JP2020110940A - Rubber extruding machine and rubber member manufacturing apparatus provided with the same - Google Patents

Abstract

To provide a rubber extruding machine, and a rubber member manufacturing apparatus provided with the same, capable of stably supplying a rubber strip having a constant shape by suppressing pulsation in the extruded rubber strip without causing pulsation in the amount of rubber discharged from a gear pump.SOLUTION: A rubber extruder is provided with a rubber feeding hopper into which a kneaded raw material rubber is fed, a cylindrical cylinder in which the rubber feeding hopper is provided on an upstream side in a rubber extruding direction, and a screw that is provided in the cylinder and pushes toward the downstream side while kneading the raw rubber, a gear pump provided on the downstream side of the cylinder, and an extrusion head for extruding raw material rubber, provided on the downstream side of the gear pump, the rubber extruder comprising a volume control mechanism for changing a volume of the extrusion head according to a rotation of the gear pump.SELECTED DRAWING: Figure 1

Description

The present invention relates to a rubber extruder, particularly a rubber extruder including a gear pump, and a rubber member manufacturing apparatus including the rubber extruder.

A strip wind method is known as a method for forming a rubber member used for a green cover (green tire) of a pneumatic tire. In the strip winding method, a tape-shaped unvulcanized rubber material (rubber strip) continuously extruded from a rubber extruder is continuously wound around a cylindrical molding drum to form an annular rubber member (for example, a tread). Rubber or sidewall rubber).

At this time, as a rubber extruder, there has been proposed a rubber extruder that is combined with a gear pump in the subsequent stage of the screw to quantify the rubber discharge amount (see Patent Document 1).

JP, 2014-73590, A

However, in a rubber extrusion machine combined with a gear pump, the amount of rubber discharged from the gear pump pulsates, and the width of the extruded rubber strip also pulsates (periodically changes), so the strip shape is not constant. There is a defect.

Therefore, the present invention provides a rubber extruder that does not cause pulsation in the amount of rubber discharged from the gear pump, suppresses pulsation in the extruded rubber strip, and can stably supply a rubber strip having a constant shape, and An object is to provide a rubber member manufacturing apparatus including the same.

The present inventor has conducted extensive studies on the solution of the above problems, found that the above problems can be solved by the invention described below, and completed the present invention.

The invention according to claim 1 is
A rubber feeding hopper into which the kneaded raw material rubber is fed, a cylindrical cylinder in which the rubber feeding hopper is provided on the upstream side in the rubber extrusion direction, and a downstream side while kneading the raw material rubber provided in the cylinder. A rubber extruder including a screw that pushes toward, a gear pump that is provided on the downstream side of the cylinder, and an extrusion head that pushes out a raw rubber provided on the downstream side of the gear pump,
The rubber extruder comprises a volume control mechanism for changing the volume of the extrusion head according to the rotation of the gear pump.

The invention according to claim 2 is
The rubber extrusion machine according to claim 1, wherein the volume control mechanism reduces the volume of the extrusion head as the pressure of the rubber flow passage on the outlet side of the gear pump increases.

The invention according to claim 3 is
3. The rubber extruder according to claim 1, wherein the volume control mechanism increases the volume of the extrusion head as the pressure of the rubber flow passage on the outlet side of the gear pump decreases.

The invention according to claim 4 is
The rubber extrusion machine according to claim 2 or 3, wherein the volume control mechanism is configured to change the volume of the extrusion head in a sine wave shape.

The invention according to claim 5 is
Corresponding to the pressure of the rubber passage on the outlet side of the gear pump pulsating in a sinusoidal shape at a constant cycle according to the rotation of the gear pump, the volume control mechanism changes the volume of the extrusion head to the gear pump. 5. The rubber extruder according to claim 4, wherein the pulsation of the pressure of the rubber passage on the outlet side is the same as that of the pressure and the phase is changed by a sine wave having a phase difference of 180°.

The invention according to claim 6 is
A rubber extrusion method for continuously extruding tape-shaped rubber,
For the unvulcanized rubber, using the rubber extruder according to any one of claims 1 to 5, the volume of the extrusion head is reduced as the pressure of the rubber flow passage on the outlet side of the gear pump increases. The rubber extrusion method is characterized in that the pulsation of the rubber discharge amount from the gear pump is suppressed by increasing the volume of the extrusion head as the pressure of the rubber flow passage on the outlet side of the gear pump decreases.

