Process for producing an endless belt

An endless belt comprising a belt main body prepared from a liquid castable elastomeric material, a reinforcing fabric providing over the surface of the main body, and a shock absorbing layer of elastomeric material formed between the main body and the fabric. The belt is in the form of a flat belt or a belt having teeth or projections on at least one side thereof, has improved bending resistance and is operable with diminished noise. The belt is prepareed by a process comprising the steps of forming a shock absorbing layer of elastomeric material over the surface of a reinforcing fabric, fitting the fabric to one of an inner die and an outer die with the layer facing the other die, and pouring or injecting a liquid castable elastomeric material into a space between the fabric and the other die for molding.

FIELD OF THE INVENTION AND RELATED ART STATEMENT 
The present invention relates to endless belts and processes for producing 
the same. 
Endless belts for power transmission and transport include those of various 
shapes, such as flat belts, belts having projections or teeth and belts of 
special shape, which are designed for various uses. 
For example, toothed endless belts for transmission, which comprise a belt 
main body and projections or teeth formed integrally therewith, have found 
use in every field as important means for power transmission. The 
characteristics of such belts which assure synchronized transmission are 
indispensable to power transmission systems. Especially, toothed endless 
belts prepared from a liquid castable elastomeric material such as 
polyurethane are considered best suited to power transmission systems and 
transport systems which must be free of contamination with rubber 
fragments or the like, because of the material used. 
With toothed endless belts of polyurethane or the like, problems are 
encountered when the teeth of such material are merely formed integrally 
with the belt main body. When meshing with the toothed portion of a 
pulley, the belt markedly evolves heat due to the frictional resistance 
involved and has its teeth worn away, hence low durability. The belt has 
another drawback in that when driven, the meshing engagement between the 
belt teeth and the teeth of the pulley produces noises. 
Accordingly, Examined Japanese Patent Publication SHO 49-5912 proposes an 
endless belt prepared from polyurethane or like liquid castable 
elastomeric material and comprising a belt main body and teeth made 
integrally therewith and covered with a reinforcing fabric over the 
surface. The reinforcing fabric covering the toothed surface protects the 
teeth during use, giving the belt increased resistance to shearing and 
abrasion and therefore improved durability, and also produces a shock 
absorbing effect during meshing, thereby serving to mitigating heat 
generation and noises. 
However, if the reinforcing fabric is merely provided over the toothed 
surface, the belt is not fully satisfactory in respect of resistance to 
bending and reduction of noise, depending on the material and thickness of 
the fabric. The belt thus still remains to be improved. 
Conventional endless belts are molded by pouring or injecting a liquid 
castable elastomeric material into a die wherein a reinforcing fabric 
provided along the inner periphery thereof. In this process, the 
reinforcing fabric is adhered to the toothed surface with the elastomeric 
material. Nevertheless, the adhesion of the fabric to the toothed surface 
is low, such that when the belt is used for a prolonged period of time, 
the fabric is likely to separate off the toothed surface. Further when the 
surface of the reinforcing fabric is left totally uncovered, the fabric 
produces a higher shock absorbing effect to diminish heat generation and 
noises but becomes markedly damaged. 
These problems are encountered not only with toothed belts but also with 
flat belts wherein the belt main body is made of liquid castable 
elastometic material and covered with a reinforcing fabric, and further 
with various other belts. 
Further toothed endless belts are produced using inner and outer dies and a 
reinforcing fabric preshaped in conformity with the configuration of the 
desired toothed portion, by fitting the fabric to the outer periphery of 
the inner die having indentations for forming the toothed portion, and 
injecting polyurethane or the like into the space between the two dies, so 
that the fabric is adhered to the toothed surface. Accordingly, this 
process has the following problems. 
With the conventional process, the preshaped reinforcing fabric must be 
properly positioned around the indented outer periphery of the inner die. 
