JP2003048256A - Method for manufacturing transmission belt - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a transmission belt such as a V-ribbed belt, a double-ribbed belt or the like which can recycle a scrap rubber, which has an excellent side pressure resistance and a reduced noise at a traveling time. SOLUTION: The method for manufacturing the transmission belt comprises a first step of molding a short fiber-oriented rubber sheet 18 in which short fibers are oriented in a widthwise direction, a second step of notching ribbed grooves 19 extended in a longitudinal direction on the sheet 18 by a pair of ultrasonic cutters 31 and fluffing the fibers 22 from surfaces of the grooves 19, a third step of winding a belt constituting member and the short fiber oriented rubber sheet 18 cut in a predetermined length on a cylindrical mold 50, molding a belt molding, and further winding a sheet-like rubber mold 55 so that a protruding part 56 of the mold 55 is engaged with the grooves 19 of the short fiber oriented rubber sheet, and a fourth step of vulcanizing the belt molding and finishing the molding to a belt sleeve.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a power transmission belt, and more specifically, it is possible to reuse scrap rubber, has excellent lateral pressure resistance, and reduces noise during running, such as a V-ribbed belt and a double-ribbed belt. The present invention relates to a method for manufacturing a power transmission belt.

[0002]

2. Description of the Related Art In a V-ribbed belt, a core wire is embedded in an adhesive rubber layer, and a cover canvas is laminated on the adhesive rubber layer.
A plurality of ribs are provided below the adhesive rubber layer. This V-ribbed belt is widely used instead of the V-belt as a power transmission for driving an auxiliary machine such as an air compressor or alternator of an automobile.

This belt is obtained by producing a belt sleeve in which a canvas, an adhesive rubber layer, a cord made of a cord, and a compression rubber layer are integrally laminated by vulcanization, and a rib groove is ground on the compression rubber layer by a grinder wheel. Was given,
Aramid short fibers are projected from the rib groove surface of the compressed rubber layer. When this is suspended and run on a pulley for driving auxiliary equipment such as an air compressor or alternator of a car,
The protruding aramid short fibers were interposed between the belt and the pulley to prevent noise and abnormal noise when the belt was running. However, in this manufacturing method, rubber scraps are generated when the rib groove is ground, and early improvement is desired in terms of environmental problems.

For this reason, recently, as a belt manufacturing method for reducing the amount of material waste as much as possible, Japanese Patent Laid-Open Publication No. HEI-1 has been proposed.
No. 0-86236, a belt sleeve having a buffer layer and a compression layer is produced, the belt sleeve is placed in a mold, the rib portion is marked and then vulcanized, and the rib portion is thin so as to expose the fiber. A method of removing the surface layer is disclosed.

Further, Japanese Patent Laid-Open No. 8-74936 discloses that
A short rib is oriented by an extruder equipped with an expansion die at the outlet to extrude a cylindrical rib rubber tube having a V rib portion on the outer or inner circumference, which is incised to form a rib rubber sheet, which is wound around a mold. It is described that a belt molded body is obtained, which is vulcanized and the rib surface is ground to form a V-ribbed belt.

Further, in Japanese Unexamined Patent Publication No. 5-345370, after a vulcanized belt sleeve is suspended and rotated by a pair of supporting rollers, a knives having a plurality of blades inclined in the same direction are used to make a cut. , A method of making a V-groove by making a notch with another blade having a plurality of blades.

[0007]

However, in the method in which the belt sleeve is installed in a mold having an engraved inner surface and the ribs are engraved and then vulcanized, short fibers are contained in the rubber. In addition, under normal temperature and pressure conditions, the rib portion may not be sufficiently imprinted, so the level of these conditions was raised to give a large heat history to the rubber. Also,
Since the belt sleeve is installed inside the mold and the inner pressure is applied to press against the inner wall of the mold, it is difficult to remove the belt sleeve after molding. In addition, since the short fibers are oriented in a curved state in the rib portion of the obtained belt, the lateral pressure resistance of the belt was insufficient.