The invention according to claim 7 is
A rubber extruder according to any one of claims 1 to 5,
And a cylindrical molding drum in which tape-shaped unvulcanized rubber materials continuously extruded from a rubber extruder are continuously wound,
In the gear pump, the number of revolutions of the gear pump changes at least once between a low speed and a high speed while continuously winding the unvulcanized rubber material for each member so as to have an appropriate shape, The rubber member manufacturing apparatus is characterized in that the volume control mechanism changes the volume of the rubber passage on the outlet side of the gear pump in accordance with the number of rotations of the gear pump.

The invention according to claim 8 is
A method for manufacturing a cylindrical rubber member in which a tape-shaped unvulcanized rubber material is continuously wound,
It manufactures using the rubber member manufacturing apparatus of Claim 7, It is a manufacturing method of the rubber member characterized by the above-mentioned.

According to the present invention, pulsation is not generated in the amount of rubber discharged from the gear pump, pulsation in the extruded rubber strip is suppressed, and a rubber strip having a constant shape can be stably supplied.

It is sectional drawing which shows one Embodiment of the rubber extrusion machine which concerns on this invention. It is a graph which shows control of the volume (outlet side channel volume) of the rubber channel of a gear pump to the pulsation of the outlet pressure of a gear pump. (A) is a graph which shows the fluctuation of the rubber strip width obtained by the conventional rubber extruder, and (b) is a graph which shows the fluctuation of the rubber strip width obtained by the rubber extruder according to the present invention. It is a graph which shows the fluctuation|variation of a rubber strip width, and the pulsation of the outlet pressure of a gear pump.

1. Basic Concept of the Present Invention FIG. 4 is a graph showing fluctuations in the width of the rubber strip and pulsations in the outlet pressure of the gear pump. In the graph, the set rotation speed of the gear pump is 1.1 rpm. Therefore, the gear pump makes one rotation in about 54 seconds, and during this period, the gear teeth are divided by 11 and meshed 11 times, and the outlet pressure of the gear pump pulsates 11 times. On the other hand, the rubber strip width pulsates four times in 20 seconds, that is, 11 times in approximately 54 seconds. In other words, the rubber strip width pulsates 11 times while the gear teeth mesh with each other 11 times, and the rubber strip width and the outlet pressure of the gear pump pulsate as many times as the gear teeth mesh.

That is, as described above, when the outlet pressure of the gear pump pulsates with the rotation of the gear pump, the same pulsation occurs in the amount of rubber discharged from the gear pump. The pulsation cycle of the outlet pressure of the gear pump and the pulsation cycle of the rubber strip width (T [sec]) are almost the same, and the number of gear teeth (N [sheets]) of the gear pump to be used and the rotation speed (R [R[ rpm]) and the following equation.
T=(60/R)÷N

That is, when the number N of gear teeth and the rotational speed R at the time of extrusion are determined, the pulsation cycle T of the outlet pressure of the gear pump is known, and therefore the present inventor cancels the pulsation (cycle T) of the outlet pressure of the gear pump. As described above, it was found that the above problem can be solved by periodically controlling the volume of the extrusion head, that is, the volume of the rubber flow passage on the outlet side of the gear pump.

2. Configuration of Rubber Extruder Hereinafter, the present invention will be described based on embodiments. FIG. 1 is a sectional view showing an embodiment of a rubber extruder according to the present invention.

As shown in FIG. 1, a rubber extruder 1 according to the present embodiment includes a rubber feeding hopper 10 into which a raw material rubber G1 kneaded in the same manner as the conventional one is fed, a cylindrical cylinder 12, a screw 14, A feature is that not only the gear pump 16 and the extrusion head 18 are provided, but also the volume control mechanism 20 is provided.

The cylinder 12 has a substantially cylindrical shape along the axial direction of the screw 14, and stores the raw material rubber G1 therein. The cylinder 12 is provided with the rubber feeding hopper 10 on the upstream side in the rubber extrusion direction X (hereinafter, may be simply referred to as “upstream side”). Further, the cylinder 12 has a discharge port 13 for discharging the raw rubber G1 pushed by the screw 14 into the gear pump 16 on the downstream side (hereinafter, may be simply referred to as “downstream side”) in the rubber extrusion direction X. have.

The screw 14 is housed in the cylinder 12 and is rotationally driven by a motor (not shown). When the screw 14 is rotationally driven, the raw rubber G1 in the cylinder 12 is kneaded and pushed from the rubber feeding hopper 10 side to the gear pump 16 side (that is, to the downstream side in the rubber extrusion direction X).