The procedure for winding the fabric around the die is therefore very 
cumbersome, whereas if the fabric is not properly positioned, the teeth 
obtained will not be uniform in configuration. When there is a clearance 
between the die and the fabric, voids are liable to occur, and it becomes 
difficult to prepare an endless belt free from voids. Further 
conventionally, the preshaped fabric is merely used which is not treated 
for filling the openings thereof. Accordingly, polyurethane or like 
material is likely to penetrate through the fabric to the surface side 
thereof locally, producing variations locally in the shock absorbing 
effect to be afforded by the reinforcing fabric and failing to provide a 
product of uniform quality. 
OBJECTS AND SUMMARY OF THE INVENTION 
The present invention has been accomplished to overcome the foregoing 
problems heretofore experienced. 
More specifically, a first object of the invention is to provide an endless 
belt which is operable with less bending fatigue and diminished noise and 
which has improved bending resistance, and also to provide a process for 
producing the belt easily. 
To fulfill the first object, the invention provides an endless belt 
including a belt main body prepared from a liquid castable elastomeric 
material and a reinforcing fabric provided on the surface of the main 
body, the endless belt being characterized in that a shock absorbing layer 
of elastomeric material is provided between the main body and the 
reinforcing fabric. The invention also provides a process for producing 
the endless belt comprising the step of forming a shock absorbing layer of 
elastomeric material over the surface of a reinforcing fabric, the step of 
fitting the reinforcing fabric to one of an inner die and an outer die 
with the shock absorbing layer facing the other die, and the step of 
pouring or injecting a liquid castable elastomeric material into a space 
between the reinforcing fabric and the other die for molding. 
A second object of the invention is to provide an endless belt which 
comprises a reinforcing fabric and a belt main body and wherein the fabric 
is prevented from separating from the main body and precluded from damage, 
the belt thus having high durability. The invention also provides a 
provides a process for producing the belt easily. 
To fulfill the second object, the invention provides an endless belt 
including a belt main body prepared from a liquid castable elastomeric 
material and a reinforcing fabric provided on the surface of the main 
body, the endless belt being characterized in that a thin layer is formed 
on the surface of the reinforcing fabric integrally with the belt main 
body by causing the liquid castable elastomeric material to penetrate into 
the fabric. The invention also provides a process for preparing the 
endless belt comprising the steps of fitting a reinforcing fabric to one 
of an inner die and an outer die, pouring or injecting a liquid castable 
elastomeric material into a space between the reinforcing fabric and the 
other die, and applying a pressure to the liquid castable elastomeric 
material to force the reinforcing fabric into intimate contact with said 
one die and to cause the elastomeric material to penetrate into the 
fabric. 
A third object of the invention is to provide a process for forming an 
endless belt including a belt main body having teeth or like projections 
integrally formed therewith and a reinforcing fabric provided on the 
surface of the main body along the projections, wherein the reinforcing 
fabric to be provided along the projections can be easily and properly 
fitted to an indented surface of a die for forming the projections. 
To fulfill the third object, the present invention provides a process for 
forming an endless belt comprising fitting a reinforcing fabric to one of 
an inner die and an outer die which has indentations for forming 
projections, the reinforcing fabric being stetchable and subjected to an 
opening filling treatment, fixing the opposite selvages of the fabric, 
pouring or injecting a liquid castable material into a space between the 
inner and outer dies and applying a pressure to the liquid castable 
material to cause the fabric to stretch and extend along the indented 
surface.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The present invention will be described below with reference to the 
illustrated preferred embodiments. 
EMBODIMENT 1 
FIG. 1 shows a toothed belt 1 for transmission, which comprises a belt main 
body 2 and teeth 4 formed integrally therewith on the inner side thereof 
and spaced equidistantly circumferentially of the body, with land portions 
3 interposed between the teeth 4. A reinforcing fabric 5 is provided over 
the toothed surface. With reference to FIG. 2, the belt body 2 and the 
teeth are prepared from a liquid castable elastomeric material such as 
liquid castable polyurethane. The main body 2 has embedded therein a 
tension material 6 extending helically. As seen in FIG. 2, a shock 
absorbing layer 7 made of impermeable elastomeric material such as 
thermoplastic polyurethane is formed between the toothed surface and the 
fabric 5, has a uniform thickness and extends over the entire inner 
periphery of the belt main body 2. 
