JPH0722976B2 - Toothed endless belt manufacturing method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing a toothed endless belt which is molded from a casting elastomer and has a reinforcing cloth attached to the tooth surface.

(Prior Art) Conventionally, a toothed endless belt molded from a casting elastomer such as polyurethane for casting with a tensile body as a core has a power transmission system that is resistant to dirt due to rubber scraps etc. It is also used as a timing belt in transport systems.

In recent years, in order to reduce noise and improve durability, a reinforcing cloth is placed on the tooth surface formed by a casting elastomer, and a buffer layer is formed between the reinforcing cloth and the tooth section by an impermeable elastomer. A toothed endless belt is known. This belt has been proposed by the present applicant in accordance with Japanese Patent Laid-Open No. 63-214538.

In this belt, since the reinforcing cloth is stopped by the buffer layer, by pressing the liquid casting elastomer injected and filled in the molding die, the tooth portion unevenness of the die is molded. There is an advantage that pressure can be applied to the back surface (the surface on the buffer layer side) of the reinforcing cloth attached to the part to extend the reinforcing cloth along the surface of the uneven portion, and the reinforcing cloth can be formed into teeth at the same time when the belt is formed. is there.

The buffer layer is usually formed by coating the reinforcing cloth with the liquid elastomer several times to seal the reinforcing cloth, but the completeness of sealing is poor and the operation is complicated. On the other hand, a sheet material formed of the same elastomer is thermocompression-bonded to the reinforcing cloth at a temperature equal to or lower than the softening point of the sheet material, whereby an easy and complete buffer layer can be formed.

(Problems to be solved by the invention) Although the toothed belt provided with the reinforcing cloth and the buffer layer facilitates molding and reduces noise,
When a sheet material made of an impermeable elastomer is thermocompression bonded to a reinforcing cloth to form a buffer layer, the adhesiveness between the two is poor and the filamentous fibers of the reinforcing cloth are exposed as they are on the surface. The fact is that the fabric is significantly damaged and the durability is not sufficient.

The present invention has been made in view of the above problems, and when a sheet material formed of an impermeable elastomer is thermocompression-bonded to a reinforcing cloth to form a buffer layer, the adhesive strength between the two is improved and the durability of the belt is improved. It is an object of the present invention to provide a method for manufacturing a toothed endless belt that can dramatically improve

(Means for Solving the Problem) The method for manufacturing a toothed endless belt of the present invention made in order to achieve the above-mentioned object, the inner and outer molds 8 and 9 arranged concentrically, the tooth portion 3,25 Stretchable reinforcing cloths 4, 27, 31 having a buffer layer 7 made of an impermeable elastomer are attached to a mold having concave and convex portions for forming 29, 29, and the reinforcing cloths 4, 27, 31 and others. After mounting the tensile body 6 between the mold and the mold, the liquid casting elastomer 16 is injected into the space 10 between the inner and outer molds 8 and 9 and the elastomer 16 is pressed to reinforce the reinforcing cloth 4,27. In the manufacturing method of the toothed endless belt, which is formed by stretching the 31,31 along the uneven portion of the mold and solidifying the elastomer 16, the reinforcing cloths 4,27,31 are preliminarily used for improving durability and adhesiveness. A buffer layer which is impregnated with an elastomer, and a sheet material 20 formed of an impermeable elastomer is thermocompression-bonded to the impregnated reinforcing cloths 4, 27, 31. It is an arrangement of the invention to be formed.

At this time, a sheet material having a two-layer structure in which a surface layer formed of a low softening point elastomer and a back surface layer formed of a high softening point elastomer are joined and integrated is used. It is effective to perform thermocompression bonding at a temperature above the softening point and below the high softening point.

(Operation) Since the reinforcing cloth according to the present invention is previously impregnated with an elastomer for improving durability and adhesiveness, heat treatment with a sheet material for forming a buffer layer formed of an impermeable elastomer is performed. Adhesiveness by crimping is good, and
Unlike the conventional reinforcing cloth, the filamentous fibers are not exposed as they are on the surface, so that the reinforcing cloth according to the present invention is less likely to be damaged, and the durability and life of the belt are improved.

