shows the test life comparison of conventional V-belts and Green Cover V-belts.

Figure 5 is a detailed process flow diagram showing various steps involved in manufacturing the belt from rubber compound to the finished product.

Figures 6 show the performace characteristics like slip and belt temperature difference of conventional V-belts vs Green Cover V-belts.

DETAILED DESCRIPTION OF THE INVENTION

Having described the main features of the invention above, a more detailed and non-limiting description of a preferred embodiment will be given in the following paragraphs with reference to the accompanying drawings.

In all the figures, like reference numerals represent like features. Further, the shape and size of the product shown are by way of example only and it is within the scope of the present invention to change the shape and size, without departing from the basic principle of the invention.

As stated previously, V-belts of the prior art have low service life due to formation of cracks caused by stress and excess heat developed in the belt. Hence belt elongation during service and coefficient of friction need to be reduced to address this issue.

In order to reduce the problem of high heat generation and high coefficient of friction, aramid cord is used and the outer fabric of the V-belt is frictioned with polychloroprene compound on one side only, which is the inner side, so that comparatively lesser coefficient of friction can be achieved in Green Cover wrapped V-belts.

The belts manufactured by the method according to the invention have low stretch characteristics and have better performance and durability.

Referring to figure 1, the belt (A) according to this invention comprises of a base body (6) made primarily of polychloroprene rubber. It has a load carrying section made from a continuously wound high tenacity load carrying aramid cable cord (4). The topping section (3) and the base compression section (6) are made of polychloroprene topping and base rubber having hardness ranging 75-85°Shore A for enhanced performance. All belt compounds have been developed to provide longer life and superior resistance to weather and oily environments.

The load carrying cords (4) are high tenacity aramid cable cords which will not elongate during service and are embedded in a cord adhesive layer (5) to ensure strong bonding between said cords and the polymeric material of the base body (6).

The belt body is enveloped with a first or inner fabric layer (2), which is wrapped around the body portion (6). It is a polychloroprene rubber impregnated polycotton fabric (2) within a distributed weight range of about 520- 550 GSM, to provide it with sufficient tackiness so that it adheres properly to the remainder of the belt material, during wrapping and becomes integrated during vulcanisation. This fabric should be cut and laid on the bias, so that its threads are at an angle of 45° to the longitudinal axis of the belt. This is done so that the greatest flexibility can be achieved in the final product.

According to the present invention, the second layer of fabric (1) comprises of a green dyed cotton fabric which is impregnated with polychloroprene rubber compound on only one side, that being its inner side. This fabric is then bias cut about 40° to 50°in a conventional manner and then used to wrap around and thereby cover the V-belt (A) as shown in figure 1. The other layer of the second layer of fabric (1) is thus its non-impregnated side. It forms the outer periphery of the belt body and provides comparatively less coefficient of friction than that of the conventional V-belt.

Figure 2 reveals that the belt stretch in percentage of V-belts according to the present invention is comparatively low as compared to conventional V-belts. This corroborates the fact that the tension remains almost stable through out the life span of the V-belts.

Figure 3 reveals that the green cover V-belt according to the present invention transmits around 40% higher power than the conventional V-belt with the same tension. This has been achieved by the high tenacity aramid cable cord which has extremely low stretch property.

Figure 4 clearly reveals that the average test life of V-belts according to the present invention is susbtantially high as compared to conventional V-belts.

Figure 5 is the detailed process flow diagram showing various steps involved in manufacturing the belt. The process of making Green Cover V-belt according to the present invention, starts with the rubber compound mixing.Rubber.carbon black and other rubber chemicals are weighed and mixed in a intermix.The rubber compound is then warmed on a open mill and fed into a profile calendering machine to form V shape base profile and topping layer is formed as a sheet in a topping calendering machine. Rubber compound sheets are then soaked in a solvent and blended to form a compound solution for the dipping of aramid cords.Simultaneously, poly cotton inner fabric and outer green dyed cotton fabric is frictioned with the polychloroprene rubber compound.This frictioned fabric is then bias cut at about 45°in a conventional manner and then slitted as a roll to wrap around the V-belt body.

Once all the above process is completed, next process is the profile building process where the high tenacity aramid cable cord with compound solution has been perfectly wound with required tension, between the base layer and topping layer. This sleeve is then cut as a single belt using roller cutter and then the slitted inner and outer fabric is flipped over the belt body. This uncured belt is then vulcanised to form a V-belt according to the present invention.