FIG. 3 shows a die assembly for use in producing the toothed belt 1. FIG. 3 
shows an inner die 8 and an outer die 9 which are arranged concentrically, 
with a specified space 10 formed therebetween. The dies are separable from 
each other. An upper closure 11 and a lower closure 12 are removably 
attached to the upper and lower ends of these dies 8, 9, respectively for 
sealing off the space 10 defined by the inner and outer dies 8, 9. The 
upper closure 11 is formed with an air vent 13 in communication with the 
space 10. A closing screw 14 is removably screwed into the vent 13. A 
container 15 containing a castable elastomeric material 16 is connected to 
the outer die 9 by a duct 17. When a predetermined pressure P is applied 
to a piston 18, the elastomeric material 16 can be injected into the space 
10 between the dies 8, 9 through the duct 17. As shown in FIGS. 4 and 5, 
indentations 19 for forming the teeth 4 of the belt 1 are formed in the 
outer periphery of the inner die 8 over the entire circumference. 
For producing the toothed belt 1, a stetchable woven nylon fabric, 
polyester fabric or the like is used as the reinforcing fabric 5. A 
solution of polyurethane is applied to the fabric (in an amount of 100 to 
500 gf/m.sup.2 when dried) to close or fill the openings of the fabric, 
and the shock absorbing layer 7 of specified thickness is formed on the 
fabric 5. Next, the fabric 5 is cut to a predetermined length, and the 
length of fabric is made into an endless tubular form as by stitching by a 
sewing machine, adhesion or fusion with a heat press, or fusion by an 
ultrasonic machine, welder or high-frequency welder. The fabric 5 is then 
fitted around the inner die 8, with the shock absorbing layer 7 facing the 
outer die 9. A tension material 6 is then helically wound around the inner 
die 8 over the fabric 5. A rope of aromatic polyamide fiber is used as the 
tension material 6. After the fabric 5 and the material 6 have been 
completely provided around the inner die 8, the die 8 is inserted into the 
outer die 9 to form a combination with the specified space 10 provided 
between the two dies 8, 9. At this time, the selvages of the fabric 5 are 
folded over the upper and lower ends of the inner die 8 toward the center 
and clamped between the inner die 8 and the upper and lower closures 11, 
12 for fixing. The combination of the dies 8, 9 is heated in its entirety 
to about 110.degree. C., and pressure P (up to 2 kg f/cm.sup.2) is 
thereafter applied to the elastomeric material 16 within the container 15 
by the piston 18, filling the material 16 into the space 10 via the duct 
17. The material 16 is a mixture of polyurethane polymer and curing agent 
and has a viscosity of 2000 to 4000 cps. While filling the space 10, the 
elastomeric material 16 flows out from the vent 13, whereupon the closing 
screw 14 is screwed into the vent 13 to close the vent 13. After the space 
has been sealed off in this way, pressure molding operation at 10 to 30 kg 
f/cm.sup.2 and at 110.degree. C. for 60 minutes causes the elastomeric 
material 16 to apply the pressure to the fabric 5. The material 16 does 
not penetrate through the fabric 5 toward the inner die 8 since the fabric 
openings are closed with the shock absorbing layer 7, with the result that 
the fabric 5 is deformed in conformity with the configuration of the 
indented outer periphery of the inner die 8 by the pressure while being 
stretched to properly intimately fit to the inner die outer surface 
without leaving any clearance. The application of the pressure does not 
move or displace the fabric 5 because the selvages of the fabric 5 are 
held clamped between the inner die 8 and the upper and lower closures 11, 
12 during the operation. On curing of the material 16, the upper and lower 
closures 11, 12 are removed, the inner and outer dies 8, 9 are separated 
to release the molded product, and the product is cut in slices of 
specified width, whereby toothed belts 1 can be obtained. 
