Gear pump for rubber composition and rubber member forming device

Abstract

To provide a gear pump for a rubber composition which can inhibit burn-in of a rubber composition on an inner peripheral surface of a bush ring, and to provide a rubber member formation device including the gear pump for the rubber composition.SOLUTION: A gear pump for a rubber composition includes: a pair of gears which engage with each other to transfer a rubber composition; and bush rings each of which has an inner peripheral surface to fit rotatably with a support shaft of the gear. The inner peripheral surface has: a lubrication groove and an auxiliary groove for allowing the rubber composition to enter a fitting portion between the support shaft and the inner peripheral surface. One end of the lubrication groove opens to the gear side to introduce the rubber composition. Both ends of the auxiliary groove exist on the inner peripheral surface and the auxiliary groove has introduction ports for introducing the rubber composition into the auxiliary groove through the lubrication groove. A rubber member formation device includes the gear pump for a rubber composition.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a gear pump for a rubber composition and a rubber member forming apparatus. [Background technology]

[0002] Generally, pneumatic tires use various band-shaped rubber members with different cross-sectional shapes. The band-shaped rubber members are molded using a rubber member molding device equipped with a gear pump attached to a head having a molding nozzle (see Patent Document 1).

[0003] A gear pump includes a pair of gears housed in a gear pump case and meshing with each other. Each support shaft of the pair of gears is supported by a figure-eight shaped bushing ring having two inner peripheral surfaces into which the support shaft is rotatably fitted. The support shaft rotates in close proximity to the inner peripheral surfaces. As a result, the fitting portion between the support shaft and the inner peripheral surfaces becomes hot.

[0004] To prevent the above-mentioned high temperature condition, a self-lubricating bushing ring is known, in which a lubrication groove extending along the axis of the support shaft and opening to the gear side is provided on the inner peripheral surface of the bushing ring. In a self-lubricating bushing ring, a transported substance such as water or oil transported by a gear pump is supplied to this lubrication groove. The transported substance supplied to the lubrication groove enters the mating portion between the support shaft and the inner peripheral surface and functions as a lubricant. This makes it possible to prevent the mating portion from becoming a high temperature condition.

[0005] Patent Document 2 discloses a bushing ring 1000 having a groove on its inner circumferential surface, as shown in FIG. 11, as a gear pump with a self-lubricating function that enables efficient cooling. FIG. 11 is a schematic plan view of the inner circumferential surface of the bushing ring 1000 described in Patent Document 2. In FIG. 11, the right side of the page represents the gear side, and the left side represents the opposite side of the gear. As shown in FIG. 11, the bushing ring 1000 of Patent Document 2 has a passage (discharge-side lubrication groove) 1100, an auxiliary passage (auxiliary lubrication groove) 1200, and a ring groove 1300 (see claim 1 and FIG. 2 of Patent Document 2). The passage 1100 and the auxiliary passage 1200 each have an opening H6 at their ends on the gear side and a narrow groove opening H9 at their ends opposite the gear. The ring groove 1300 extends semicircularly along the circumferential direction at a position that connects a portion of the passage 1100 with a portion of the auxiliary passage 1200. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-106407 [Patent Document 2] Japanese Patent Application Publication No. 11-50973 Summary of the Invention [Problem to be solved by the invention]

[0007] Like the bushing ring of the conventional gear pump described above, the bushing ring of the gear pump of the rubber member forming apparatus also experiences high temperatures at the mating portion between the support shaft and the inner peripheral surface. The gear pump of the rubber member forming apparatus suffers from the problem that the rubber composition that has entered the mating portion as a lubricant hardens at high temperatures, causing the rubber composition to seize on the inner peripheral surface. In particular, rubber compositions that are prone to seizing due to their high vulcanization rate tend to seize on the inner peripheral surface. This seizure of the rubber composition on the inner peripheral surface increases friction at the mating portion. This increased friction can lead to increased motor driving torque and damage to the machine. Therefore, the gear pump of the rubber member forming apparatus requires frequent disassembly and maintenance. As a result, the gear pump of the rubber member forming apparatus places a greater burden on workers and increases maintenance costs than conventional gear pumps.

