JP2008100455A - Method of manufacturing composite rubber tape and method of manufacturing rubber tube - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a composite rubber tape which can be suitably used as a material for forming the entirety of a rubber tube of an outwardly conical trapezoidal shape or an external surface rubber layer, and a manufacturing method of the rubber tube using the composite rubber tape. <P>SOLUTION: This method of manufacturing the composite rubber tape is to obtain the composite rubber tape 3 with a short fiber 1 orientated in a longitudinal direction A by extruding a composite rubber obtained by mixing an unvulcanized rubber with the short fiber 1, through a slit-like extrusion orifice 6 formed in an extruder 2. The extrusion orifice 6 is of an arc-like slit shape. The tape width can be changed while inhibiting a thickness variation of the composite rubber tape 3 by further stretching the composite rubber tape 3, extruded from the extrusion orifice 6, in the longitudinal direction A. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing a composite rubber tape in which short fibers are oriented in the length direction, and more particularly to a method for producing a composite rubber tape having a substantially constant thickness and adjustable tape width.

  Conventionally, abrasion resistance is required for a rubber cylinder such as a pumping tube of a squeeze pump. As a rubber cylinder with improved wear resistance, a rubber tube is known in which the outer rubber layer of the pumping tube is composed of a composite rubber in which rubber and short fibers are mixed (Patent Document 1). This rubber cylinder has the advantage that the short fibers suppress wear of the outer rubber layer.

  In order to form the outer rubber layer of the cylindrical rubber cylinder with the above composite rubber, a sheet in which short fibers are arranged in the longitudinal direction is wound around the pumping tube body before forming the outer rubber layer, or Patent Document 2 As shown in FIG. 2, there is known a method of applying a composite rubber extruded from a crosshead type extruder to a tube body.

  By the way, as a cylinder made of rubber such as a pumping tube, the one having a truncated cone shape is generally used in addition to the cylindrical shape. In the truncated cone-shaped rubber cylinder, the method of forming the outer rubber layer by wrapping the rubber sheet around the cylindrical main body before forming the outer rubber layer causes wrinkles or uneven thickness. There has been a problem that characteristics such as wear resistance of the cylindrical body vary from place to place. Further, there has been a problem that the crosshead type extruder can be applied only to a cylindrical one.

In order to form the outer rubber layer without causing wrinkles on the surface of the cylindrical body having a truncated cone shape, a rubber sheet cut into a tapered strip is used as described in Patent Document 3, and this is used. It is also conceivable to wind the wire around the tubular body in a spiral shape.
Japanese Utility Model Publication No. 4-84780 JP 2000-297533 A JP-A-11-58544

  However, in the method using a rubber sheet cut into a tape-shaped strip, after processing the composite rubber into a sheet shape, the rubber sheet is cut, and the cut rubber sheet is wound around a mandrel in a spiral shape. There is a problem that a process is required, which is complicated and unsuitable for mass production.

  Accordingly, the present invention provides a composite rubber tape that can be suitably used as a material for forming the outer rubber layer of a rubber cylinder having an outer shape of a truncated cone, and that can vary the tape width with little variation in thickness. Another object of the present invention is to provide a method of manufacturing a rubber cylinder having a truncated cone shape using the composite rubber tape.

  In order to solve the above-mentioned problems, the present invention provides a composite rubber obtained by mixing unvulcanized rubber and short fibers by extruding it from a slit-like extrusion port formed in an extrusion device in the length direction. A method of manufacturing a composite rubber tape in which short fibers are oriented, wherein the extrusion port has an arcuate slit shape, and the composite rubber tape extruded from the extrusion port is further pulled in the length direction, thereby increasing the thickness of the composite rubber tape. The tape width is changed while suppressing the change.