Also, as the sheet material, a surface layer made of a low softening point elastomer and a back surface layer made of a high softening point elastomer are joined and integrated, and the surface layer is used as the reinforcing cloth side to make the softening point higher than the softening point. When thermocompression-bonded at a temperature below the point, the surface layer melts and is embedded in the texture of the reinforcing cloth, improving the bonding strength between the reinforcing cloth and the buffer layer (that is, the back surface layer of the two-layer sheet material) and reinforcing it. It can contribute to improving the durability of the cloth itself.

(Example) Hereinafter, the manufacturing method of the toothed endless belt of this invention is demonstrated with the manufacturing object.

FIG. 1 shows that tooth portions 3 are integrally formed on the inner peripheral surface side of the belt main body 1 via a land portion 2 at equal intervals in the circumferential direction, and a predetermined elastomer is provided on the surfaces of the tooth portion 3 and the land portion 2. 1 shows an endless belt 5 provided with a impregnated reinforcing cloth 4. The belt body 1 and the tooth portions 3 are made of a casting elastomer material such as casting polyurethane, and a tensile member 6 is embedded in the belt body 1 in a spiral shape. As shown in FIG. 2, a buffer layer 7 made of an impermeable elastomer material such as thermoplastic polyurethane is provided between the tooth portion 3 and the reinforcing cloth 4 with a substantially uniform thickness over the entire surface.

FIG. 3 shows a mold device used for manufacturing the endless belt 5. That is, in FIG. 3, 8 is an inner mold, 9 is an outer mold, and these inner and outer molds 8 and 9 are concentrically provided to form a predetermined space 10 and are separable. An upper lid 11 and a lower lid 12 are detachably provided on the upper and lower ends of the inner and outer molds 8 and 9, respectively, and the upper and lower lids 11 and 12 seal the space 10 between the inner and outer molds 8 and 9. ing. Further, a deaeration hole 13 is formed in the upper lid 11 so as to communicate with the space 10, and an opening / closing screw 14 is detachably screwed into the deaeration hole 13. Reference numeral 15 is a casting container containing a liquid casting elastomer material 16, which is attached to the outer die 9 side through an injection pipe 17 and pressurizes a piston 18 to push the elastomer material 16 from the pipe 17 into the inner and outer die. 8,9
It is possible to cast in space 10. As shown in FIGS. 4 and 5, the endless belt 5 is attached to the outer periphery of the inner mold 8.
An uneven portion 19 for forming the tooth portion 3 is provided all around.

In order to manufacture the endless belt 5, first, a reinforcing cloth is impregnated with an elastomer for improving durability.

As the reinforcing cloth, a highly stretchable woven fabric, a knitted fabric, or a non-woven fabric made of the same fiber, such as synthetic fiber yarn of nylon or polyester, rubber yarn, or the like can be used. As the woven yarn (including knitting yarn), a single yarn, a twin yarn, a twisted yarn, and a crimped yarn can be used. Various woven fabrics such as plain weave, twill weave, satin weave are used.

As the elastomer with which the reinforcing cloth is impregnated, those having a low friction coefficient and good wear resistance are preferable. That is, it is preferable that the one having a large modulus is hard. However, it is necessary to consider the moldability of the reinforcing cloth 4 after impregnation, and an elastomer such as polyurethane having a 100% modulus of 10 to 350 kgf / cm ² (desirably 30 to 250 kgf / cm ² ) is used. The impregnation method is usually carried out by dissolving the resin in a solvent and immersing it in a treatment liquid whose viscosity is adjusted (desirably 50,000 cps or less).

The reinforcing cloth 4 which has been subjected to a predetermined impregnation treatment is then subjected to thermocompression bonding of a sheet material formed of an impermeable elastomer to form a buffer layer 7, which results in a sealing treatment (closing the space of the texture). To be done. As the material of the sheet material, the hardness of the product when manufactured into a durometer A20 to D80 (preferably JIS A40 to durometer D60) is the same as the impregnating melted elastomer such as polyurethane (thermoplastic,
It may be either thermosetting. ) Is used.

FIG. 6 shows an example of thermocompression bonding work for the sheet material 20. The reinforcing cloth 4 and the sheet material 20 are wound around rolls 22 and 23, respectively, and the portions pulled out from the rolls 22 and 23 in the arrow direction are moved up and down. The layers are sequentially laminated by the hot press 21 in a state of being superposed. The sheet material 20 having a thickness of about 0.01 to 2.5 mm is used, and the thermocompression bonding temperature is a softening point of the same material or less (preferably 50 to 15 mm or less of the softening point of the same material when the sheet material is a single material.
0 ° C range).