[0008] An object of the present invention is to provide a gear pump for a rubber composition that can suppress seizure of the rubber composition on the inner peripheral surface of a bushing ring, and a rubber member forming apparatus equipped with the gear pump for a rubber composition. [Means for solving the problem]

[0009] The present invention provides a gear pump for rubber compositions, which includes a pair of gears that mesh with each other for transporting a rubber composition, and a bushing ring having an inner circumferential surface for rotatably fitting a support shaft of the gear, the inner circumferential surface having a lubrication groove and an auxiliary groove for allowing the rubber composition to enter the fitting portion between the support shaft and the inner circumferential surface, one end of the lubrication groove opening toward the gear for introducing the rubber composition, and both ends of the auxiliary groove existing on the inner circumferential surface and having an inlet for introducing the rubber composition into the auxiliary groove via the lubrication groove, and a rubber part forming device equipped with the gear pump for rubber compositions. [Effects of the Invention]

[0010] The gear pump for a rubber composition of the present invention can suppress seizure of the rubber composition on the inner peripheral surface of the bushing ring. In particular, the gear pump for a rubber composition of the present invention can effectively suppress seizure of the rubber composition in a rubber composition that is prone to seizure. As a result, the gear pump for a rubber composition of the present invention can reduce the frequency of disassembly and maintenance. As a result, the burden on workers and maintenance costs are reduced. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic view of a rubber member forming apparatus according to a first embodiment of the present invention. FIG. [Figure 2] 1 is a schematic view of a gear pump according to a first embodiment of the present invention. [Figure 3] 1 is a schematic view of a bushing ring according to a first embodiment of the present invention. [Figure 4] XX cross-sectional view of the bushing ring shown in FIG. 3. [Figure 5] 1 is a schematic plan view of an inner peripheral surface of a bushing ring according to a first embodiment of the present invention; FIG. [Figure 6] 10 is a schematic plan view of the inner peripheral surface of a bushing ring according to a second embodiment of the present invention; FIG. [Figure 7] 10 is a schematic plan view of an inner peripheral surface of a bushing ring according to a third embodiment of the present invention; [Figure 8] FIG. 2 is a principle diagram showing forces acting on a support shaft in a gear pump for producing a rubber composition. [Figure 9] FIG. 10 is a schematic view of a bushing ring according to a fourth embodiment of the present invention. [Figure 10] FIG. 10 is a schematic plan view of the inner peripheral surface of a bushing ring according to a fourth embodiment of the present invention. [Figure 11] 1 is a schematic plan view of the inner peripheral surface of a bushing ring described in Patent Document 2. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, the present invention will be described in detail based on preferred embodiments, with appropriate reference to the drawings.

[0013] (1) One embodiment of the present invention comprises a pair of meshing gears for transporting a rubber composition; a bushing ring having an inner peripheral surface for rotatably fitting the support shaft of the gear, the inner circumferential surface has a lubrication groove and an auxiliary groove for allowing the rubber composition to enter a fitting portion between the spindle and the inner circumferential surface, one end of the lubrication groove is open to the gear side for introducing the rubber composition; The gear pump for a rubber composition has the auxiliary groove, both ends of which are located on the inner peripheral surface, and which has an inlet for introducing the rubber composition into the auxiliary groove via the lubrication groove.

[0014] The gear pump for a rubber composition of (1) above can suppress seizure of the rubber composition on the inner peripheral surface of the bushing ring.

[0015] (2) In the gear pump for a rubber composition according to (1) above, the lubrication groove extends in the axial direction of the support shaft, and the other end is located on the inner circumferential surface, The lubricating groove further includes a communication groove that connects a portion of the lubrication groove with the introduction port.

[0016] (3) The gear pump for a rubber composition according to (2) above has two or more of the above-mentioned communicating grooves.

[0017] (4) In the gear pump for a rubber composition according to any one of (1) to (3), a position on the inner circumferential surface where a plane having an axis center of one support shaft and an axis center of the other support shaft of the pair of gears as both ends intersects with the inner circumferential surface is set as a reference position, The auxiliary groove is formed at a position on the inner circumferential surface where the central angle is 40° or more and 60° or less in the direction opposite to the rotational direction of the gear, with the axis of the support shaft that fits on the inner circumferential surface as the center and the reference position as 0°.