The gear pump 16 is provided on the downstream side of the cylinder 12 and is connected to the discharge port 13 of the cylinder 12. The gear pump 16 is a constant volume type extrusion including a casing 30, a chamber 32 in which the raw material rubber G1 formed inside the casing 30 flows, and a pair of extrusion gears 34 arranged in the chamber 32 and meshing with each other. It is a pump.

The chamber 32 includes an inlet 36 located on the upstream side in the rubber extrusion direction X, an outlet 37 located on the downstream side, and a gear housing space 38 located between the inlet 36 and the outlet 37 and housing the extrusion gear 34. , And a rubber flow path 39 located between the gear storage space 38 and the outlet 37.

The inlet 36 of the chamber 32 communicates with the discharge port 13 of the cylinder 12. Therefore, the raw material rubber G1 pushed by the screw 14 is supplied into the chamber 32.

The extrusion gear 34 is rotationally driven by a motor (not shown). As a result, the raw material rubber G1 flowing into the chamber 32 from the inlet 36 is filled in the tooth space of the rotating extrusion gear 34 and is pressure-fed to the outlet 37 side.

In the gear pump 16, when the extrusion gear 34 rotates, the pressure in the rubber flow passage 39 on the outlet side of the gear pump 16 pulsates in a sine wave shape in accordance with the number of times the gear teeth are meshed.

The extrusion head 18 is connected to the outlet 37 of the chamber 32. The extrusion head 18 has an opening 19a and a rubber flow path 19b connected to the opening 19a. The opening 19a has a horizontally long rectangle. Therefore, the raw material rubber G1 fed under pressure from the outlet 37 of the chamber 32 is extruded by the opening 19a of the extrusion head 18 as a tape-shaped unvulcanized rubber material (rubber strip) having substantially the same cross-sectional shape as the opening 19a.

In the case of the present embodiment, the volume control mechanism 20 is provided facing the rubber flow passage 39 of the gear pump 16, and changes the volume of the rubber flow passage 39 in the extrusion head 18 according to the rotation of the gear pump 16.

3. Detailed Configuration of Volume Control Mechanism The volume control mechanism 20 is provided in the rubber passage on the outlet 37 side of the gear pump 16. The “rubber flow passage on the outlet 37 side of the gear pump 16 ”means a rubber flow passage between the downstream side of the extrusion gear 34 of the gear pump 16 and the upstream side of the opening 19 a of the extrusion head 18.

Therefore, the “rubber passage on the outlet 37 side of the gear pump 16” includes the rubber passage 39 of the gear pump 16 and/or the rubber passage 19b of the extrusion head 18. Then, the volume control mechanism 20 changes the volume of the rubber flow passage between the downstream side of the extrusion gear 34 of the gear pump 16 and the upstream side of the opening 19a of the extrusion head 18.

Therefore, in the present embodiment, the volume control mechanism 20 is provided so as to face the rubber passage 39 on the downstream side of the extrusion gear 34 in the casing 30 of the gear pump 16, but depending on the specifications, the volume control mechanism 20 may be provided. May be provided so as to face the rubber flow path 19b of the extrusion head 18. In this case, the volume of the rubber flow passage 19b in the extrusion head 18 is changed according to the rotation of the gear pump 16. Further, it may be provided so as to face a boundary portion between the rubber flow passage 39 of the gear pump 16 and the rubber flow passage 19b of the extrusion head 18 so as to extend over both. In this case, the volume of the rubber flow passage 39 of the gear pump 16 and the volume of the rubber flow passage 19b of the extrusion head 18 change according to the rotation of the gear pump 16.

The volume control mechanism 20 includes a drive device 46 and a control device 48 that controls the drive device 46. The drive device 46 includes, for example, a protruding member 42 that is movable in the thickness direction Y of the raw rubber G1 toward the inside of the rubber flow path 39, and a cylinder 44 that drives the movement of the protruding member 42. The protruding member 42 has a tip portion slightly protruding into the rubber flow path 39. The control device 48 changes the volume of the rubber flow passage 39 in the extrusion head 18 by controlling the position of the protruding member 42 along the thickness direction Y according to the rotation of the extrusion gear 34.