The sheet material to be thermocompression-bonded is not limited to a single material, but a sheet formed of two layers of elastomers having different softening points can be used. In this case, thermocompression bonding is performed at a temperature of at least the low softening point and less than the high softening point. This is because the elastomer having a low softening point is embedded in the weave, which can contribute to the improvement of adhesiveness and durability. In this case, the difference in softening temperature is preferably 5 ° C. or more in terms of workability.

Next, the reinforcing cloth 4 is cut and endlessly processed into a cylindrical shape by sewing with a sewing machine, adhesion by a heat press, fusion bonding, or the like, and then it is externally fitted to the inner mold 8 of the mold device. The tensile member 6 is spirally wound around the inner mold 8 from the outside of the reinforcing cloth 4. As the tension member 6, synthetic fiber rope such as aromatic polyamide, nylon, polyester, steel wire or the like is used.

When the mounting of the reinforcing cloth 4 and the tensile body 6 on the inner mold 8 is completed, the inner mold 8 is inserted into the outer mold 9 to insert the inner and outer molds 8, 9
Are combined so that a predetermined space 10 is formed. At this time, both ends of the reinforcing cloth 4 in the width direction are bent from the upper and lower ends of the inner mold 8 toward the center side, and both end parts of the reinforcing cloth 4 are bent between the inner mold 8 and the upper and lower lids 11 and 12. Insert and fix.

Then, after heating the entire inner and outer molds 8 and 9 to the curing temperature of the elastomer, the liquid elastomer material 16 in the casting container 15
Is pressurized by the piston 18 with pressure P (2 kgf / cm ² or less),
The space 10 between the inner and outer molds 8 and 9 is filled through the injection pipe 17. The liquid elastomer material 16 preferably has a durometer of A20 to D80 (preferably JIS A70 to 100) when made into a product, and for example, a mixture of a polyurethane polymer and a curing agent is used. The viscosity is adjusted to about 2000 to 4000 cps.

When the space 10 is filled with the elastomer material 16, it flows out from the upper lid 11 and the deaeration hole 13. At the time of the outflow, the opening / closing screw 14 is screwed into the deaeration hole 13 to seal the deaeration hole 13. Then, after this sealing, pressure is applied to the reinforcing cloth 4 via the elastomer material 16 by pressure molding of 10 to 30 kgf / cm ² . Since the reinforcing cloth 4 is blocked by the buffer layer 7 and the elastomeric material 16 does not penetrate, the reinforcing cloth 4 is deformed along the shape of the uneven portion 19 on the outer periphery of the inner mold 8 while expanding together with the buffer layer 7 by pressure, Ensures close contact with the outer peripheral surface of the mold 8 with no gap. Even during this pressurization, since both ends of the reinforcing cloth 4 are fixed between the inner mold 8 and the upper and lower lids 11 and 12, the reinforcing cloth 4 does not move or shift due to the pressurization.

The reinforcing cloth 4 and the buffer layer 7 have an elongation rate (elongation / original length) of 1.4 (preferably 0.8) during pressure molding of the belt.
It is better to stop below. This is because if the amount of deformation is too large, the reinforcing cloth or the like is likely to be damaged, and the sealing may be removed.

When the elastomer material 16 is hardened, the upper and lower lids 11 and 12 are removed, the inner and outer molds 8 and 9 are separated, the molded product is released from the mold, and the molded product is cut into a predetermined product width to form an endless belt 5. Can be manufactured.

In the above description, an example of the impregnation treatment method for the reinforcing cloth is shown.
The present invention is not limited to this, and as shown in FIG. 7, a soft elastomer A having a small modulus (for example, 100% modulus of 10 to 150 is applied to the reinforcing cloth by the primary dipping treatment.
kgf / cm ² of polyurethane), and the reinforcing cloth woven yarn 4a further impregnated by the secondary dipping treatment may be coated with a hard elastomer B (for example, 100% modulus 100 to 350 kgf / cm ² ). . Alternatively, as shown in FIG. 8, the surface layer of the reinforcing cloth may be impregnated with the hard elastomer B by a coating treatment, and the back surface layer on the buffer layer 7 side may be impregnated with the softening elastomer A by a coating treatment. By performing such impregnation treatment, physical properties can be improved without impairing moldability. Further, in the case of FIG. 8, as the elastomer B with which the surface layer is impregnated, one containing a substance that lowers the coefficient of friction (for example, polyurethane containing fluorine resin or silicon resin) or one modified with the same substance (for example, silicone-modified polyurethane) ) Can be used. Although these elastomers have poor adhesiveness, they are embedded in the fibers of the reinforcing cloth and firmly fixed, and can contribute to the reduction of the friction coefficient and the reduction of belt noise. If a large amount of fluororesin, etc. is contained, wear resistance will be reduced.
It is better to stop below.