The toothed belt 1 thus produced has between the reinforcing fabric 5 and 
the teeth 4 the shock absorbing layer 7 which is softer or harder than the 
belt main body 2 and the teeth 4. While the belt is in use, therefore, the 
shock absorbing layer 7, as well as the fabric 5, produces a cushioning 
effect to mitigate noises. The presence of the shock absorbing layer 7 
also affords improved bending resistance. Even when the shock absorbing 
layer 7 is hard, the elastomeric material can be prevented from 
penetrating into the fabric 5 before curing, with the result that when the 
layer 7 is very thin, the belt exhibits a greater shock absorbing effect 
and higher bending resistance than when the layer 7 is absent. Further the 
present of the impermeable shock absorbing layer 7 permits the fabric 5, 
which is stretchable, to fit to the indented surface (19) of the inner die 
readily, properly and intimately when the pressure is applied. 
Consequently, void-free belts can be obtained easily. The shock absorbing 
layer 7 closing the openings of the fabric 5 precludes the elastomeric 
material 16 from penetrating into the fabric, eliminating the likelihood 
of local penetration of the material 16 that would lead to variations in 
the quality of the product. This facilitates the production procedure and 
assures the toothed belt 1 of high quality. 
The reinforcing fabric 5 may be one prepared by applying a polyurethane 
solution to an aforementioned fabric material, drying the fabric for 
opening closing treatment (filling treatment), forming a shock absorbing 
layer 7 over the resulting fabric and thereafter forming a tooth pattern 
in conformity with the configuration of the indentations 19 in the inner 
die 8. The fabric 5 to be prepared before use may have a wave pattern or 
the like resembling the tooth pattern. The fabric 5 thus prepared can also 
be intimately fitted to the inner die 8 by the pressure applied for 
molding since the fabric per se is stretchable. Accordingly, when to be 
provided around the inner die 8, the fabric 5 need not be completely 
fitted to the indented surface (19) of the die, hence facilitated work. 
The elastomeric material 16 may be filled into the space 10 between the 
inner and outer dies 8, 9 by injection in a vacuum or pouring at 
atmospheric pressure instead of using the piston 18. 
The molding pressure may be applied for several seconds. More specifically, 
pressure may be applied until the fabric 5 fits to the indented surface 
(19) of the inner die 8, and the space 10 may thereafter be maintained in 
a vacuum or at atmospheric pressure insofar as the reverse flow of the 
material 16 is prevented. 
Further in order to render the fabric 5 readily fittable in the 
indentations 19 of the inner die 8, the air around the tooth portion may 
be removed by application of a vacuum through the inner die 8 
simultaneously with the application of pressure. 
EMBODIMENT 2 
The shock absorbing layer 7 is prepared from a film or sheet 20 of 
polyurethane or the like, which is laminated to the surface of the 
reinforcing fabric 5 by fusion using a heat press 21 as shown in FIG. 6 
for the filling treatment of the fabric. In this case, the fabric 5 and 
the material 20 are prepared in the form of rolls 22, 23, respectively, 
from which they are paid off in the direction of arrow shown and laminated 
as superposed one over the other by the heat press 21. The material 20 is 
about 0.01 to about 1.00 mm. 
EMBODIMENT 3 
FIGS. 7 and 8 show a die assembly which comprises an inner die 8 having a 
smooth-surfaced outer periphery and an outer die 9 with indentations 24 
formed in its inner periphery. In this case, a reinforcing fabric 5 is 
fitted to the outer die inner periphery having the indentations 24, and 
the selvages of the fabric is fixed by being clamped between the outer die 
9 and upper and lower closures 11, 12. A tension material 6 is wound 
around the inner die 8. 