Further, when a cylindrical rib rubber tube is extruded from the expansion die and cut into a rib rubber sheet to be used, a short fiber circle is formed in order to form a V-shaped rib portion with the expansion die. Disturbances in the circumferential direction were generated, and the short fibers were oriented in a curved state in the rib portion of the obtained belt, and the lateral pressure resistance of the belt was similarly lacking. In addition, it is necessary to increase the pressing force of the extruder, the internal heat generation is increased, and the rubber hardness is likely to be increased, which causes a problem of impairing the fluidity.

Further, in the method of cutting into the V-groove using a blade, it is difficult to reuse scrap rubber because the vulcanized belt sleeve is cut, and short fibers are cut near the root on the surface of the V-groove. Since the short fibers are not easily interposed between the belt and the pulley, noise or abnormal noise may occur when the belt is running.

The present invention has been made in view of the above-mentioned circumstances, and addresses the problem. It is possible to reuse scrap rubber.
Further, the present invention provides a method for manufacturing a transmission belt such as a V-ribbed belt and a double-ribbed belt which has excellent lateral pressure resistance and reduces noise during traveling.

[0011]

That is, the invention according to claim 1 of the present application is such that an adhesive rubber layer in which a core wire is embedded along the longitudinal direction of the belt and a rib adjacent to the adhesive rubber layer and extending in the longitudinal direction of the belt. In a method for manufacturing a transmission belt having a portion, a first step of forming a short fiber oriented rubber sheet in which short fibers are oriented in the width direction, and a rib groove extending in the longitudinal direction on the short fiber oriented rubber sheet by a pair of ultrasonic cutters. And the second step of fluffing the short fibers from the rib groove surface, and winding the short fiber-oriented rubber sheet cut into a predetermined length and the belt constituent member on the cylindrical molding die to form a belt molding. The third step of winding the die so that the convex portion provided on the outer die fits into the rib groove of the short fiber oriented rubber sheet, and the belt molded body is vulcanized to form a belt sleeve. 4 and steps in the manufacturing method of the driving belt consisting of.

In the present invention, particularly in the second step, an ultrasonic cutter reduces the resistance at the time of processing to improve the cutting performance, and ultrasonic vibration vibrates the surfaces of the rib grooves to cause short fibers to be generated due to friction between the cutter and rubber. It loosens and causes fuzz,
The unvulcanized short fiber mixed rubber that has been ground has a great effect that it can be reused. Further, in the vulcanization of the fourth step, fluffed short fibers remain on the rib groove surface of the belt sleeve after vulcanization. Therefore, it is not necessary to grind the rib groove surface layer, and the number of steps is reduced. The manufacturing cost can be reduced.

The invention according to claim 2 of the present application is a method for manufacturing a transmission belt in which the cutting speed of the rib groove is 5 to 25 mm / sec. Within this range, short fibers are sufficiently fluffed from the rib groove surface. be able to.

In the invention according to claim 3 of the present application, the outer mold used in the third step is a sheet-shaped rubber mold and has at least one convex portion on one surface.

The invention according to claim 4 of the present application is a rubber composition in which the rubber of the short fiber oriented rubber sheet is an ethylene-α-olefin elastomer.

[0016]

DETAILED DESCRIPTION OF THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings. Hereinafter, FIG. 1 shows a first step of forming an extruded cylindrical molded body into a linearly cut short fiber oriented rubber sheet, and a second step of cutting into the short fiber oriented rubber sheet with an ultrasonic cutter to provide a rib groove. It is a schematic diagram of a process.

In the first step and the second step, the extruder 1 is used. This apparatus 1 has a cylinder 2 for kneading rubber containing short fibers by rotation of an extrusion screw 3 and an extruder 6 composed of a connecting pipe 4 for moving a rubber 7 containing short fibers to the next step. The short fiber-mixed rubber 7 extruded from 6 is passed through the gap between the inner die 9 and the outer die 10 to impart a gradually increasing circumferential direction toward the discharge port 11 to make the short fibers circumferential. The annular expansion die 15 for extruding the cylindrical molded body 13 oriented in the direction, and the short fiber oriented rubber sheet 18 while incising the cylindrical molded body immediately after being extruded.
Further, a cutting means 20 and a moving means 45 for moving the short fiber oriented rubber sheet 18 are provided.