Further, the structure and shape of the endless belt are not limited to those shown in FIG. 1, and any belt having the reinforcing cloth 4 on the side surface of the belt body 1 can be widely adopted for its production. For example, FIG. 9 shows a symmetrical type endless belt 26 having tooth portions 3 and 25 symmetrically formed on the inner and outer peripheral surfaces of the belt body 1, and FIG. 10 shows an asymmetric endless belt 26 in which inner and outer tooth portions 3 and 25 are displaced in the circumferential direction. Are shown respectively. Further, FIG. 11 shows an endless belt 30 in which the tooth portion 3 is integrally formed on the inner peripheral surface of the belt body 1 and the V-shaped ridge portion 29 is integrally formed on the outer peripheral surface. Also in these cases, the surfaces of the tooth portions 3 and 25 and the ridge portion 29 are covered with the reinforcing cloths 4, 27 and 31.

It is also possible to provide a thin layer of synthetic resin such as silicon or fluorine or an elastomer layer on the surface of the reinforcing cloths 4, 27, 31.
By doing so, the friction coefficient of the surface of the reinforcing cloths 4, 27, 31 can be arbitrarily changed, and the field of use of the belt is expanded.

Next, specific examples will be described.

(1) Nylon fiber woven cloth was used as a reinforcing cloth and impregnated with polyurethane having 100% modulus of 150 kgf / cm ² by dipping treatment. The viscosity of the dipping treatment liquid was 3000 cps.

(2) As Example 1, a 0.4 mm-thick polyurethane sheet (hardness JIS A85) was placed on the back surface of the impregnated reinforcing cloth at 120 ° C.
Then, the buffer layer was formed by thermocompression bonding and also as a sealing treatment. At this time, as a conventional example, a buffer layer was formed in the same manner for a reinforcing cloth similar to that of the example but not impregnated.

Further, as Example 2, each thickness of the front surface layer and the back surface layer is 0.
3mm 2-layer polyurethane sheet (softening temperature of surface layer 100
The buffer layer was formed by arranging the surface layer having a back surface layer softening temperature of 150 ° C.) so as to come into contact with the back surface of the impregnated reinforcing cloth and thermocompression bonding at 120 ° C.

(3) After the reinforcing cloths having the buffer layers of Examples 1 and 2 and the conventional example are endlessly processed into a tubular shape, they are attached to an inner mold as shown in FIGS. After winding the polyamide fiber rope in a spiral shape, it was inserted into an outer mold to form a molding mold.

After heating the mold to about 110 ℃, the hardness after curing is JIS A85
Liquid polyurethane for casting (including curing agent. Viscosity 20
(00-4000 cps) was cast, and after sealing, pressure molding was performed under the molding conditions of 110 ° C. and 20 kgf / cm ² , and this state was maintained for 60 minutes.

After the molding was completed, the molded product was released from the mold and cut into a predetermined width to obtain a toothed endless belt.

(4) Using the belts of Examples 1 and 2 and the conventional example, the belt performance was examined in the following region.

Measurement of friction coefficient μ Take a sample piece of a certain length from the belt and use a steel plate (material SS 4
1, the surface roughness Rmax25 S) is placed so that the tooth surface abuts, a constant load W is applied to the belt piece to pull it, and the force F required when moving at a speed of 1 cm / sec is obtained. μ = F / W
I asked.

Abrasion resistance evaluation A pair of drive-side pulley and load-side pulley are provided with standard mounting tension to span the belt, and a constant load (brake) is applied to rotate the drive pulley at 3000 rpm (belt peripheral speed 2.6 m / sec). Then, after a lapse of a certain period of time, the weight of the belt was measured, and the difference (weight reduction) from the initial value was obtained and used as the evaluation standard. The belt tester was also used for the following tests.

Measurement of jumping torque The belt tension was set to 1/2 of the standard installation tension, the belt was run, and the transmission torque (jumping torque) immediately before jumping was performed by changing the load.

Measurement of maximum transmission torque The belt was run with standard mounting tension, and the maximum torque that can be transmitted was measured by changing the load.

