JPH0874936A - V-ribbed belt and its manufacture - Google Patents

Abstract

PURPOSE: To reduce a cutting loss during V-rib cutting in a bottom rubber part so as to reduce costs. CONSTITUTION: Each of V-ribs 3,... in a V-ribbed belt is made of short fiber mixed rubber and is formed by grinding a rib surface in a V-rib part, which is preformed by extrusion molding into a shape complying with the V-rib and having a slightly larger dimension than the V-rib. In each of the ribs 3,..., short fibers 3... are arranged three-dimensionally in the belt longitudinal direction, in the belt width direction, and in the belt vertical direction, and its mixing rate in the belt width direction is set to 30% or more.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a V-ribbed belt in which a plurality of V-ribs extending in the belt longitudinal direction are formed on a belt base belt and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, as a power transmission belt, a V-ribbed belt is known in which a plurality of V-ribs extending in the belt longitudinal direction are formed on a belt base belt. The manufacture of such a V-ribbed belt is generally performed as follows (see FIG. 17).

A rubber containing short fibers is kneaded by a kneader a.

The kneaded rubber b is rolled by a calendar c and taken as a rubber sheet d by a conveyor e. At this time, the thickness of the rubber sheet d is about 0.6 to 1.0 mm, and the short fibers are oriented in the longitudinal direction.

A rubber sheet d having a predetermined thickness is obtained by stacking the rubber sheet d in a thickness required for molding.

The rubber sheet is cut in a direction perpendicular to the longitudinal direction to form rubber pieces f, ... And then the rubber pieces f ,. As a result, the short fibers are oriented in the width direction.

A belt material other than a rubber sheet is assembled in a molding die h, and the rubber sheet g obtained in the above is attached to the molding die h, which is cut to a required length and the ends are butt-joined.

A vulcanization can is loaded and vulcanized and molded.

The vulcanized molded product m is removed from the molding die h.

The bottom rubber portion m1 is ground to cut out a V-rib shape. The grinding dust generated at this time is discarded.

V is cut according to the number of ribs required and V
Get a ribbed belt.

[0012]

However, according to the method described above, it is necessary to grind the bottom rubber portion in order to form the V-rib shape, and the grinding loss of the bottom rubber portion due to the grinding increases ( In reality, the cost is about 30% of the bottom rubber portion).

Further, as described in, for example, JP-A-1-303338, there is also known a method of forming a V-rib by extruding a flat rubber plate, vulcanizing it and then grinding it. .

However, such a V-ribbed belt is
In terms of grinding loss, there is not much difference from the method using the calendar described above, and the base rubber tends to shrink in the orientation direction of the short fibers after grinding. Here, the tendency of contraction in the orientation direction of the short fibers is that the rubber tends to contract after vulcanization, which is suppressed by the short fibers, but when the V-ribs are ground by grinding, the short fibers are It is considered that the short fibers lose the function of suppressing shrinkage because they are cut.

The present invention provides a V-ribbed belt and a method for manufacturing the V-ribbed belt, in which the grinding loss in the bottom rubber portion is reduced to reduce the cost.

[0016]

The invention according to claims 1 and 2 relates to a V-ribbed belt, and claims 3 to
The invention according to claim 6 relates to a method for manufacturing the V-ribbed belt.

The invention according to claims 1 and 2 is premised on a V-ribbed belt in which a plurality of V-ribs extending in the belt longitudinal direction are formed on the belt base belt.

According to the first aspect of the present invention, the V-rib is made of a rubber blended with short fibers and corresponds to the V-rib, and the rib surface of the V-rib portion preliminarily formed by extrusion molding into a shape slightly larger than the V-rib. Is formed by grinding. In the invention according to claim 2, in the V rib, the short fibers are oriented in the belt longitudinal direction, the belt width direction, and the belt vertical direction, and the orientation ratio in the belt width direction is 30% or more.

The inventions according to claims 3 to 6 are premised on a method for manufacturing a V-ribbed belt in which a plurality of V-ribs extending in the belt longitudinal direction are formed on a belt base using a rubber compounding short fibers. To do.