The cylinder 2 of the extruder 6 has an extrusion screw 3 rotatably accommodated therein, a rubber compound containing short fibers is put in from a raw material charging port 17, and the short screw and the rubber are mixed by the rotation of the extrusion screw 3. Knead to mix short fiber rubber 7
To At this time, air generated in the cylinder 2 and the gas generated from the rubber compound are discharged from an exhaust port (not shown). The temperature of the cylinder 2 changes according to the rubber type,
Normally, the temperature is adjusted to 40 to 100 ° C., and the short fibers and the rubber are heated to a temperature at which they can be easily mixed to be thermoplasticized, so that they are easily extruded. Further, the kneading time in this case is adjusted so that the vulcanization of the rubber does not proceed. The connecting pipe 4 guides the short fiber mixed rubber 7 to the annular expansion die 15.

The annular expansion die 15 includes the inner die 9 and the discharge port 11
The diameter is gradually expanded toward the shape of a cone to be housed in the outer die 10, and a gap having a predetermined thickness is provided between the inner die 9 and the outer die 10. The short fiber-mixed rubber 7 is extruded into a cylindrical molded body 13 in which the short fibers are oriented in the circumferential direction while gradually expanding toward the discharge port 11 in the circumferential direction.

The annular expansion die 15 is vertically fixed to the extruder 6 arranged horizontally, and the cylindrical molded body 13 extruded from the discharge port 11 is placed so as to resist gravity, so that it has a cylindrical shape. The molded body 13 is not deformed by gravity and can be extruded in a state where the dimensional change is small. Further, the annular expansion die 15 arranged in the vertical direction is hard to bend due to the weight of the inner die 9, and the gap between the inner die 9 and the outer die 10 is kept constant,
As a result, the cylindrical molded body 13 with a small amount of thickness deformation can be finished.

The flow passage widths of the inner die 9 and the outer die 10 are
The inner die 9 is connected to the extruder 6 through the root portion 23 to the discharge port 1
It becomes uniform up to 1 and smoothly flows in the longitudinal direction D without braking the extrusion of the cylindrical molded body 13, and the cylindrical molded body 13 having a uniform thickness without internal distortion is finished.

The shape of the inner die 9 becomes a factor that affects the magnitude of the shearing force. The taper angle θ at which the diameter gradually expands from the root portion 23 toward the discharge port 11 is 30 ° ≦ θ <
90 °, the rubber channel inlet is 20 to 60 mm, the rubber channel inlet / outlet is 100 to 440 mm, and the ratio of expansion (rubber channel inlet / outlet / rubber channel inlet) is 1.5 to 1
Set to 2.5. If it is less than this set range, the stretching in the circumferential direction in the vicinity of the discharge port 11 of the inner die 9 is small, and the short fibers are difficult to be oriented in the circumferential direction in the inner and outer layers of the thick cylindrical molded body 13. On the other hand, when the value exceeds this setting range, the circumferential expansion becomes too large, and when the extrusion pressure is poor, the cylindrical molded body 13 is likely to tear.

In order to suppress internal heat generation of the short fiber mixed rubber 7 between the inner die 9 and the outer die 10, a cooling device (not shown) for circulating cooling water may be provided inside the inner die 9. In the cooling device, cooling water is introduced from the outside of the inner die 9 and passed through a passage provided in the inner die 9 by a pump to be discharged from the inner die 9 and circulated.

In the cutting means 20, the cylindrical molded body 13 immediately after being extruded by the cutting member 21 is cut along the extrusion direction to form the short fiber oriented rubber sheet 18. The cutting member 21 is a blade such as a cutter or a knife, or a laser knife or an ultrasonic cutter.

The short fiber oriented rubber sheet 18 is moved at a constant speed by the driving roll 25 via the guide rolls 24, 24, and the liner 42 such as canvas is laminated on the winding roll 41 and wound up.

Needless to say, the short fiber oriented rubber sheet 18 does not have to be produced by the above-mentioned extrusion device 1, but can be produced by sheeting a rubber containing short fibers kneaded with a Banbury mixer with a calender roll.