The product molded has teeth 4 and the fabric 5 on its outer periphery. The 
product is then cut in slices of specified width, and each cut piece 
obtained is turned inside out, whereby a toothed belt 1 is prepared like 
the one shown in FIG. 1. 
EMBODIMENT 4 
FIG. 9 shows a toothed belt 1 of the symmetric type comprising a belt main 
body 2 and teeth 4 and 25 formed symmetrically on the inner and outer 
peripheries of the body, respectively. FIG. 10 shows a toothed belt 1 of 
the asymmetric type having inner teeth 4 and outer teeth 25 which are 
displaced from the former circumferentially of the belt. These belts 1 
also have a shock absorbing layer 7 (27) between a surface covering 
reinforcing fabric 5 (26) and the teeth 4 (25) and are prepared by the 
following method. 
With reference to FIG. 11, in this case, dies 8, 9 are used which are 
formed with indentations 19, 28 for forming the teeth 4, 25 respectively. 
A reinforcing fabric 5 and tension material 6 are wound around the inner 
die 8, and like fabric 26 is fitted to the inner periphery of the outer 
die 9. The same work procedure as above thereafter follows. 
EMBODIMENT 5 
FIG. 12 shows a toothed belt 30 comprising a belt main body 2 which is 
integrally formed with teeth 4 on its inner periphery and V-shaped ridges 
29 on its outer periphery. The toothed inner surface of the belt and the 
outer belt surface having the ridges 29 are covered with reinforcing 
fabrics 5, 31, respectively, with a shock absorbing layer 7 or 32 formed 
therebetween. 
With reference to FIG. 13, the belt is prepared using an outer die 9 having 
in its inner periphery indentations 33 for forming the ridges 29, by the 
same work procedure as embodiment 4. 
EMBODIMENT 6 
FIG. 14 shows a toothed belt 1 having a protective film 34 formed over the 
entire surface of a reinforcing fabric 5, in addition to its shock 
absorbing layer 7. The protective film 34 may be made of the same material 
as the layer 7 or a different material. 
When it is intended to merely render the reinforcing fabric fittable to the 
die by filling treatment, a film 35 may be formed over the surface of the 
fabric 5 as seen in FIG. 15. In this case, however, the elastomeric 
material 16 penetrates into the fabric 5. 
EMBODIMENT 7 
FIGS. 16 to 20 show embodiments for use as flat belts 36 for transmission 
or transport. The main body 2 of the belt of FIG. 16 has no tension 
material 6 therein. The reinforcing fabric 5 used is a woven polyester 
fabric which is less stretchable and is formed with a shock absorbing 
layer 7. 
The belt of FIG. 17 has the same construction as the flat belt 36 of FIG. 
16 except that the belt main body 2 has a tension material 6 embedded 
therein. 
FIG. 18 shows a flat belt 36 wherein the belt main body 2 is provided with 
reinforcing fabrics 5, 37 on its inner and outer surfaces, respectively. A 
shock absorbing layer 7 (38) is interposed between the main body 2 and the 
fabric 5 (37). 
The belt main body 2 of FIG. 19 is provided with reinforcing fabrics 5, 37 
over the inner and outer surfaces thereof, respectively, with a shock 
absorbing layer 7 (38) interposed between the main body 2 and the fabric 5 
(37). The belt body 2 has incorporated therein a tension material 6 
positioned close to the layer 7. 
FIG. 20 shows a belt wherein the main body 2 includes a tension material 6 
close to its inner periphery and has a shock absorbing layer 7 and a 
reinforcing fabric over the outer periphery. 
These flat belts 36 can be prepared in the same manner as the foregoing 
embodiments. 
In the case of the flat belts 36, an endless hollow weave is usable for the 
reinforcing fabrics 5, 37. 
EMBODIMENT 8 
FIG. 21 shows a flat belt 36 wherein the belt main body 2 has a tension 
material 6 embedded therein approximately at the midportion its thickness. 