According to a third aspect of the present invention, there is provided an extruder including an expansion die having a V-rib portion forming groove at an outlet portion thereof.
A first extruded cylindrical rib rubber tube having short ribs oriented in the circumferential direction and corresponding to the V ribs and having a V rib portion preformed in a shape slightly larger than the V ribs on an outer peripheral portion or an inner peripheral portion. And a second step of molding a V-ribbed belt molded body into a vulcanization mold using the cylindrical rib rubber tube, and then vulcanizing the V-ribbed belt molded body after the vulcanization. A third step of grinding the surface to form V-ribs.

In the invention according to claim 4, in the second step, a cylindrical rib rubber tube is cut along the tube axial direction to form a rib rubber sheet, and the rib rubber sheet is used to form a V-ribbed belt for a vulcanization mold. A molded body is molded.

In the invention according to claim 5, in the second step, prior to forming the V-ribbed belt molded body, a cover sheet having a convex portion having a shape corresponding to the groove portion between the V-rib portions formed on the rib rubber sheet. The rib rubber sheet is wound with the convex portion of the cover sheet fitted in the groove portion between the V rib portions.

In the second aspect of the invention, in the second step, the rubber-shaped sheet is wound around the ribbed rubber sheet so that the rib portion is engaged with the groove portion between the convex portions of the rubber-shaped sheet. The groove portion between the convex portions of the rubber type sheet has the same pitch as the V rib of the V-ribbed belt and has a smaller volume than the V rib.

[0024]

According to the first aspect of the present invention, by grinding the side surface of the V rib portion preliminarily formed by extrusion into a shape corresponding to the V rib and slightly larger than the V rib,
Ribs are formed and grinding loss is reduced.

According to the second aspect of the invention, the short fibers are oriented in the V-ribs in the belt width direction with an orientation rate of 30% or more, and desired lateral pressure resistance can be obtained.

According to the third aspect of the present invention, in the first step, the short fibers are oriented in the circumferential direction by the extruder equipped with the expansion die having the V-rib portion forming groove at the outlet portion, and the short fibers are formed on the V-rib. A cylindrical rib rubber tube having a corresponding V rib portion preliminarily formed in a shape slightly larger than the V rib on the outer peripheral portion or the inner peripheral portion is extruded, and in the second step, the cylindrical rib rubber tube is used. A V-ribbed belt molded body is molded on a vulcanizing mold and vulcanized. Then, in a third step, the rib surface of the V-rib portion of the vulcanized V-ribbed belt molded body is ground to form V-ribs. It

According to the invention of claim 4, in the second step, the cylindrical rib rubber tube extruded through the outlet portion of the expansion die is cut along the tube axial direction, and the short fibers are oriented in the lateral direction. A flat rib rubber sheet having a flat plate shape is used, and a V-ribbed belt molded body is molded on a vulcanization mold by using this.

According to the fifth aspect of the present invention, in the second step, the rib rubber sheet cut out is fitted with the convex portion of the cover sheet in the groove portion between the V rib portions prior to forming the V ribbed belt molded body. Then, it is wound up together with the cover sheet.

According to the invention of claim 6, in the second step, the V of the rib rubber sheet molded on the vulcanizing mold is
The rubber sheet is formed so that the groove portion between the convex portions engages with the rib portion at the same pitch as the V rib of the V-ribbed belt and has a smaller volume than the V rib. Provided and vulcanized.

[0030]

Embodiments of the present invention will now be described in detail with reference to the drawings.

In FIG. 1 showing a schematic structure of a V-ribbed belt, 1 is a V generally used as a power transmission belt.
The ribbed belt has a plurality of V ribs 3, ... Formed in the belt longitudinal direction with respect to the belt base belt 2. The V ribs 3 are made of short fiber compounded rubber in which short fibers are oriented in the belt width direction, and are extruded into a shape corresponding to the V ribs 3, ... And slightly larger than the V ribs 3 ,. It is formed by grinding the rib surface (rib side surface and rib bottom surface) of the V rib portion preformed by molding.

In each of the V-ribs 3, short fibers 3b, ... Are three-dimensionally oriented in the rubber 3a in the belt longitudinal direction, the belt width direction, and the belt vertical direction. The orientation rate is 30% or more.

In FIG. 1, 4 is an upper canvas layer, 5 is a core cord layer, and a core cord 5b is spirally embedded in the adhesive rubber 5a.

Next, a method for manufacturing the V-ribbed belt 1 will be described with reference to FIG.