In the second step, as shown in detail in FIG. 2, FIG. 3 and FIG. 4, a set of ultrasonic vibrator 32 is attached to the blade 31 on the moving short fiber oriented rubber sheet 18. The ultrasonic cutter 30 is fixed while changing its angle, and grinds a single rib groove 19. The inclination angle of the blade portion 31 corresponds to the angle of the rib groove 19.

In order to grind the multiple rib grooves 19 at the same time, a pair of ultrasonic cutters 30 are arranged with their positions displaced in the longitudinal direction. The ultrasonic cutter 30 can cut smoothly even if it is a difficult cut with a large processing resistance, by applying ultrasonic vibration, it can be cut smoothly.
For this reason, as shown in FIG. 5, the short fibers 22 are loosened on the surface of the rib groove 19 and fluffing occurs and is projected. The ultrasonic transducer 32 used here is, for example, a PZT electrostrictive transducer,
Speed 20,000-40,000 times / sec, Amplitude 20-1
It is 00 μm.

The moving speed of the short fiber oriented rubber sheet 18 is
When the ultrasonic cutter 30 is fixed, the cutting speed is substantially reached. This cutting speed range is 5 to 25 mm /
When set to seconds, the short fibers are loosened on the surface of the rib groove 19 and fluffing easily occurs. That is, if it is less than 5 mm / sec, the productivity is poor and the frictional heat becomes too large to burn the rubber. On the other hand, if it exceeds 25 mm / sec, the short fibers 22 on the surface of the rib groove 19 are cut at the root to make a stump. It does not become loose and fluffing does not occur easily.

Of course, in the case of the present invention, after the short fiber oriented rubber sheet 18 cut to a predetermined length is installed and fixed, the ultrasonic cutter 30 is set in the longitudinal direction of the short fiber oriented rubber sheet 18, that is, at right angles to the short fibers. One or a plurality of rib grooves 19 can be cut by moving in the direction of 5 to 25 mm / sec.

In the third step, as shown in FIG. 6, a synthetic fiber such as polyester, nylon, aramid, vinylon or a natural fiber such as cotton is laid on a cylindrical molding die 50, a plain weave canvas made of a mixture of these fibers, A cover cloth 51 made of a knitted fabric or the like in a tubular shape by a sewing machine joint, an adhesive rubber sheet 52, a core wire 53 made of a cord of polyester fiber, aramid fiber, etc. The rib groove 19 cut
The short-fiber oriented rubber sheet 18 with a mark is wound to form a belt molded body 58 for a V-ribbed belt.

Then, the convex portion 56 of the sheet-shaped rubber die 55.
While fitting into the rib groove 19 of the short fiber oriented rubber sheet, the vulcanized sheet-shaped rubber die 55 is wound around the short fiber oriented rubber sheet 18, the abutting portion of the rubber die 55 is joined with an adhesive tape, and the jacket is fitted. After the insertion, the belt sleeve is manufactured by vulcanization by a usual method. On the surface of the rib groove 19 of the vulcanized belt sleeve, short fibers are released and fluffing is maintained. Therefore, it is not necessary to remove the thin surface layer of the rib groove 19 by the grinding wheel to fluff the short fibers. In the case of the present embodiment, the sheet-shaped rubber die 55 becomes scrap when the number of times of use increases, so a metal split die may be used instead.

The short fiber-containing rubber includes natural rubber, butyl rubber, styrene-butadiene rubber, chloroprene rubber, ethylene-propylene rubber, alkylated chlorosulfanated polyethylene, hydrogenated nitrile rubber, hydrogenated nitrile rubber and unsaturated carboxylic acid metal. Ethylene-α consisting of mixed polymer with salt, ethylene-propylene rubber (EPR) and ethylene-propylene-diene monomer (EPDM)
-Rubber materials, such as olefin elastomers, alone or in mixtures thereof. Examples of the diene monomer include dicyclopentadiene, methylene norbornene, ethylidene norbornene, 1,4-hexadiene, cyclooctadiene and the like.