[0018] (5) In the gear pump for a rubber composition according to any one of (1) to (3), a position on the inner circumferential surface where a plane having an axis center of one support shaft and an axis center of the other support shaft of the pair of gears as both ends intersects with the inner circumferential surface is set as a reference position, The auxiliary groove is formed at a position on the inner circumferential surface where the central angle, centered on the axis of the support shaft that fits on the inner circumferential surface and with the reference position at 0°, is 120° or more and 140° or less in the rotational direction of the gear.

[0019] (6) The gear pump for a rubber composition according to any one of (1) to (5) above has two or more of the auxiliary grooves.

[0020] The gear pumps for a rubber composition according to (2) to (6) can further suppress seizure of the rubber composition on the inner peripheral surface of the bushing ring.

[0021] (7) In the gear pump for a rubber composition according to any one of (1) to (6) above, the bushing rings comprise four bushing rings for respectively fitting the four support shafts of the pair of gears.

[0022] The gear pump for a rubber composition of (7) can be repaired or replaced individually for each of the four bushing rings, which further reduces maintenance costs.

[0023] (8) Another embodiment of the present invention is a rubber member forming apparatus for forming a band-shaped rubber member used in tire manufacturing, comprising: an extruder; a gear pump for a rubber composition according to any one of (1) to (7) above, which is located downstream of the extruder; a head located further downstream of the gear pump for the rubber composition, the extruder has a screw, and is configured such that, by rotating the screw, the rubber composition is kneaded and the rubber composition is supplied to the rubber composition gear pump side, The rubber member forming apparatus is configured such that the head has a die and the rubber composition passes through the die, thereby processing the rubber composition into the band-shaped rubber member.

[0024] The rubber member forming device (8) is equipped with a gear pump for a rubber composition according to any one of (1) to (7) above, and therefore can suppress seizure of the rubber composition on the inner peripheral surface of the bushing ring of the gear pump for a rubber composition.

[0025] FIG. 1 is a schematic diagram of a rubber member forming apparatus 1 according to a first embodiment of the present invention. In FIG. 1, R represents a rubber composition. In FIG. 1, the rubber composition R moves from the left side to the right side of the page. In FIG. 1, the left side is the upstream side of the rubber member forming apparatus 1. The rubber composition R moves through the rubber member forming apparatus 1 from the upstream side to the downstream side, and is discharged from a discharge port H4 provided in a die 220 of a head 200, which will be described later.

[0026] The rubber member forming apparatus 1 includes an extruder 300, a gear pump 100, and a head 200. The gear pump 100 is located downstream of the extruder 300. The head 200 is located downstream of the gear pump 100.

[0027] The extruder 300 includes a cylinder 310 and a screw 320. The cylinder 310 is provided with an inlet 311. The rubber composition R is fed into the extruder 300 from the inlet 311. The screw 320 is rotated by a driving means (not shown). As a result, the rubber composition R is kneaded and transported downstream. In other words, the extruder 300 is configured such that the rubber composition R is kneaded by the rotation of the screw 320 while being transported downstream.

[0028] The gear pump 100 includes a casing 110, a pair of gears 120, and a bushing ring 130 (described later). The casing 110 includes a supply port designated H1 and a discharge port designated H2. Each gear 120 is housed in the casing 110. Each of the pair of gears 120 includes a support shaft 121 and a number of teeth 122. The support shaft 121 is fitted to an inner circumferential surface 135 of the bushing ring 130 (described later) and is supported for free rotation. The teeth 122 are spaced apart and arranged along the periphery of the gear 120. As is clear from FIG. 1 , the gears 120 are configured such that the teeth 122 of one gear 120 mesh with the teeth 122 of the other gear 120.

[0029] The gear pump 100 is equipped with a driving means (not shown). One of the gears 120 is rotated by the driving means. The pair of gears 120 provided in the gear pump 100 are meshed with each other. Therefore, when one of the gears 120 rotates, the other gear 120 rotates. As a result, the rubber composition R that has flowed into the supply port H1 from the extruder 300 is sent to the discharge port H2. The rubber composition R is supplied to the head 200 located downstream of the gear pump 100. In other words, the gear pump 100 is configured to supply the rubber composition R to the head 200 by the rotation of the pair of meshing gears 120.