<First Step> First, V-rib forming grooves 12c having an outer die 12a and an inner die 12b are regularly formed in the inner die 12b in the circumferential direction at the outlet of the extruder 11. The expansion die 12 (see FIGS. 3 and 4) is attached, and the short fiber is circumferentially oriented by the expansion die 12 by the extruder 11 to correspond to the V ribs 3, ... A cylindrical rib rubber tube 13 having a V rib portion 13a, which is preformed into a shape slightly larger than 3, is extruded (see FIG. 5).

By the way, in order to orient the short fibers in the circumferential direction by the expansion die 12, the central diameter R1 at the center of the rubber passage 12d of the inlet portion P1 of the expansion die 12 and the rubber of the outlet portion P2 of the expansion die 12 are used. It is necessary that the ratio of the central diameter R2 at the center of the flow channel 12d is 6.5 or more. That is,
The following formula needs to hold.

[0037]

[Equation 1] Then, the short fiber compounded rubber extruded by the extruder 11 is expanded by the expansion die 12 which is obtained when the relation of the above formula is established.
Due to the expanding action of, the short fibers are oriented in the circumferential direction.

By the way, the rubber flow path 12d of the expansion die 12
The V rib portion forming groove 12c for forming (preforming) the V rib is formed at the outlet portion P2 of the V rib portion forming groove 12c. The V rib portion forming groove 12c is simply formed at the outlet portion P2 of the rubber flow passage 12d of the expansion die 12. In addition, not only the orientation of the short fibers to be oriented in the circumferential direction is disturbed in the cylindrical rib rubber tube extruded from the expansion die 12, but also the following problems occur.

(I) The V-rib molding groove 12c serves as resistance during extrusion molding, hinders the orientation of the short fibers in the circumferential direction, and hinders the expanding action.

(Ii) Since the V-rib portion molding groove 12c becomes a resistance during extrusion and lowers the productivity, it is necessary to increase the extrusion pressure in order to prevent this. Unreasonable force acts on 11 and the expansion die 12.

(Iii) The expansion die 12 having the V-rib molding groove 12c is difficult to manufacture, expensive, and also difficult to manage.

Therefore, in order to eliminate such a problem,
Considering the shape of the V-rib of the bottom rubber part of the V-ribbed belt, the length of the V-rib molding groove in the rubber flow direction, and the appearance and changes (die swell and fiber orientation) of the cylindrical rib rubber tube extruded by the expansion die. The expansion die was manufactured as follows.

(A) The groove pitch in the circumferential direction of the V-rib portion forming groove 12c is set so as to match the V-rib pitch of the finished V-ribbed belt 1 or be slightly smaller. Here, the case where the V-rib pitch is slightly smaller than the V-rib pitch is also included. In such a case, the V-rib pitch of the finished V-ribbed belt 1 is made to pass once by passing through a roll having a groove pitch matching the V-rib pitch of the finished product. This is because they can be matched, and if this is done, a certain degree of V-rib pitch variation can be tolerated.

(B) The forming groove angle of the V-rib portion forming groove 12c is set to be larger than the rib angle of the completed V-ribbed belt 1. This is to reduce the mold flow during vulcanization so that the orientation of the short fibers is not disturbed.

(C) The V-ribbed belt is thicker than the design dimension of the vulcanization mold. This is because the cross section of the extruded rib rubber tube tends to shrink and become smaller.

(D) The orientation of the short fibers in the extruded cylindrical rib rubber tube is disturbed by providing the V-rib portion forming groove 12c in the expansion die 12, but the orientation of the V-rib portion forming groove 12c is disturbed. By shortening the length in the rubber flow path direction and lowering the height, it is possible to make the turbulence extremely small.

An example of the dimensions of the V-ribbed belt and the expansion die used to form the V-ribbed belt will be specifically shown. 6 and 7, L1 = 3.50 mm, L
2 = 2.20 mm, L3 = 1.75 mm, rib angle θ1 = 5
0 °, L11 = 3.56 mm, L12 = 2.52 mm, L13 =
2.28mm, L14 = 3.36mm, L15 = 1.49mm, L
16 = 5.30mm, L17 = 3.0mm, R11 = 0.7mm, R
12 = 0.2 mm and groove angle θ11 = 40 °. In FIG. 7, F is the direction in which rubber flows.