  According to the said structure, it becomes possible to change a tape width, suppressing the change of the thickness of a composite rubber tape by changing the tensile force (drawing speed) of a composite rubber tape. That is, in an unvulcanized rubber that is not compounded with short fibers, when a rubber tape in a softened state immediately after being extruded from the extrusion port is pulled in the length direction, the tape extends and becomes thin in both the tape width direction and the thickness direction. . However, in the composite rubber tape in which short fibers are mixed with unvulcanized rubber, the short fibers are oriented in the length direction when extruded from the extrusion port, so the composite rubber tape was pulled with the same force in the length direction and the width direction. In this case, the former elongation is about 1/3 less than the latter elongation.

  Therefore, when a tensile force is applied in the length direction of the composite rubber tape, the tape does not extend in the length direction, but the tape width is narrowed to compensate for the shortage of the composite rubber. Specifically, the composite rubber tape immediately after being extruded from the extrusion port has an arc shape in the width direction. By being pulled in the tape length direction, the tape thickness remains substantially constant and the arc shape gradually increases. Approaching a straight line. That is, the greater the force (drawing speed) for pulling the composite rubber tape, the narrower the width of the composite rubber tape.

  As described above, according to the method for producing a composite tape of the present invention, the tape width can be adjusted without changing the tape thickness, so that the tape width is gradually narrowed in the tape length direction. Tapered tape can be easily produced. Therefore, when forming the outer rubber layer on the cylindrical main body before forming the outer rubber layer, gradually taper from the large diameter side of the cylindrical main body to the small diameter portion with respect to the cylindrical main body whose outer shape is a truncated cone shape. What is necessary is just to wind the composite rubber tape formed so that a width | variety may become helical.

  Thereby, it becomes possible to wind a composite rubber tape without generating wrinkles on the outer periphery of the cylindrical main body. Therefore, a rubber cylinder after vulcanization can be obtained which has short fibers in the outer rubber layer and is excellent in wear resistance and has a smooth surface and little variation in characteristics.

  As a specific method of adjusting the width of the composite rubber tape, the composite rubber tape is pulled out in the length direction by using the drawing means, and the drawing speed of the composite rubber tape drawn by the drawing means is higher than the extrusion speed of the composite rubber tape pushed out from the extrusion device. Set to increase the speed.

  The difference between the drawing speed and the extrusion speed, that is, the greater the force pulling the composite rubber tape, the narrower the tape width approaches the length of the string connecting both ends of the arc-shaped slit, and conversely the drawing speed and the extrusion speed. The smaller the difference (the force pulling the composite rubber tape) is, the wider the tape width approaches the length of the arc.

  As the drawing means, a roll around which the composite rubber tape is wound around the outer peripheral surface is used, and the width of the composite rubber tape can be adjusted by controlling the rotational peripheral speed of the roll as the drawing speed. Thereby, it becomes possible to continuously manufacture and wrap a taper-shaped composite rubber tape whose tape width increases or decreases at a constant interval around the outer peripheral surface of the roll. This facilitates storage of the composite rubber tape. When the composite rubber tape is actually used, it is only necessary to pull out the necessary amount from the roll.

  As described above, the composite rubber tape that has been manufactured once may be stored, but it can also be used as a material for the rubber cylinder simultaneously with the manufacture. That is, in the present invention, while extruding a composite rubber obtained by mixing unvulcanized rubber and short fibers as a composite rubber tape from a slit-like extrusion port formed in an extrusion device, The composite rubber is obtained by spirally winding the composite rubber tape around the outer surface of the mandrel by rotating the mandrel relative to the mandrel while moving it around the surface. A method of manufacturing a rubber cylinder for vulcanizing a layer, wherein the shape of an extrusion port is an arc-shaped slit shape, and the extrusion speed of the composite rubber tape extruded from the extrusion port is higher than the mandrel outer circumferential surface around which the composite rubber tape is wound Set the rotational peripheral speed to be large and move the composite rubber tape winding position from the large diameter part of the mandrel to the small diameter part. Therefore, while such peripheral speed of the mandrel is gradually increased, and so gradually slow down the relative movement speed between the extrusion device and the mandrel.