[0030] The head 200 includes a block-shaped main body 210 and a nozzle 220. The main body 210 constitutes the upstream portion of the head 200. The main body 210 is located downstream of the gear pump 100. The main body 210 is replaceably attached to the gear pump 100. The main body 210 has a hole designated H3 extending from the upstream side to the downstream side. The rubber composition R supplied from the gear pump 100 passes through this hole H3. The nozzle 220 is located downstream of the main body 210. The nozzle 220 is replaceably attached to the main body 210. The nozzle 220 has a discharge port designated H4 extending from the upstream side to the downstream side. The rubber composition R passing through the hole H3 of the main body 210 is discharged from the discharge port H4 of the nozzle 220. When the rubber composition R is discharged from the discharge port H4, the rubber composition R becomes a strip-shaped rubber member. The thickness of the band-shaped rubber member is set within a range of 0.4 mm to 6 mm, and the width of the band-shaped rubber member is set within a range of 4 mm to 40 mm.

[0031] FIG. 2 is a schematic diagram of a gear pump 100 according to a first embodiment of the present invention. The bushing ring 130 is composed of four bushing rings: two bushing rings 130A and two bushing rings 130B. A pair of gears 120 housed in a casing 110 rotates in the direction of arrow A in FIG. 2. One support shaft 121 of the pair of gears 120 is fitted with an inner circumferential surface 135 of the bushing ring 130A, and the other support shaft 121 is fitted with an inner circumferential surface 135 of the bushing ring 130B. In this manner, the bushing ring 130A and the bushing ring 130B are used as a pair. The bushing ring 130 is fitted into a fitting opening designated H5 in the casing 110 so that an opening H6 of a lubrication groove 132 (described later) faces the gears. Furthermore, when the bushing ring 130 is fitted into the fitting opening H5, the surface 131 of the bushing ring 130A and the surface 131 of the bushing ring 130B are configured to be disposed opposite each other.

[0032] As described above, in the bushing ring 130, the bushing rings 130A and 130B are used as a pair. However, the bushing ring 130 can also be an eight-shaped bushing ring in which the bushing rings 130A and 130B are integrated, as in the bushing ring described in the background art. In gear pumps used in rubber member forming apparatuses, the rubber composition may seize onto the inner circumferential surface of the bushing ring, causing damage to the inner circumferential surface. Even if one of the two inner circumferential surfaces of the eight-shaped bushing ring is damaged but the other is not, the entire eight-shaped bushing ring must be repaired or replaced. In contrast, in the gear pump 100, the bushing rings 130A and 130B are configured as separate components. Therefore, damaged bushing rings can be repaired or replaced individually. As a result, maintenance costs are reduced.

[0033] The bushing ring 130 according to the first embodiment of the present invention has, on its inner peripheral surface 135, grooves consisting of a lubrication groove 132, an auxiliary groove 133, and a communication groove 134, which will be described later. When the bushing ring 130 is fitted into the fitting opening H5, the bushing rings 130A and 130B are configured so that, with the opposing surfaces 131 serving as mirror surfaces, they are mirror images of each other, including the grooves described above. Below, the lubrication groove 132, the auxiliary groove 133, and the communication groove 134 will be described based on the bushing ring 130A.

[0034] FIG. 3 is a schematic diagram of a bushing ring 130A according to a first embodiment of the present invention. The bushing ring 130A has a lubrication groove 132, an auxiliary groove 133, and two communicating grooves 134 on an inner circumferential surface 135. The lubrication groove 132 extends along the inner circumferential surface 135 in the axial direction of the support shaft 121. The bushing ring 130A is fitted into the fitting opening H5 so that the opening H6 of the lubrication groove 132 faces the gear 120. This allows the rubber composition R present on the gear 120 side to be introduced into the lubrication groove 132 through the opening H6. The end of the lubrication groove 132 opposite the opening H6 is located on the inner circumferential surface 135. Both ends of the auxiliary groove 133 are located on the inner circumferential surface 135. The auxiliary groove 133 extends along the inner circumferential surface 135 in the axial direction of the support shaft 121, parallel to the lubrication groove 132. The two communicating grooves 134 extend parallel to each other in the circumferential direction of the inner peripheral surface 135. One end of the communicating groove 134 is connected to the lubrication groove 132 by an outlet indicated by H7. The other end of the communicating groove 134 is connected to the auxiliary groove 133 by an inlet indicated by H8. In this manner, the communicating groove 134 is configured to communicate between the lubrication groove 132 and the auxiliary groove 133. As a result, the rubber composition R introduced into the lubrication groove 132 is introduced into the communicating groove 134 from the outlet H7. Then, the rubber composition R introduced into the communicating groove 134 is introduced into the auxiliary groove 133 from the inlet H8.