To prepare this belt, a reinforcing fabric 5 formed with a shock absorbing 
layer 7 is fitted around an inner die 8, an elastomeric material 16 is 
filled into a space between the fabric and an outer die 9a to form an 
inner peripheral portion 2a of the belt body 2 first as seen in FIG. 22. 
The outer die 9a is then removed, a tension material 6 is wound around the 
portion 2a as formed around the die 8, the resulting assembly is placed 
into another outer die 9b, and elastomeric material 16 is filled into the 
space 10 formed to mold an outer peripheral portion 2b integrally with the 
portion 2a as seen in FIG. 23. In this way, the tension material 6 can be 
embedded in the belt body 2 at the desired position with respect to the 
direction of its thickness. 
EMBODIMENT 9 
FIG. 24 shows a toothed belt 40 comprising a belt main body 2 and teeth 4 
which are made of an elastomeric material 16, and a thin layer 39 formed 
over the entire surface of a reinforcing fabric 5 by the penetration of 
the material 16. The teeth 4 are formed integrally with the belt body 2 
from the elastomeric material 16. As seen in FIG. 25, the fabric 5 is held 
adhered with the elastomeric material 16 forming the teeth 4 by the 
penetration and curing of the material, and the layer 39 is uniformly 
formed over the entire surface of the fabric 5 integrally with the teeth 4 
by the penetration of the material 16. The elastomeric material 16 has 
fully penetrated into the mesh portions formed by the warps 41 and wefts 
42 of the fabric 5 and also into the yarns 41, 42 between their fibers. 
The belt 40 shown in FIG. 24 is produced by the following process. A woven 
nylon, polyester or like reinforcing fabric 5 is coated with the same 
material as the liquid castable elastomeric material 16, for example, with 
a solution of polyurethane, in an amount of about 10 to about 30 g 
f/m.sup.2 when dried, i.e., in such an amount as to enable the fabric to 
retain the tooth pattern to be formed without filling up the openings 
thereof. Next, the reinforcing fabric 5 is press-formed to form a tooth 
pattern using a heat press 45 having a pair of upper and lower dies 43, 44 
as seen in FIG. 26, and is thereafter cut to a predetermined size. The cut 
piece is made into an endless tube by stitching with a sewing machine or 
adhesion or fusion with a heat press. With reference to FIGS. 27 and 28, 
the endless fabric 5 is fitted around the inner die 8 of the die assembly 
in conformity with the configuration of indentations 19, and a tension 
material 5 is helically wound around the inner die 8 over the fabric 5. 
The inner die 8 having the fabric 5 and tension material 6 completely 
fitted thereto is then inserted into the outer die 9, with a specified 
space 10 formed therebetween. At this time, the selvages of the fabric 5 
are folded over the upper and lower ends of the inner die 8 toward its 
center and clamped between the die 8 and upper and lower closures 11, 12 
for fixing. The combination of the dies 8, 9 is heated in its entirety to 
about 110.degree. C., and pressure P (up to 2 kg f/cm.sup.2) is thereafter 
applied to the elastomeric material 16 within the container 15 by the 
piston 18, filling the material 16 into the space 10 via the duct 17. The 
material 16 is a mixture of polyurethane polymer and curing agent and has 
a viscosity of 200 to 4000 cps. While filling the space 10, the 
elastomeric material 16 flows out from the vent 13, whereupon the closing 
screw 14 is screwed into the vent 13 to close the vent 13. A pressure of 
10 to 30 kg f/cm.sup.2 is applied to the material at 110.degree. C. for 60 
minutes for molding. During the pressure molding operation, the 
reinforcing fabric 5 preshaped to have a tooth pattern is pressed against 
the inner die 8 by the elastomeric material 16, intimately fitting to the 
die without any clearance along the indented surface. At the same time, 
the elastomeric material 16 penetrates into the mesh openings of the 
fabric to form a thin layer 39 of the material 16 over the entire toothed 
surface integrally therewith as seen in FIG. 25. After the material 16 has 
been cured, the upper and lower closures 11, 12 are removed, and the inner 
and outer dies 8, 9 are separated to release the molded product. The 
product is then cut into slices of predetermined width, whereby belts 40 
can be obtained. 