  As a result, the composite rubber tape manufactured while adjusting the tape width can be directly wound spirally around the mandrel and used as a material for the rubber cylinder. In addition, what is necessary is just to wind a composite rubber tape helically so that the tape back surface may contact | connect the mandrel outer peripheral surface. Further, a composite rubber layer having a more uniform thickness can be formed by winding the composite rubber tape around the mandrel outer peripheral surface while abutting and contacting adjacent tape side surfaces.

  When the composite rubber tape is spirally wound around the outer peripheral surface of the mandrel, the composite rubber tape can be directly wound around the outer peripheral surface of the mandrel to form the composite rubber layer, and the rubber cylinder can be constituted by the composite rubber layer alone.

  In addition, it is also possible to form a cylindrical body before forming the outer rubber layer in advance on the outer peripheral surface of the mandrel and wrap the composite rubber tape around the surface to form a composite rubber layer, which can be used as the outer rubber layer. is there.

  The short fibers used in the present invention preferably have an average fiber diameter of 1 μm to 20 μm and an average fiber length of 3 mm to 20 mm. The composite rubber is preferably mixed with 0.5 to 5 parts by weight of the short fibers with respect to 100 parts by weight of the unvulcanized rubber.

  The average diameter and average length of the short fibers can be obtained by directly observing an appropriate number of arbitrary short fibers under a microscope, measuring the fiber diameter and the fiber length, and calculating the average values. In order to obtain the fiber diameter and fiber length of the short fiber from the rubber cylinder that is the final product, the composite rubber layer of the rubber cylinder is scraped (the composite rubber layer is scraped along the orientation direction of the short fiber. The orientation direction and length of the short fibers can be determined by observing the sample surface with a microscope. Moreover, the diameter of a short fiber can be found by cutting the cut sample in a direction orthogonal to the orientation direction of the short fiber and observing the cut surface.

  The base composition of the unvulcanized rubber used in the present invention is not particularly limited, and any conventionally known composition in this field can be used. For example, in abrasion resistance, water resistance, and processability. Examples thereof include an excellent natural rubber (NR), styrene butadiene rubber (SBR), or a blended composition of NR and cis-1,4-polybutadiene rubber (BR) and / or SBR.

  Examples of the material of the short fibers mixed in these base formulations include carbon fibers, aromatic polyamide fibers, nylon fibers, and polyester fibers that are fiber materials used as reinforcing fibers for tires, belts, and the like. .

  In the present invention, the extrusion port has an arc-shaped slit shape, and the composite rubber tape extruded from the extrusion port is further pulled in the length direction so that the change in the thickness of the composite rubber tape is suppressed and the tape width is changed. Therefore, it becomes possible to obtain a composite rubber tape having a constant thickness and a tapered shape.

[First Embodiment]
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. 1 and 2 are views showing a method for producing a composite rubber tape according to the present invention, FIG. 1 is a schematic view showing an apparatus for producing the composite rubber tape according to the present invention, and FIG. The front view of an extrusion die and sectional drawing of the composite rubber tape extruded from an extrusion die are shown, respectively.

  In the present embodiment, first, as shown in FIG. 1, unvulcanized rubber and short fibers 1 are kneaded by an extrusion device 2, and the obtained mixed rubber 3 is an extrusion die 5 attached to an extrusion head 4. Extruded in a tape form from the extrusion port 6.

  As shown in FIG. 2, the extrusion port 6 is formed in an arcuate slit shape. The short fibers 1 in the composite rubber tape 3 are oriented in the extrusion direction, that is, in the tape length direction A when extruded from the extrusion port 6. As shown in FIG. 1, the composite rubber tape 3 extruded from the extrusion port 6 is taken up by a take-up roll 7 serving as a drawing means.