[0035] Fig. 4 is a cross-sectional view taken along line XX of the bushing ring shown in Fig. 3. The cross-section XX is a cross-section passing through the center of a width W3 (described later) of an auxiliary groove 133 provided on the gear 120 side. Fig. 5 is a schematic plan view of the inner circumferential surface 135 of the bushing ring 130A according to the first embodiment of the present invention. In Fig. 5, the right side of the paper is the gear side (the inside of the casing 110), and the left side is the opposite side of the gear (the outside of the casing 110).

[0036] In comparison with the grooves of the bushing ring 1000 of Patent Document 2 shown in FIG. 11 above, the passage 1100 corresponds to the lubrication groove 132, the auxiliary passage 1200 corresponds to the auxiliary groove 133, and the ring groove 1300 corresponds to the communicating groove 134. Unlike the auxiliary passage 1200, the auxiliary groove 133 has both ends located on the inner circumferential surface 135. The auxiliary passage 1200 has an opening H6 on the gear side. Therefore, a transport substance such as water or oil used for self-lubrication can be supplied from the opening H6 in addition to the ring groove 1200. On the other hand, the auxiliary groove 133 of this embodiment does not have an opening on the gear side. Therefore, the rubber composition R is introduced into the auxiliary groove 133 from the inlet H8 via the communicating groove 134.

[0037] The main components of the rubber composition R are natural rubber and synthetic rubber. The rubber composition R has higher viscosity and hardness than water, oil, and other liquids pumped by typical gear pumps. Therefore, the rubber composition R is less likely to penetrate into the mating portion between the inner circumferential surface of the bushing ring and the gear support shaft than liquids such as water and oil. The auxiliary passage 1200 of Patent Document 2 can supply a material used for self-lubrication through the gear-side opening H6 and the ring groove 1200. When the material is water or oil, it easily penetrates into the mating portion. This enables the gear pump of Patent Document 2 to achieve efficient cooling through its self-lubricating function. On the other hand, when the material is rubber composition R, it is more likely to penetrate into the mating portion. Therefore, in the auxiliary passage 1200, more of the rubber composition R is discharged through the opening H6. As a result, in the bushing ring 1000, the rubber composition R, which is required for self-lubrication, may not sufficiently penetrate into the mating portion. For this reason, it is believed that the gear pump described in Patent Document 2 has a reduced self-lubricating function when the transported material is a rubber composition.

[0038] The auxiliary groove 133 of the bushing ring 130A does not have an opening on the gear side. This prevents the rubber composition R from discharging from the auxiliary groove 133 to the gear side. Therefore, compared to the auxiliary passage 1200, the auxiliary groove 133 allows a greater amount of rubber composition R to enter the mating portion between the inner circumferential surface 135 and the support shaft 121. As a result, when the transported material is rubber composition R, the gear pump 100 is considered to have a better self-lubricating function than the gear pump described in Patent Document 2. Therefore, the gear pump 100 according to the first embodiment of the present invention can effectively prevent the rubber composition from seizing on the inner circumferential surface 135.

[0039] The rubber composition R that has entered the mating portion between the inner circumferential surface 135 and the support shaft 121 as a lubricant is discharged to the opposite side of the gear. In the gear pump 100, the rubber composition R discharged to the opposite side of the gear is discarded as waste. The gear pump described in Patent Document 2 has a mechanism for returning the transferred material to the suction port (supply port H1), forming a return path with the passage 1100, a return groove (not shown), and a return hole. The rubber composition R used as a lubricant may be crushed, burned, or otherwise altered in the mating portion. In the gear pump 100, the rubber composition R that has entered the mating portion does not return to the gear side but is discharged to the opposite side of the gear. Therefore, the altered rubber composition R does not get mixed into the strip-shaped rubber member used in tire manufacturing. As a result, high-quality tires can be manufactured stably using the rubber member forming apparatus 1 of this embodiment.