The rubber is made of aramid fiber, polyamide fiber, polyester fiber, cotton or the like, and the length of the fiber varies depending on the type of fiber, but short fibers of about 1 to 10 mm are used, for example, aramid fiber. And 3 to 7m
m, polyamide fiber, polyester fiber, and cotton, those having a diameter of about 5 to 10 mm are used. The addition amount is 10 to 40 parts by mass with respect to 100 parts by mass of rubber. Furthermore, a softening agent, a reinforcing agent made of carbon black, a filler, an antioxidant, a vulcanization accelerator, a vulcanizing agent and the like are added to the rubber of the present invention.

As the above-mentioned softening agent, a general plasticizer for rubber, for example, phthalates such as dibutyl phthalate (DBP) and dioctyl phthalate (DOP), adipates such as dioctyl adipate (DOA), dioctyl sebacate (DOS). ) And the like, phosphates such as tricresyl phosphate, etc., and general petroleum-based softeners.

[0036]

EXAMPLES Next, specific examples of the method for manufacturing the transmission belt will be shown below. Examples 1 to 3 and Comparative Examples 1 to 2 Using EPDM rubber compounds shown in Table 1, short fibers were preliminarily added to the rubber by an open roll and kneaded, and then the kneaded master batch was once discharged, and this was kept at room temperature. Cool down. This masterbatch and other compounding agents were put into the cylinder of the apparatus for producing a rubber molding containing short fibers shown in FIG. 1, and short fibers were mixed by rotating an extrusion screw.

[0037]

[Table 1]

Then, depending on the dimensional conditions of the annular expansion die shown in Table 2 and the temperature conditions of the extruder, the short fiber mixed rubber is gradually expanded toward the discharge port in the circumferential direction, and a shearing force is applied to the cylinder to form a cylinder. The shaped body was extruded and cut into a short fiber oriented rubber sheet.

[0039]

[Table 2]

Subsequently, the short fiber oriented rubber sheet is cut into a predetermined length, which is set on a moving table and the speed is 5 to 50 mm /
While moving in the range of seconds, a set of fixed ultrasonic cutters (ultrasonic vibration speed 22,000 times / second, amplitude 70μ)
m, a PZT electrostrictive vibrator as a vibrator, an arrow-shaped material SKH as a blade portion, and a thickness of 0.6 mm) to cut a single rib groove, and this operation is repeated to form a plurality of short fiber oriented rubbers with rib grooves. I made it into a sheet. Table 3 shows the relationship between the moving speed (cutting speed) of the obtained short fiber oriented rubber sheet and the loosened state of the short fibers on the rib groove surface.

Then, a V-ribbed belt was manufactured. In this method, first, two plies of rubber-coated cotton canvas are laminated on a cylindrical molding die, and an adhesive rubber sheet, a core wire made of polyester fiber rope, an adhesive rubber sheet, and a short-fiber oriented rubber sheet with a rib groove are wound around. It was made into a belt molded body. The adhesive rubber layer has a rubber composition obtained by removing the cut yarn from the rubber composition shown in Table 1.

While fitting the convex portion of the sheet-shaped rubber die into the rib groove of the short fiber oriented rubber sheet, the sheet-shaped rubber die is wound around the short fiber oriented rubber sheet, and the abutting portion of the rubber die is joined by an adhesive tape. Then, the jacket was inserted and then vulcanized by a usual method. After vulcanization, the jacket was pulled out, the belt sleeve was released from the mold, the adhesive tape was removed, and the sheet rubber mold was peeled off. The short fiber oriented rubber sheet used here was one provided with rib grooves at a moving speed of 15 mm / sec.

On the surface of the rib groove of the belt sleeve, short fibers were unraveled and fluffed and protruded. Therefore, the belt sleeve was cut into individual belts to produce V-ribbed belts. The obtained V-ribbed belt is a K-shaped 3-ribbed belt having a length of 975 mm according to the RMA standard, and has a rib pitch of 3.56 mm, a rib height of 2.0 mm, a belt thickness of 4.30 mm, and a rib angle of 40 °.