The orientation ratio of the short fibers of the V-ribbed belt produced using the above expansion die is shown in Table 1 below.
Regarding the orientation of the short fibers, the one having the highest orientation rate is defined as the X direction, and the Y direction and the Z direction are sequentially described below. Along with the example of the present invention, a conventional calender (conventional example) and a flat extruded sheet are used. What is used (comparative example) is also shown.

[0049]

[Table 1] In the above embodiment, the inner die 12b of the expansion dies is used.
Although the V-rib portion forming groove 12c is formed on the V-rib portion forming groove 12c, instead of the V-rib portion forming groove 12e, as shown in FIGS.
May be formed on the inner peripheral portion of the outer die 12a.
By doing so, the V rib portions 18a, ... Are molded on the outer peripheral portion of the cylindrical rib rubber tube 18 (FIG. 1).
0).

By the way, the arrangement pitch (for example, L1 = 3.50 mm) of the V rib portion 14b of the rib rubber sheet 14 is the V rib pitch (for example, L of the finished V ribbed belt 1).
11 = 3.56 mm). This is the same in the next vulcanization, but the desired V rib is formed by grinding in the final step. However, if the pitch is misaligned, it cannot be mounted on the molding die well and the V rib is not formed. This is because there will be a problem such as that the shape is deformed.

Therefore, before the rib rubber sheet 14 is attached to the vulcanizing mold 15, the rib rubber sheet 14 has a pitch of 3.
By passing between a 56 mm iron roller and a flat roller, the arrangement pitch of the V rib portions 14b of the rib rubber sheet 14 is set to the V rib pitch of the V ribbed belt 1 (3.5 mm).
6 mm).

<Second Step> The cylindrical rib rubber tube 13 extruded through the outlet of the expansion die 12 is cut in the tube axial direction to form a flat rib rubber sheet 14.

Specifically, the cylindrical rib rubber tube 13 extruded from the expansion die 12 is, as shown in FIG.
It is introduced outside the double cylindrical tube 31. Double cylindrical tube 31
Is supported via the support members 32, 32 so as to be located at a predetermined position. The outer cylindrical member 3 of the double cylindrical tube 31
3, an air pipe 34 is arranged at the center of the tube 3, and the air supplied through the air pipe 34 is supplied to the outer cylindrical member 33.
The air is blown out through the air outlets 33a formed on the outer side surface of the cylindrical rib rubber tube 13 in a floating state with respect to the double cylindrical tube 31 by the feed conveyor 35 and taken by the take-up conveyor 36. It has become. When being taken up by the take-up conveyor 36, the cylindrical rubber tube 13 is cut open in the longitudinal direction by the receiving roller 37 and the cutting round blade roll 38 provided on the supporting members 32, 32 of the double cylindrical tube 31, and the rib rubber sheet 14 is cut.
Is configured to be. The extrusion speed of the cylindrical rib rubber tube 13 is detected at the exit portion of the expansion die 12, and the feed conveyor 35 and the take-up conveyor 36 are driven in synchronization with it.

In this rib rubber sheet 14, the short fibers 14a are oriented in the direction orthogonal to the direction in which the preformed V rib 14b extends.

By the way, the cut rib rubber sheet 14 is used.
Needs to be temporarily wound before forming the V-ribbed belt molded body on the vulcanization mold, which can be performed by a well-known surface winding, but since the rib rubber sheet 14 is unvulcanized, it is wound up. In that case, there is a problem that the sheet is deformed by its own weight or that it sticks between the respective layers of the sheet. Therefore,
As shown in FIG. 2 and FIG. 13, a cover sheet 21 (so-called interwoven cloth or polyester sheet) having a convex portion 21a having a shape corresponding to the groove portion 14c formed between the V rib portions 14b formed on the rib rubber sheet 14 is formed. The convex portions 21a, ...
The rib rubber sheet 14 can be prevented from being deformed by fitting it into the groove portion 14c between the V rib portions 14b, ...

Then, the belt material excluding the rib rubber sheet 14 was added to the cylindrical vulcanization mold 15 (specifically, as shown in FIG.
As shown in FIG. 5, the back canvas 22, the adhesive rubber sheet 23, the core cord 24, and the adhesive rubber sheet 25) are assembled in that order, and then the rib rubber sheet 14 cut to the required length is wound around them, and V Ribbed belt molding 16
(Unvulcanized). At this time, the cut cross section in the thickness direction of the rubber sheet is set to 30 to 45 ° so as to enhance the joint effect by the butt connection.