[0040] 4, D1 indicates the depth of the lubrication groove 132 and the auxiliary groove 133. D3 indicates the diameter of the inner circumferential surface 135. The depth D1 is preferably 1% to 3%, and more preferably 1.5% to 2.5%, of the diameter D3. For example, when D3 is 50 mm, the depth D1 can be 0.50 mm to 1.50 mm.

[0041] 5, W1 indicates the width of the lubrication groove 132 and the auxiliary groove 133. C indicates the circumferential length of the inner circumferential surface 135. The width W1 is preferably 3% to 5% of the length C, and more preferably 3.5% to 4.5%. For example, when the length C is 157 mm, the width W1 can be 4.71 mm to 7.85 mm.

[0042] By configuring the lubrication groove 132 and the auxiliary groove 133 to the depth D1 and width W1 described above, the rubber composition R is smoothly introduced into the lubrication groove 132 and the auxiliary groove 133. In the bushing ring 130 according to the embodiment, the lubrication groove 132 and the auxiliary groove 133 have the same depth D1 and width W1. However, the present invention is not limited to this, and the depth D1 and width W1 of the lubrication groove 132 and the depth D1 and width W1 of the auxiliary groove 133 may be different. From the viewpoint of facilitating the manufacture of the bushing ring 130, it is preferable that the depth D1 and width W1 of the lubrication groove 132 and the auxiliary groove 133 are the same.

[0043] In FIG. 5, L1 indicates the length of the lubrication groove 132. W2 indicates the width of the inner circumferential surface 135. The length L1 is preferably 60% to 90% of the width W2, and particularly 70% to 80%. For example, when the width W2 is 40 mm, the length L1 can be 24 mm to 36 mm. This ensures that the rubber composition R introduced into the lubrication groove 132 can penetrate into the fitting portion between the inner circumferential surface 135 and the support shaft 121. As a result, seizure of the rubber composition on the inner circumferential surface 135 is effectively suppressed.

[0044] 5, L2 indicates the length of the auxiliary groove 133. The length L2 is preferably 50% to 80% of the width W2, and particularly 60% to 70%. For example, when the width W2 is 40 mm, the length L2 can be 20 mm to 32 mm. This ensures that the rubber composition R introduced into the auxiliary groove 133 can penetrate into the fitting portion between the inner circumferential surface 135 and the support shaft 121. As a result, seizure of the rubber composition on the inner circumferential surface 135 is effectively suppressed.

[0045] In FIG. 4, D2 denotes the depth of the communicating groove 134. In FIG. 5, W3 denotes the width of the communicating groove 134. The depth D2 is preferably 30% to 70%, particularly 40% to 60%, of the depth D1 of the auxiliary groove 133. The width W3 is preferably 60% to 90%, particularly 70% to 80%, of the width W1 of the auxiliary groove 133. That is, the depth D2 of the communicating groove 134 is shallower than the depth D1 of the auxiliary groove 133. Furthermore, the width W3 of the communicating groove 134 is narrower than the width W1 of the auxiliary groove 133. This prevents the rubber composition R introduced into the auxiliary groove 133 from returning to the communicating groove 134 from the introduction port H8. This increases the amount of the rubber composition R introduced into the auxiliary groove 133 that penetrates into the fitting portion between the inner circumferential surface 135 and the support shaft 121. As a result, seizure of the rubber composition on the inner circumferential surface 135 is effectively suppressed.

[0046] 4, Y indicates the position of the axis of the support shaft 121 when the support shaft 121 is fitted into the inner circumferential surface 135. Z indicates a reference position where a plane having the axis of one support shaft 121 and the axis of the other support shaft 121 as its two ends intersects with the inner circumferential surface 135 when the bushing ring 130A is fitted into the fitting opening H5. In FIG. 4, the reference position Z is at 0° with position Y as the center. Arrow A shown in FIGS. 4 and 5 indicates the rotation direction of the gear 120.

[0047] The position where the lubrication groove 132 is formed on the inner circumferential surface 135 is not particularly limited. The lubrication groove 132 of the first embodiment is formed on the inner circumferential surface 135 at a position where the center of the width W1 of the lubrication groove 132 is at a central angle of 10° from the reference position Z in the direction of the arrow A, with the position Y as the center. Note that in this embodiment, the lubrication groove 132 is formed on the inner circumferential surface 135 so that the opening H6 is located at a position where the central angle is between 0° and 20° in the direction of the arrow A, for example.