The essential manufacturing steps are as follows:

a) Forming the base (6) and topping layer (3) of the said belt with polychloroprene rubber compound.

b) Interposing the tension support layer between the base layer (6) and the topping Layer (3);

c) Enveloping the first or inner fabric layer (2) around said body portion (6).

d) Wrapping an outer green dyed fabric cover (1) impregnated with a
polychloroprene compound on only its inner side.

e) Vulcanising the belt formed in steps a) to d) to make the final Green Cover V-belt.

High tenacity aramid cable cords (4) are used as a tensile reinforcement in the Green Cover V-belt (A). These cords have greater tensile strength and excellent fatigue resistant characteristics, which can minimize the deterioration of physical properties of the belt caused by high temperature over a long period of time. These cords are embedded in a cord adhesive layer (5) which ensures strong bonding between cord and the polymeric material. They also hold the longitudinal cords in their proper transverse alignment for uniform distribution of stress and to prevent the separation of the polychloroprene top layer (3).

The V-belt (A) according to the invention reduces elongation and heat build-up between the belt and the pulley under shock load. It has an abrasion resistant double-layer fabric cover. It has an oil and heat resistant chloroprene compound body rated for 85°C, which enhance belt performance in extreme operating conditions.

Figure 6 is a graphical representation of slip in percentage and belt temperature. It is evident from this figure that belt slip is substantially less in V-belts according to the present invention. It also reveals that the V-belts according to the present invention has a body which is rated for 85°C. This is achieved by the presence of oil and heat resistant polychloroprene rubber compound.

From the description hereinbefore and also from the appended claims, it would be clear to persons skilled in the art that the Green Cover V-belt according to the present invention, offers the following non-limiting advantages:.

a) It has a long service life, will not elongate during service, comparatively less coefficient of friction and resulting in low heat generation.

b) It has a power rating of about 40% more compared to standard construction V-belts.

c) It provides high resistance to shock loads.

d) It requires minimum maintenance as the tension remains almost stable throughout its service life.

e) It has an oil and heat resistant polychloroprene rubber compound, rated for around 85nC which enhance belt performance in extreme conditions.

f) It has minimal need for re-tensioning because of aramid tensile cords.

The present invention has been described with reference to some drawings and a preferred embodiment purely for the sake of understanding and not by way of any limitation and the present invention includes all legitimate developments within the scope of what has been described herein before and claimed in the appended claims.

We claim

1. A Green Cover V-belt (A) comprising of a basal body portion (6), a topping section (3) and a load carrying section made from a continuously wound high tenacity load carrying cords (4) being enveloped within a first or inner fabric layer (2) which layer is covered by a second green dyed fabric outer layer (1) that is impregnated with an elastomeric material only on its inner side.

2. The Green Cover V-belt as claimed in claim 1, wherein said body portion (6) and topping section (3) are made primarily of polychloroprene rubber compound.

3. The Green Cover V-belt as claimed in claims 1 and 2, wherein said load carrying cords (4) are high tenacity aramid cable cords which will not elongate during service and are embedded in a cord adhesive layer (5), to ensure strong bonding between said cords and the polymeric material of body portion (6).

4. The Green Cover V-belt as claimed in claims 1 and 2, wherein said first or inner fabric layer (2), is a polychloroprene rubber impregnated polycotton fabric which engages with the body portion (6).

5. The Green Cover V-belt as claimed in claims 1 and 2, wherein said second or outer fabric layer (1) comprises of green dyed cotton fabric impregnated with polychloroprene rubber compound only on its inner side and the other side, which forms the outermost surface of said belt (A) has a comparatively less coefficient of friction.

6. A method for manufacturing the Green Cover V-belt as claimed in claims 1 to 5 comprises the steps of:

a) Forming the base (6) and topping layer (3) of the said belt with polychloroprene rubber compound.

b) Interposing the tension support layer between the base layer (6) and the topping
Layer (3);

c) Enveloping the first or inner fabric layer (2) around said body portion (6).

d) Wrapping an outer green dyed fabric cover (1) impregnated with apolychloroprene compound on only its innerside.

e) Vulcanising the belt formed in steps a) to d) to make the final Green Cover V-belt.