At the time of molding, the rib rubber sheet 1
Molded by a method that does not give tension to 4 as much as possible,
Further, while the rib rubber sheet 14 is attached, the rib rubber sheet 14 is cut into a required length on the molding die, and the cut surface in the thickness direction is 30 to 40.
The butt joint was designed so that the degree becomes °, and the joint effect is enhanced.

V-ribbed belt molded body 1 is placed on the vulcanization mold 15.
In the state where 6 is molded, as shown in FIG. 14, the convex portion 26 of the rubber mold sheet 26 is provided in the groove portion 14 c of the rib rubber sheet 14.
a is fitted and the rubber type sheet 26 is attached to the rib rubber sheet 14
As is well known, it is wound into a vulcanization can (not shown) and vulcanized and molded by heating and pressurization, and then the molded product 17 after vulcanization is removed from the vulcanization mold 15. Since the rib rubber sheet 14 is cut into a final shape by grinding after vulcanization so that the short fibers are exposed from the rib surface, the concave portion formed between the convex portions 26a, 26a of the rubber type sheet 26 is not formed. , V of the finished V ribbed belt
It is formed to be larger than the rib (see the chain double-dashed line in FIG. 14) by the volume corresponding to the grinding amount.

The rubber type sheet 26 is formed of, for example, butyl rubber, and the convex portion 26a has a rib rubber sheet 14 formed thereon.
Manufactured in a shape corresponding to the groove portion between the V rib portions 14b, ... And wound on the rib rubber sheet after molding. Further, in order to stabilize the rubber type sheet 26, the convex portion 2
As the base sheet portion of 6a, butyl rubber in which short fibers are oriented at right angles to the longitudinal direction of the circumference is used, and the dimensional change is reduced in the arrangement direction (circumferential direction) of the V-rib portion to reduce the longitudinal direction. It has a structure that makes it easy to stretch. It has been confirmed that good results can be obtained by using polymers such as EPT and EPDM in addition to butyl rubber.

Further, when the vulcanized molding product is removed from the vulcanization mold, a rubber mold sheet 26 is attached in order to prevent the belt from being deformed or buckled due to the pulling force applied to the belt at the time of mold release. Do as it is.

As the vulcanization method, the vulcanization can be performed by the following method in addition to the above-described vulcanization can.

(1) A method using a well-known funnel vulcanizer A biaxial cylinder is used, and the surface of the finished V-ribbed belt is opposite to the V-rib of the finished V-ribbed belt, has a slightly smaller mesh shape, and has the same rib pitch, The distance can be changed depending on the belt length.A heat source for vulcanization is passed through one of the two shafts, a molding belt is hung between the two shafts, and a steel belt that is endless is applied from the outside to apply heat. A method of vulcanizing while rotating the biaxial by applying heat from outside.

(2) A method using a well-known press A formed belt is hung between two shafts, and a finished product is formed between the two shafts with a slightly smaller mesh shape as opposed to the V rib of the V-ribbed belt. A mold with the same rib pitch as the V-ribs of the V-ribbed belt is arranged (may be arranged vertically), a flat heat plate is arranged outside the biaxial belt, and a heat source is put in the mold and the heat plate. And pressurize and heat with hydraulic pressure to vulcanize the part of the belt that is in contact with the hot plate, and sequentially feed and bake (vulcanize) it.

(3) Method using a well-known 30% mold A V-ribbed belt molded body is inserted into a mold whose circumferential length is divided into three and which has a similar mold on the surface thereof. A method in which a cylindrical rubber sleeve is covered from the outside and the mixture is heated and vulcanized by a differential pressure using a vulcanizing can.

<Third step> The molded product 17 taken out
, The rib surfaces 17b, ... (Rib side surfaces and rib bottom surfaces) of the V rib portions 17a, ... In which the V ribs are preformed are ground to form predetermined V ribs so that the V ribbed belt has a desired rib shape. Cut out. The V-rib shape is machined
There is no particular limitation, and each rib surface is carved out by the same thickness as shown by the chain double-dashed line A in FIG. 1, and the thickness is changed as shown by the chain double-dashed line in FIG. It can also be carved out.