[0048] It is most preferable that auxiliary groove 133 be formed at a position on inner circumferential surface 135 near a load point, as will be described later. However, the position where auxiliary groove 133 is formed is not limited to the position on inner circumferential surface 135 near a load point. For example, auxiliary groove 133 in this embodiment is formed at a position on inner circumferential surface 135 where the center of width W1 of auxiliary groove 133 is centered at position Y and forms a central angle of 50° from reference position Z in the direction opposite to arrow A. It is preferable that auxiliary groove 133 be formed at a position on inner circumferential surface 135 where the central angle in the direction opposite to arrow A is 40° to 60°.

[0049] 6 is a schematic plan view of the inner peripheral surface 135 of a bushing ring 130A according to a second embodiment of the present invention. The bushing ring 130 according to the second embodiment is a modified example in which the lubrication groove 132, the auxiliary groove 133, and the communicating groove 134 of the bushing ring 130 according to the first embodiment are changed. Therefore, the configuration other than the lubrication groove 132, the auxiliary groove 133, and the communicating groove 134 is the same as that of the first embodiment. Below, the lubrication groove 132, the auxiliary groove 133, and the communicating groove 134 will be described based on the bushing ring 130A according to the second embodiment.

[0050] The lubrication groove 132 of the bushing ring 130A according to the first embodiment has an end opposite to the opening H6 on the inner circumferential surface 135. On the other hand, the lubrication groove 132 of the bushing ring 130A according to the second embodiment has a narrow groove opening H9 on the end opposite to the opening H6, as in Patent Document 2. This allows the aged rubber composition R in the lubrication groove 132 to be discharged through the narrow groove opening H9. As described above, the rubber composition R is less likely to penetrate into the mating portion between the inner circumferential surface of the bushing ring and the gear spindle than liquids such as water or oil. Therefore, with the bushing ring 130A according to the second embodiment, there is a risk that more normal rubber composition R capable of functioning as a lubricant will be discharged through the narrow groove opening H9 than the aged rubber composition R. Therefore, from the perspective of efficiently utilizing the rubber composition R as a lubricant, a bushing ring 130A without the narrow groove opening H9 is preferred.

[0051] The auxiliary groove 133 of the bushing ring 130A according to the first embodiment is formed to extend parallel to the lubrication groove 132. On the other hand, the auxiliary groove 133 of the bushing ring 130A according to the second embodiment is formed to extend at an angle relative to the lubrication groove 132. From the viewpoint of facilitating the manufacture of the bushing ring 130, it is preferable that the lubrication groove 132 and the auxiliary groove 133 be formed to extend parallel to each other.

[0052] The bushing ring 130A according to the first embodiment has two communicating grooves 134 extending parallel to one another along the circumferential direction of the inner circumferential surface 135. On the other hand, the bushing ring 130A according to the second embodiment has only one communicating groove 134. The communicating groove 134 of the second embodiment extends at an angle relative to the circumferential direction of the inner circumferential surface 135. From the viewpoint of efficiently introducing the rubber composition R into the auxiliary groove 133, it is preferable that the bushing ring 130A have two or more and four or less communicating grooves 134. From the viewpoint of facilitating the manufacture of the bushing ring 130, it is preferable that the communicating groove 134 be formed so as to extend along the circumferential direction of the inner circumferential surface 135.

[0053] 7 is a schematic plan view of the inner circumferential surface 135 of a bushing ring 130A according to a third embodiment of the present invention. Like the bushing ring 130 according to the second embodiment described above, the bushing ring 130 according to the third embodiment is a modified version of the bushing ring 130 according to the first embodiment, in which the lubrication groove 132, the auxiliary groove 133, and the communicating groove 134 are changed. Below, the lubrication groove 132, the auxiliary groove 133, and the communicating groove 134 will be described based on the bushing ring 130A according to the third embodiment.