4. Operation of Volume Control Mechanism FIG. 2 shows the volume of the rubber flow channel 39 of the gear pump 16 (outlet side flow volume) with respect to the pulsation of the pressure (outlet pressure) in the rubber flow channel 39 downstream of the extrusion gear 34 of the gear pump 16. It is a graph which shows control of. The solid line shows the pulsation of the outlet pressure of the gear pump 16. The dotted line shows the control of the volume of the rubber flow passage 39 (outlet side flow passage volume) of the gear pump 16 with respect to the solid line.

The pressure in the rubber flow passage 39 on the outlet 37 side of the gear pump 16, that is, the outlet pressure of the gear pump 16 pulsates in a sinusoidal shape according to the number of times the gear teeth of the extrusion gear 34 of the gear pump 16 are meshed.

On the other hand, the volume control mechanism 20 changes the volume of the extrusion head 18 (volume of the rubber passage 39 on the outlet 37 side of the gear pump 16) in a sine wave shape. Specifically, the control device 48 of the volume control mechanism 20 controls the drive device 46 to drive the cylinder 44 in a sine wave shape, whereby the protruding member 42 is directed toward the inside of the rubber flow passage 39 and the raw material rubber G1. It reciprocates in a sinusoidal shape in the thickness direction Y. At this time, the control device 48 causes the reciprocating movement of the protruding member 42 in the sinusoidal shape to be 180° out of phase with the sinusoidal pulsation of the pressure in the rubber passage 39 on the outlet 37 side of the gear pump 16. 42 is reciprocally moved in a sine wave shape to change the volume of the rubber passage 39 on the outlet 37 side of the gear pump 16.

That is, the volume control mechanism 20 reduces the volume of the rubber flow passage 39 of the gear pump 16 as the outlet pressure of the gear pump 16 increases, and decreases the volume of the rubber flow passage 39 of the gear pump 16 as the outlet pressure of the gear pump 16 decreases. increase.

As a result, the volume of the rubber flow path 39 of the gear pump 16 can be periodically controlled so as to cancel the pulsation (cycle T) of the outlet pressure of the gear pump 16, and thus the pulsation of the outlet pressure of the gear pump 16 is suppressed. Therefore, the width variation of the rubber strip G2 extruded from the rubber extruder 1 can be reduced.

Even when the volume control mechanism 20 is provided so as to face the rubber flow passage 19b in the extrusion head 18, the rubber flow passage 19b in the extrusion head 18 is also provided so as to cancel the pulsation of the outlet pressure of the gear pump 16 in the same manner. Since the pulsation of the outlet pressure of the gear pump 16 can be suppressed by periodically controlling the volume, the width variation of the rubber strip G2 extruded from the rubber extruder 1 can be reduced.

5. Configuration of Rubber Member Manufacturing Apparatus A rubber member manufacturing apparatus according to the present invention is, for example, a cylindrical molding drum in which the rubber extruder 1 and a rubber strip G2 continuously extruded from the rubber extruder 1 are continuously wound. (Not shown). The molding drum is arranged on the downstream side of the rubber extruder 1.

The gear pump 16 of the rubber extruder 1 is configured such that the unvulcanized rubber material is continuously wound on each member so as to have an appropriate shape, for example, while the rubber strip G2 is wound once on the molding drum. In addition, the number of revolutions changes between low speed and high speed at least once. Specifically, the rotation speed of the gear pump 16 changes from low speed→high speed→low speed or from high speed→low speed→high speed. Then, the volume control mechanism 20 changes the volume of the rubber passage 39 on the outlet 37 side of the gear pump 16 according to the rotation speed of the gear pump 16.

As a result, the pulsation of the outlet pressure of the gear pump 16 can be suppressed, and the width variation of the rubber strip G2 extruded from the rubber extrusion machine 1 can be reduced, so that the rubber member manufacturing apparatus has an annular rubber member having a small variation in shape. (Eg, tread rubber, sidewall rubber, etc.) can be formed.

1. Example, Comparative Example In the example, the rubber strip G2 was formed by using the rubber extruder 1 having the volume control mechanism 20 shown in FIG. 1 according to the present invention. As shown in FIG. 2, the outlet pressure of the gear pump 16 of the rubber extruder 1 pulsates sinusoidally in the range of 6.0±0.17 [MPa]. The volume of the extrusion head, that is, the volume of the rubber flow path 39 of the gear pump 16 (outlet side flow path volume) is increased or decreased by ±10% from the volume before change by the volume control mechanism 20, and the outlet pressure pulsation cycle T Then, the phase was shifted by 180 degrees to change it into a sine wave.