Here, the grinding is performed in order to cut out the shape of the V-rib having a predetermined shape, and when vulcanizing the short fiber-containing rubber, the phenomenon that short fibers do not appear on the surface of the rubber plate occurs. The purpose of this is to expose the short fibers to the rubber surface to adjust the friction coefficient and impart wear resistance, but since it is preformed, the work of grinding is significantly less than in the conventional method. As compared with the conventional case where the V-rib is ground from the vulcanized flat bottom rubber sheet, the grinding loss of the bottom rubber is reduced by 25 to 30%.

After finishing the grinding, the molded product 17 is cut according to the number of V-ribs required, and a desired V-ribbed belt is obtained.

Next, the test results of the V-ribbed belt according to the present invention and the conventional V-ribbed belt are shown in Tables 2 and 3 below.

[0069]

[Table 2] From Table 2 above, it can be seen that the inventive example has a larger friction coefficient.

[0070]

[Table 3] From the results of the test shown in Table 3 above, it is understood that the inventive examples are superior to the conventional examples in all of abrasion resistance, bending resistance, heat and high load resistance, and high load durability.

Generally, in the case of a V-ribbed belt 101 in which a calendar sheet is used as the bottom rubber (ribbed rubber) of the V-ribbed belt, the tips of the V-ribs 101a, .. When the rib rubber sheet extruded using the expansion die as described above is used as the bottom rubber of the V-ribbed belt, the V-ribbed belt 1 is applied to the small pulley. Even in the bent state, it has been confirmed that the phenomenon that the tips of the V ribs 3, ... Wavy in the left-right direction does not occur (see FIG. 15).

In the former case, since the short fibers are oriented in the lateral direction, a force to inflate acts, but since the action is hindered, the bending stress escapes to the tip of the V-rib. , It is considered that the tip portion is wavy, whereas in the latter, since the orientation of the short fibers is not concentrated in one direction like the former, it is dispersed in other directions,
This is because it is considered that it will easily expand in the lateral direction.

[0073]

The invention according to claim 1 has the following features.
The V-rib is formed by grinding the rib surface of the V-rib portion preformed by extrusion molding into a shape which is made of short fiber compounded rubber and corresponds to the V-rib and is slightly larger than the V-rib. Manufacturing cost can be reduced by saving grinding loss.

In the invention according to claim 2, since the short fibers are oriented in the V-ribs in the belt width direction with an orientation ratio of 30% or more, desired lateral pressure resistance can be obtained and excellent belt characteristics can be obtained. To be

According to the third aspect of the invention, in the first step, the short fibers are oriented in the circumferential direction by an extruder equipped with an expansion die having a V-rib portion forming groove at the outlet portion and correspond to the V-ribs. Further, a cylindrical rib rubber tube having a V rib portion preliminarily formed in a shape slightly larger than the V rib on the outer peripheral portion or the inner peripheral portion is extruded and molded, and vulcanized by using the cylindrical rib rubber tube in the second step. V-ribbed belt molding is molded into the mold, vulcanized, and then
In the third step, the rib surface of the V-rib portion of the V-ribbed belt molded body after vulcanization is ground to form the V-rib, so that the cylindrical rib rubber tube does not interfere with the orientation of the short fibers. , Rib peaks corresponding to the ribs can be formed.

In the invention according to claim 4, the cylindrical rib rubber tube extruded through the outlet portion of the expansion die is incised in the tube axial direction to obtain a flat rib rubber sheet in which short fibers are oriented in the width direction. Since the flat rib rubber sheet is used, the V-ribbed belt molded body can be molded easily and easily on the vulcanization mold.

According to the fifth aspect of the invention, in the second step, prior to the molding of the V-ribbed belt molded body, the rib rubber sheet that has been cut out is fitted with the convex portion of the cover sheet in the groove portion between the V rib portions. Since the cover sheet is wound with the cover sheet, the rib rubber sheet is transported to a place where the V-ribbed belt molded body is molded without being deformed.
It can be transported.

In the second aspect of the present invention, in the second step, the V rib portion of the rib rubber sheet formed on the vulcanization mold has a groove portion between the convex portions which is V pitch at the same pitch as the V rib of the V ribbed belt. Since the rubber type sheet is wound around the ribbed rubber sheet and vulcanized so as to engage with the groove portion between the convex portions of the rubber type sheet having a smaller volume than the rib, V
The rib shape can be accurately and reasonably vulcanized and molded.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a V-ribbed belt.