With the belt 40 thus produced, the elastomeric material 16 has penetrated 
through the reinforcing fabric 5 to the surface side thereof, adhering the 
fabric 5 to the teeth 4 very effectively, rendering the belt usable for a 
prolonged period of time without permitting the separation of the fabric 
5. The thin layer 39 of elastomeric material 16 covering the surface of 
the fabric 5 serves to protect the fabric 5, making the fabric less prone 
to damage. Since the thin layer 39 can be formed simultaneously with the 
belt body during the application of pressure after the pouring or 
injection of the material 16, the belt 40 can be produced easily. The 
reinforcing fabric 5 is brought into intimate contact with the outer 
periphery of the inner die 8 during the application of pressure. This 
results in the advantage of precluding formation of air bubbles in the 
interior die space, rendering the resulting belt free from voids. 
While the fabric 5 is treated to have a complete tooth pattern, a wavy 
pattern or the like resembling the tooth pattern may be given to the 
fabric. 
EMBODIMENT 10 
The polyurethane solution is applied to the reinforcing fabric 5 in an 
increased amount of 30 to 100 g f/m.sup.2 when dried, and a lower pressure 
(2 kg f/cm.sup.2) is applied to the elastomeric material 16 injected or 
poured in and confined in the closed space. The material 16 is maintained 
at this pressure for 5 to 15 minutes until the viscosity of the material 
16 increases to 10.sup.4 to 10.sup.10 cps and thereafter subjected to a 
pressure of 10 to 30 kg f/cm.sup.2 at 110.degree. C. for 45 to 55 minutes 
for molding. 
This method slightly diminishes the penetration of the elastomeric material 
16 into the reinforcing fabric 5, producing a thin layer 39 on the surface 
of the fabric 5 locally. However, this embodiment is equivalent or nearly 
equivalent to embodiment 9 with respect to the adhesion of the fabric 5, 
etc. 
EMBODIMENT 11 
FIGS. 29 and 30 show a die assembly which comprises an inner die 8 having a 
smooth-surfaced outer periphery and an outer die 9 formed with 
indentations 24 in its inner peripheral surface. With this assembly, the 
reinforcing fabric 5 is fitted to the indented inner surface of the outer 
die 9, and the selvages of the fabric are clamped between the upper and 
lower ends of the outer die 9 and upper and lower closures 11, 12, 
respectively. On the other hand, the tension material 6 is wound around 
the inner die 8. 
The molded product obtained has teeth 4 and fabric 5 on the outer 
periphery. The product is then cut in slices of specified width, and each 
cut piece is turned inside out. Thus, belts having the same construction 
as the belt 40 shown in FIG. 24 are produced. 
EMBODIMENT 12 
FIG. 31 shows a toothed belt 40 of the symmetric type comprising a belt 
main body 2 and teeth 4, 25 formed symmetrically on the inner and outer 
peripheries of the belt body, respectively. FIG. 32 shows a toothed belt 
40 of the asymmetric type having inner teeth 4 and outer teeth 25 which 
are displaced from the former circumferentially of the belt. These belts 
40 also have a reinforcing fabric 5 (26) covering each toothed surface and 
a thin layer 39 (46) over the surface of the fabric 5 (26). These belts 
are prepared by the following process. 
FIG. 33 shows the inner and outer dies 8, 9 to be used in this case and 
provided with indentations 19, 28 for forming the teeth 4, 25, 
respectively. A reinforcing fabric 5 and tension material 6 are wound 
around the inner die 8, and like fabric 26 is fitted to the inner 
periphery of the outer die 9. The same work procedure as already stated 
thereafter follows. 