  The composite rubber tape 3 is originally extruded from the extrusion device at the extrusion speed S1, and in this embodiment, the composite rubber tape 3 is further pulled in the length direction A to adjust the tape width. That is, when the rotational peripheral speed on the outer peripheral surface of the winding roll 7 is S2, the rotational peripheral speed S2 is a speed at which the composite rubber tape 3 is pulled out.

  By setting the rotational peripheral speed S2 to be larger than the extrusion speed S1, the composite rubber tape 3 is smoothly wound around the winding roll 7 in a state where a tensile force (tension) is applied. When the difference between S2 and S1 is small, the tape width of the composite rubber tape 3 approaches the length of the arc of the extrusion port 6 (L1). And the tension | tensile_strength applied to the composite rubber tape 3 becomes large, so that the difference of S2-S1 becomes large, and the tape width of the composite rubber tape 3 approaches the length of the string of the extrusion port 6 (L2).

  Thus, by controlling the rotational peripheral speed S2 of the winding roll 7, the tape width of the composite rubber tape 3 can be adjusted. When the composite rubber tape 3 is wound around the take-up roll 7, when the rotation peripheral speed S2 of the take-up roll 7 is repeatedly increased and decreased at a constant cycle, the tapered composite rubber tape 3 is continuously connected as shown in FIG. Can be obtained. In actual use, each composite rubber tape 3 may be cut.

[Second Embodiment]
FIG. 4 is a schematic view showing a second embodiment of the present invention. The present embodiment is characterized in that a mandrel 8 is used as a take-up means, and the composite rubber tape 3 pushed out from the extrusion port 6 is pulled as it is while being spirally wound.

  As shown in FIG. 4, in the present embodiment, the composite rubber tape 3 extruded from the extrusion port 6 is wound around the mandrel 8. A rotation moving device 9 for rotating the rotation shaft 8 a is connected to the rotation shaft 8 a of the mandrel 8, and the rotation moving device 9 itself can move in the axial direction B of the mandrel 8. Accordingly, the mandrel 8 is movable in the axial direction B while rotating in the axial direction B. In the present embodiment, the mandrel 8 is movable. However, the present invention is not limited to this, and the extrusion device 2 may be movable in the direction opposite to the mandrel axial direction B.

  In the present embodiment, a case where a pumping tube having a truncated cone shape on both the inner surface and the outer surface is manufactured as a rubber cylinder will be described. The pumping tube includes an inner rubber layer 10, an outer rubber layer 12, and a reinforcing layer 11 interposed between the two layers.

  The mandrel 8 is formed in a truncated cone shape, and a cylindrical main body 13 including an unvulcanized inner rubber layer 10 and a reinforcing layer 11 is formed in advance on the outer peripheral surface. In order to form the outer rubber layer 12 with the composite rubber tape 3 on the surface of the cylindrical main body 13, first, the composite rubber tape 3 is set on the large diameter portion 8 b of the mandrel 8. At this time, the composite rubber tape 3 is set in a state where the tape length direction A is inclined with respect to the axial direction B of the mandrel 8 (in the present embodiment, the composite rubber tape 3 is inclined at 55 degrees).

  Next, the rotational movement device 9 moves the mandrel 8 in the axial direction B while rotating it. At this time, the rotational peripheral speed S2 of the mandrel 8 at the winding position of the composite rubber tape 3 is set to be slightly higher than the extrusion speed S1 of the composite rubber tape 3.

  Thereby, the composite rubber tape 3 is smoothly wound spirally around the mandrel 8 with the tape width L1. However, in order to wind the composite rubber tape 3 around the mandrel 8 with a constant inclination angle, the tape width of the composite rubber tape 3 is increased as the winding position of the composite rubber tape 3 moves to the small diameter portion 8c of the mandrel 8. It is necessary to narrow down.