On the other hand, in the comparative example, a rubber strip was formed using a conventional rubber extruder having no volume control mechanism 20.

2. Evaluation The width variations of the rubber strips formed in each of the examples and comparative examples were compared and evaluated. The evaluation result is shown in FIG. FIG. 3A is a graph showing the variation of the rubber strip width obtained by the conventional rubber extruder (comparative example). FIG. 3B is a graph showing the variation of the rubber strip width obtained by the rubber extruder according to the present invention (Example).

The variation value (maximum value-minimum value) of the width of the rubber strip in the comparative example shown in FIG. 3A was 2.2 mm. On the other hand, the variation value (maximum value-minimum value) of the width of the rubber strip in the example shown in FIG. 3B was 0.7 mm. Therefore, it was confirmed that the pulsation of the strip width can be reduced to about 1/3 or less by the volume control mechanism 20 and the variation in the strip width shape can be reduced.

Although the present invention has been described above based on the embodiment, the present invention is not limited to the above embodiment. Various modifications can be made to the above-described embodiment within the same and equivalent scope as the present invention.

1 Rubber Extruder 10 Rubber Input Hopper 12 Cylinder 13 Discharge Port 14 Screw 16 Gear Pump 18 Extrusion Head 19a Opening 19b Rubber Flow Path 20 Volume Control Mechanism 30 Casing 32 Chamber 34 Extrusion Gear 36 Inlet 37 Outlet 38 Gear Storage Space 39 Rubber Flow Path 42 Protruding member 44 Cylinder 46 Drive device 48 Control device G1 Raw material rubber G2 Rubber strip X Rubber extrusion direction Y Thickness direction

Claims (8)

A rubber feeding hopper into which the kneaded raw material rubber is fed, a cylindrical cylinder in which the rubber feeding hopper is provided on the upstream side in the rubber extrusion direction, and a downstream side while kneading the raw material rubber provided in the cylinder. A rubber extruder including a screw that pushes toward, a gear pump that is provided on the downstream side of the cylinder, and an extrusion head that pushes out a raw rubber provided on the downstream side of the gear pump,
A rubber extrusion machine comprising a volume control mechanism for changing the volume of the extrusion head according to the rotation of the gear pump. The rubber extruder according to claim 1, wherein the volume control mechanism reduces the volume of the extrusion head as the pressure of the rubber flow passage on the outlet side of the gear pump increases. The rubber extrusion machine according to claim 1 or 2, wherein the volume control mechanism increases the volume of the extrusion head as the pressure of the rubber passage on the outlet side of the gear pump decreases. The rubber extruder according to claim 2 or 3, wherein the volume control mechanism is configured to change the volume of the extrusion head in a sinusoidal shape. Corresponding to the pressure of the rubber passage on the outlet side of the gear pump pulsating in a sinusoidal shape at a constant cycle according to the rotation of the gear pump, the volume control mechanism changes the volume of the extrusion head to the gear pump. The rubber extruder according to claim 4, wherein the pulsation of the pressure of the rubber flow passage on the outlet side is the same as that of the pulsation, and the pressure is changed into a sine wave having a phase difference of 180°. A rubber extrusion method for continuously extruding tape-shaped rubber,
For the unvulcanized rubber, using the rubber extruder according to any one of claims 1 to 5, the volume of the extrusion head is reduced as the pressure of the rubber flow passage on the outlet side of the gear pump increases. A rubber extrusion method characterized in that the pulsation of the amount of rubber discharged from the gear pump is suppressed by increasing the volume of the extrusion head as the pressure of the rubber flow passage on the outlet side of the gear pump decreases. A rubber extruder according to any one of claims 1 to 5,
And a cylindrical molding drum in which tape-shaped unvulcanized rubber material continuously extruded from a rubber extruder is continuously wound,
The gear pump is such that the unvulcanized rubber material for each member is continuously wound so as to have an appropriate shape, and the number of revolutions of the gear pump changes at least once between a low speed and a high speed, The rubber member manufacturing apparatus, wherein the volume control mechanism changes the volume of the rubber flow passage on the outlet side of the gear pump according to the number of rotations of the gear pump. A method for manufacturing a cylindrical rubber member in which a tape-shaped unvulcanized rubber material is continuously wound,
A method for manufacturing a rubber member, which is manufactured by using the rubber member manufacturing apparatus according to claim 7.

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