Durability evaluation After applying a standard mounting tension and running the belt for a certain period of time under a load near the jumping torque, the damage (defect) state due to the abrasion of the belt teeth was examined, and this was used as the evaluation standard.

Measurement of noise A belt was run under a constant load with a standard mounting tension, and a noise shape was provided at a position facing the running surface of the belt and separated by 30 cm from the running surface, and the running noise was measured.

(5) Table 1 shows the measurement results. The numbers in the table are indexed using the belt of Example 1 as a reference (index 100).

As shown in Table 1, the friction coefficient of Examples 1 and 2 was higher than that of the conventional example, and as a result, the noise was doubled, but the wear resistance and durability were 10 times or more. Improved. Further, also in Examples, Example 2 in which the buffer layer is formed of the two-layer sheet material is significantly improved in wear resistance and durability as compared with Example 1.

(Effects of the Invention) As described above, in the method for manufacturing the toothed endless belt of the present invention, since the reinforcing cloth is impregnated with the elastomer for improving the adhesiveness and the durability, the buffer layer is formed together with the sealing treatment. Although the thermal adhesiveness to the sheet material of No. 1 was improved and the noise was slightly increased, the durability was dramatically improved to 10 times or more compared with the conventional belt.

In addition, by using a sheet material having a two-layer structure and thermocompression-bonding the surface layer formed of the low softening point elastomer on the reinforcing cloth side at a temperature of at least the low softening point and less than the high softening point,
The surface layer of the sheet material can be embedded in the texture of the impregnated reinforcing cloth, and the improvement of the adhesiveness and the improvement of the impregnation rate of the reinforcing cloth can be combined to significantly improve the durability.

[Brief description of drawings]

FIG. 1 is a perspective view of a belt showing an embodiment of the present invention, FIG. 2 is a sectional view of the belt, FIG. 3 is a sectional view of the mold device, and FIG.
FIG. 5 is a sectional view of the main part of the mold, FIG. 5 is a plan view of the same section, and FIG.
The figure is an explanatory view showing the thermocompression bonding state of the reinforcing cloth and the sheet material, FIG. 7 is an enlarged cross-sectional view of the weaving yarn of the reinforcing cloth impregnated by the primary and secondary dipping treatments, and FIG. 8 is the surface layer. And a partial cross-sectional view of the reinforcing cloth with different impregnation treatment on the back surface layer,
9 to 11 are perspective views of belts showing other embodiments. 1 …… Belt body, 2 …… Land part, 3,25 …… Tooth part, 4,
27,31 …… Reinforcement cloth, 5,26,30 …… Endless belt, 6 …… Tensile body, 7 …… Buffer layer, 8 …… Inner mold, 9 …… Outer mold, 10…
… Space, 11 …… Upper lid, 12 …… Lower lid, 16 …… Liquid casting material, 19 …… Uneven part, 20 …… Sheet material.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display area B29K 105: 22 B29L 29:00

Claims (2)

[Claims] 1. Inner and outer molds (8) arranged concentrically,
Of (9), a stretchable reinforcing cloth having a buffer layer (7) made of an impermeable elastomer in a mold having tooth portions (3), (25), and (29) forming concavo-convex portions. (4),
(27), (31) are attached and the reinforcing cloths (4), (27),
After mounting the tensile body (6) between the (31) and another mold,
The liquid casting elastomer (16) is injected into the space (10) between the inner and outer molds (8) and (9), and the elastomer (16) is pressed to reinforce the reinforcing cloths (4), (27), ( In the manufacturing method of the toothed endless belt in which 31) is stretched to be molded along the uneven portion of the mold and the elastomer (16) is solidified, the reinforcing cloths (4), (27) and (31) are preliminarily durable. Buffer layer by impregnating the reinforcing material (4), (27), (31) impregnated with an elastomer for improving the adhesiveness and adhesiveness and thermocompression-bonding the sheet material (20) formed of the impermeable elastomer (7) is formed, The manufacturing method of the toothed endless belt characterized by the above-mentioned. 2. The sheet material (20) has a surface layer formed of a low softening point elastomer and a back surface layer formed of a high softening point elastomer, which are joined and integrated, and the surface layer is made into a reinforcing cloth side to have a low softening point. The method for producing a toothed endless belt according to claim 1, wherein thermocompression bonding is performed at a temperature of not less than the point and less than the high softening point.