  Therefore, in this embodiment, as the winding position of the composite rubber tape 3 moves to the small diameter portion 8c of the mandrel 8, the rotational peripheral speed S2 of the mandrel is gradually increased and the moving speed of the rotary moving device 9 is gradually increased. To be late. As a result, the tape width of the composite rubber tape 3 approaches L2, and the composite rubber tape 3 can be wound at a constant inclination angle of 55 degrees without any gap while abutting the tape side surfaces adjacent to the surface of the reinforcing layer 11.

  By vulcanizing the unvulcanized pumping tube thus obtained, as shown in FIG. 5, the pumping tube (rubber made of rubber having a smooth surface, little variation in characteristics, and excellent wear resistance is obtained. A cylindrical body 14) can be obtained.

Schematic of an apparatus for carrying out the method for producing a composite rubber tape according to the present invention Front view of the extrusion die of the extrusion apparatus in FIG. Top view showing a state in which composite rubber tapes are continuously connected Schematic showing the second embodiment of the present invention Cross section of rubber cylinder

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Short fiber 2 Extruder 3 Mixed rubber 4 Extrusion head 5 Extrusion die 6 Extrusion port 7 Winding roll 8 Mandrel 8a Rotating shaft 8b Large diameter part 8c Small diameter part 9 Rotation moving device 10 Inner rubber layer 11 Reinforcement layer 12 Outer rubber layer 13 Cylindrical body 14 Rubber cylinder

Claims (6)

A method of producing a composite rubber tape in which short fibers are oriented in the length direction by extruding a composite rubber obtained by mixing unvulcanized rubber and short fibers from a slit-like extrusion port formed in an extrusion device. The extrusion port has an arcuate slit shape, and the composite rubber tape extruded from the extrusion port is further pulled in the length direction, thereby suppressing the change in the thickness of the composite rubber tape and changing the tape width. A method for producing a composite rubber tape characterized by the above. The composite rubber tape is drawn by the drawing means, and the drawing speed of the composite rubber tape drawn by the drawing means is set higher than the extrusion speed of the composite rubber tape pushed out from the extrusion device, and the difference between the drawing speed and the extrusion speed is set. 2. The method of producing a composite rubber tape according to claim 1, wherein the width of the composite rubber tape becomes narrower as the value of becomes larger. 3. The composite according to claim 2, wherein the drawing means is a roll that winds a composite rubber tape around an outer peripheral surface, and the width of the composite rubber tape is adjusted by controlling a rotational peripheral speed of the roll as the drawing speed. Manufacturing method of rubber tape. The short fibers have an average fiber diameter of 1 μm to 20 μm and an average fiber length of 3 mm to 20 mm. The composite rubber is 0.5 parts by weight to 5 parts by weight of the short fibers with respect to 100 parts by weight of unvulcanized rubber. The method for producing a composite rubber tape according to any one of claims 1 to 3, which is a mixture of parts by weight. When the composite rubber obtained by mixing unvulcanized rubber and short fibers is extruded as a composite rubber tape from the slit-shaped extrusion port formed in the extrusion device, and wrapped around the frustoconical mandrel outer peripheral surface Rotating the mandrel while rotating the mandrel relatively moves the mandrel in the axial direction of the mandrel so that the composite rubber tape is spirally wound around the outer surface of the mandrel and the resulting rubber layer is vulcanized A method of manufacturing a cylindrical body, wherein the shape of the extrusion port is an arc-shaped slit shape, and the rotational peripheral speed on the outer peripheral surface of the mandrel around which the composite rubber tape is wound becomes larger than the extrusion speed of the composite rubber tape extruded from the extrusion port. As the winding position of the composite rubber tape moves from the large diameter part of the mandrel to the small diameter part, the mandrel Method for producing a peripheral speed with is to be gradually increased, the rubber tube body, characterized in that the gradually slower relative movement speed between the extrusion device and the mandrel. 6. The method for producing a rubber cylinder according to claim 5, wherein the composite rubber tape is wound around an outer surface of a mandrel while abutting adjacent tape side surfaces.

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