Comparative Example 3 A cylindrical molded body was extruded using an annular expansion die in the same manner as in Example 1 and cut into a short fiber oriented rubber sheet. Then, while moving the short fiber oriented rubber sheet at 5 mm / sec, a single rib groove is cut by a blade portion (arrow shape, material SKH, thickness 0.6 mm) that does not give ultrasonic waves, and a short rib groove is formed. A fiber oriented rubber sheet was finished. On the surface of the rib groove of the sleeve, short fibers were cut from the root and were not loosened to cause fluffing.

[0045]

[Table 3]

From these results, when an ultrasonic cutter was used, the short fibers on the surface of the rib groove were loosened and fluffing occurred in the cutting speed range of 5 to 25 mm / sec, but the cutting speed was 30 mm / sec. At 50 mm / sec, the short fibers on the surface of the rib groove were cut at the root and disentangled, and no fluffing occurred. In addition, the cutting speed is 5m for cutters without ultrasonic waves.
Even at m / sec, the short fibers on the surface of the rib groove were cut at the root and disentangled, and no fluffing occurred.

[0047]

As described above, in the invention described in each of the claims of the present application, in particular, a rib groove extending in the longitudinal direction is cut into the short fiber oriented rubber sheet by a pair of ultrasonic cutters, and short fibers are fluffed from the rib groove surface. Therefore, the ultrasonic cutter reduces resistance during processing to improve cutting performance, and the rib groove surface causes fluffing due to loosening of short fibers due to friction between the cutter and rubber due to ultrasonic vibration.
And the unvulcanized short fiber mixed rubber that has been ground can be reused,
Further, in vulcanization, fluffed short fibers remain on the rib groove surface of the belt sleeve after vulcanization, and therefore, it is not necessary to grind the rib groove surface layer, which reduces man-hours and reduces manufacturing cost. There is a great effect that it can reduce.

[Brief description of drawings]

FIG. 1 is a first step of forming an extruded cylindrical molded body into a linearly cut short fiber oriented rubber sheet, and a second step of cutting into the short fiber oriented rubber sheet with an ultrasonic cutter to provide a rib groove. FIG.

FIG. 2 is a plan view of FIG. 1 viewed from the AA direction.

FIG. 3 is a sectional view taken along line BB of FIG.

FIG. 4 is a front view of an ultrasonic cutter.

FIG. 5 is a cross-sectional view of a short fiber oriented rubber sheet with rib grooves.

FIG. 6 is a cross-sectional view of a state where a belt molded body for a V-ribbed belt is manufactured on a cylindrical molding die.

[Explanation of symbols]

6 extruder 13 Cylindrical compact 15 Ring expansion die 18 Short fiber oriented rubber sheet 19 rib groove 22 Short fiber 30 ultrasonic cutter 31 blade 32 ultrasonic transducer

Claims (4)

[Claims] 1. A method for manufacturing a transmission belt having an adhesive rubber layer in which a core wire is embedded along the longitudinal direction of the belt, and a rib portion adjacent to the adhesive rubber layer and extending in the longitudinal direction of the belt. A first step of forming a short fiber oriented rubber sheet oriented in a vertical direction, and a second step of cutting a rib groove extending in the longitudinal direction into the short fiber oriented rubber sheet with a pair of ultrasonic cutters and fluffing short fibers from the rib groove surface. A belt molding member is formed by winding a belt constituent member on a cylindrical molding die, and the above-mentioned short fiber oriented rubber sheet cut to a predetermined length to form a belt molded body, and a convex portion provided on the outer die is further provided with a short fiber oriented rubber. A transmission bell comprising a third step of winding the mold so as to fit into a rib groove of a sheet and a fourth step of vulcanizing the belt molded body to finish it into a belt sleeve. The method of production. 2. The method for manufacturing a transmission belt according to claim 1, wherein the cutting speed of the rib groove is 5 to 25 mm / sec. 3. The method for manufacturing a transmission belt according to claim 1, wherein the outer mold used in the third step is a sheet-shaped rubber mold and has at least one convex portion on one surface. 4. The method for producing a power transmission belt according to claim 1, wherein the rubber of the short fiber oriented rubber sheet is a rubber composition using an ethylene-α-olefin elastomer.