FIG. 2 is an explanatory diagram of a method for manufacturing a V-ribbed belt.

FIG. 3 is a cross-sectional view of an expansion die.

FIG. 4 is a front view of the same.

FIG. 5 is a perspective view of a part of an extruded cylindrical rib rubber tube.

FIG. 6 is a detailed cross-sectional view of an expansion die.

FIG. 7 is a side view of an extension die.

FIG. 8 is a sectional view of an extension die of another embodiment.

FIG. 9 is a front view of the same.

FIG. 10 is a perspective view of a part of the extruded cylindrical rib rubber tube.

FIG. 11 is an explanatory view of a mechanism for converting a cylindrical rib rubber tube into a rib rubber sheet.

FIG. 12 is a perspective view of a cover sheet.

FIG. 13 is a perspective view showing a state where a cover sheet is applied to the rib rubber sheet.

FIG. 14 is a schematic cross-sectional view showing a state in which a rubber mold sheet is applied to a rib rubber sheet on a vulcanization mold.

FIG. 15 is an explanatory diagram of a V-ribbed belt according to the present invention.

FIG. 16 is an explanatory diagram of a conventional V-ribbed belt.

FIG. 17 is an explanatory diagram of a conventional method for manufacturing a V-ribbed belt.

[Explanation of symbols]

 1 V-ribbed belt 2 Belt base belt 3 V-rib 11 Extruder 12 Expansion die 12a Inner die 12c Outer die 12c V-rib portion forming groove 13,18 Cylindrical rib rubber tube 14 Rib rubber sheet 14b V-rib portion 21 Cover sheet 21a Convex portion

Claims (6)

[Claims] 1. A V-ribbed belt in which a plurality of V-ribs extending in the belt longitudinal direction are formed with respect to a belt base belt, wherein the V-ribs are made of short fiber compound rubber and correspond to the V-ribs. A V-ribbed belt, characterized in that it is formed by grinding the rib surface of a V-rib portion preformed by extrusion molding into a shape slightly larger than the rib. 2. The V-rib, wherein the short fibers are oriented in the belt longitudinal direction, the belt width direction and the belt vertical direction, and the orientation ratio in the belt width direction is 30% or more.
The described V-ribbed belt. 3. A V-ribbed belt manufacturing method for manufacturing a V-ribbed belt in which a plurality of V-ribs extending in the belt longitudinal direction are formed with respect to a belt base using a rubber containing short fibers. An V-rib portion preliminarily formed into a shape corresponding to the V-ribs and slightly larger than the V-ribs by the extruder equipped with an expansion die having a groove at the outlet portion is arranged at the outer peripheral portion or the inner portion. The first step of extruding and molding a cylindrical rib rubber tube having a peripheral portion, and V for a vulcanization mold using the cylindrical rib rubber tube described above.
And a second step of forming a ribbed belt molded body and then vulcanizing the ribbed belt molded body, and a third step of grinding the rib surface of the V rib portion of the V-ribbed belt molded body after vulcanization to form a V rib. A method for manufacturing a V-ribbed belt, comprising: 4. The second step is to cut a cylindrical rib rubber tube along a tube axis direction to form a rib rubber sheet, and mold the V-ribbed belt molded body to a vulcanization mold using the rib rubber sheet. The method for manufacturing the V-ribbed belt according to claim 3. 5. In the second step, prior to the molding of the V-ribbed belt molded body, a cover sheet having a convex portion having a shape corresponding to the groove portion between the V-rib portions formed on the rib rubber sheet is used. The method for manufacturing a V-ribbed belt according to claim 4, wherein the convex portion of the cover sheet is fitted in a groove portion between the V-rib portions and wound. 6. In the second step, the ribbed rubber sheet is wrapped around the ribbed rubber sheet so that the rib portion is engaged with the groove portion between the convex portions of the rubber die sheet, and vulcanized. The method for manufacturing a V-ribbed belt according to claim 3, wherein the groove portion between the convex portions of the sheet has the same pitch as the V-ribbed portion of the V-ribbed belt and has a smaller volume than the V-ribbed portion.