EMBODIMENT 13 
FIG. 34 shows a toothed belt 47 comprising a belt main body 2 which is 
integrally formed with teeth 4 on its inner periphery and V-shaped ridges 
29 on its outer periphery. The toothed inner surface of the belt and the 
outer belt surface having the ridges 29 are covered with reinforcing 
fabrics 5, 31, respectively, which are formed with a thin layer 5 or 48 
over the surface of the fabric. 
With reference to FIG. 35, the belt is prepared using an outer die 9 having 
in its outer periphery indentations 33 for forming the ridges 29, by the 
same work procedure as embodiment 12. 
EMBODIMENT 14 
The endless belt having a thin layer 39 on the surface of the reinforcing 
fabric 5 can be in the form of a flat belt, V belt or the like. For 
example, the belts shown in FIGS. 16 to 20 can be so constructed when not 
having the shock absorbing layers 7, 38. Further as shown in FIGS. 36 to 
38, the thin layer may be present in combination with the shock absorbing 
layer. More specifically stated, FIG. 36 shows a belt wherein a thin layer 
39 is formed over the surface of a reinforcing fabric 5 along the inner 
periphery of the belt main body 2, and a shock absorbing layer 38 is 
interposed between the belt body 2 and a reinforcing fabric 37 along the 
inner periphery of the body 2. 
FIG. 37 shows a belt which is in reverse inside-outside relation to the 
flat belt of FIG. 36. The belt main body 2 has a tension material 6 
incorporated therein. 
FIG. 38 shows a belt having the same construction as the flat belt of FIG. 
36 except that the belt main body 2 has a tension material 6 incorporated 
therein. 
With the flat belts shown in FIGS. 36 to 38, one of the fabrics 5, 37, i.e. 
the fabric 37, is exposed, while the other fabric 5 is covered with the 
thin layer 39. Accordingly, the belt inner and outer surfaces differ in 
coefficient of friction, rendering the belt very convenient to use for 
transport and other applications. 
While various embodiments of the invention have been described above, 
useful materials for the belts of the invention are as follows. 
Examples of useful reinforcing fabrics are woven fabrics cut bias, woven 
fabrics formed by highly stretchable yarns, nonwoven fabrics, etc. 
Examples of useful woven fabrics are in the form of plain weave, twill 
weave, satin weave and the like prepared from yarns of elastic fibers, 
rubber yarns and crimped yarns. 
For the filling treatment, a suitable method is used in view of the bending 
resistance of the reinforcing fabric and reduced likelihood of producing 
noises. Useful materials for the treatment are polyurethane solutions, and 
polyurethane or like films or sheets which may be finely porous. While the 
same material as the elastomeric material 16 is useful, other materials 
which can be adhered are usable. 
Examples of liquid castable elastomeric materials 16 are polyurethane 
polymer and like thermosetting liquid resins, liquid rubbers, plastisols, 
molten thermoplastic resins, etc. The hardness of the liquid castable 
elastomeric material as cured in the form of a product is suitably 70 to 
100 degrees in JIS A hardness. The hardness may be in the range of 
durometer A20 to durometer D80. 
Examples of useful tension materials 6 are ropes of synthetic fibers, such 
as aromatic polyamide, nylon, polyester and like fibers, steel wires, etc. 
The endless belts of the invention are not limited to the foregoing 
embodiments in construction and configuration but can be various insofar 
as the belt main body 2 has a reinforcing fabric. For example, the 
invention can be embodied as endless belts for transport, such as those 
shown in FIGS. 39 and 40, in which the belt main body 2 has a multiplicity 
of widthwise projections 49 formed on its outer periphery and arranged at 
a specified spacing along the periphery, so as to transport articles in 
engagement with the projections 49. FIG. 41 shows another example, wherein 
sawtooth projections 50 are provided on the outer periphery of the belt 
main body 2. 
When the reinforcing fabric is provided as exposed, the surface of the 
fabric can be covered with a layer of silicone, fluorocarbon resin or like 
synthetic resin or elastomer. The coefficient of friction of the fabric 
surface can then be varied as desired, rendering the belt applicable to 
wider use.