[0054] In the bushing ring 130A according to the third embodiment, the lubrication groove 132 is configured to directly communicate with the auxiliary groove 133. More specifically, the end of the lubrication groove 132 opposite the opening H6 is connected to the inlet H8 and communicates with the auxiliary groove 133. Therefore, the rubber composition R introduced into the lubrication groove 132 from the opening H6 is introduced into the auxiliary groove 133 from the inlet H8 without passing through the communicating groove 134. As described above, the communicating groove 134 is shallower and narrower than the auxiliary groove 133. This prevents the rubber composition R from returning from the auxiliary groove 133 to the communicating groove 134. The rubber composition R used as a lubricant needs to be introduced into the lubrication groove 132 from the opening H6. Therefore, the lubrication groove 132 is preferably configured to be deeper and wider than the communicating groove 134. Therefore, the bushing ring 130 according to the third embodiment is configured so that the rubber composition R can easily return from the auxiliary groove 133 to the lubrication groove 132. Therefore, from the viewpoint of preventing seizure of the rubber composition on the inner circumferential surface 135, the bushing ring 130 having the communicating groove 134 is preferred.

[0055] FIG. 8 is a principle diagram illustrating the force acting on the support shaft 121 of the gear pump 100. In the gear pump 100, the pair of gears 120 transport the rubber composition R in the direction of the arrow indicated by B. That is, the rubber composition R that flows into the supply port H1 is sent to the discharge port H2, passes through the hole H3 in the main body 210 of the head 200, and is discharged from the discharge port H4 of the nozzle 220. The opening of the discharge port H4 is narrower than that of the supply port H1. Therefore, within the gear pump 100, the supply port H1 side is a low-pressure region, and the discharge port H4 side is a high-pressure region. As a result, a force indicated by P acts on the support shaft 121 from the discharge port H4 side toward the supply port H1. Furthermore, when the gear 120 rotates, the teeth 122 transport the rubber composition R toward the high-pressure region of the discharge port H2, and a force indicated by Q acts on the support shaft 121, causing the pair of gears 120 to move away from each other. Therefore, a force indicated by R, which is the resultant force of forces P and Q, acts on the support shaft 121. As a result, the fitting portion between the inner circumferential surface 135 and the support shaft 121, where force R is applied, becomes a load point. The vicinity of this load point is likely to be in a high temperature state. Therefore, seizure of the rubber composition R on the inner circumferential surface 135 is likely to occur near the load point.

[0056] Fig. 9 is a schematic diagram of a bushing ring 130A according to a fourth embodiment of the present invention. Fig. 10 is a schematic plan view of an inner peripheral surface 135 of the bushing ring 130A according to the fourth embodiment of the present invention. As with the second and third embodiments described above, the configuration other than the lubrication groove 132, the auxiliary groove 133, and the communication groove 134 is the same as that of the first embodiment.

[0057] The bushing ring 130A according to the fourth embodiment has a configuration in which, in addition to the auxiliary groove 133 of the bushing ring 130A according to the first embodiment, an additional auxiliary groove 133 is provided near the above-mentioned load point. That is, the bushing ring 130A according to the fourth embodiment has two auxiliary grooves 133. Each of the two communicating grooves 134 communicates between the lubrication groove 132 and the two auxiliary grooves 133. As a result, the rubber composition R introduced into the lubrication groove 132 from the opening H6 is introduced into the communicating groove 134 from the outlet H7. Then, the rubber composition R introduced into the communicating groove 134 is introduced into the two auxiliary grooves 133 from the inlet H8.

[0058] Of the two auxiliary grooves 133, one auxiliary groove 133 is formed at the same position as in the first embodiment. The other auxiliary groove 133 is formed at a position where the center of the width of the auxiliary groove 133 is centered at the above-mentioned position Y and forms a central angle of 130° from the reference position Z in the direction of arrow A. Note that in FIG. 10 , the above-mentioned load point is often located at a central angle of 100° to 160°, particularly 120° to 140°, from the reference position Z in the direction of arrow A, centered at the above-mentioned position Y. Therefore, it is particularly preferable that the auxiliary groove 133 be formed at a position where the central angle is 100° to 160°, particularly 120° to 140°, from the reference position Z in the direction of arrow A, centered at the above-mentioned position Y. This effectively suppresses seizure of the rubber composition on the inner circumferential surface 135.

[0059] Table 1 shows the results of determining whether or not the rubber composition R seized on the inner circumferential surface 135 at different outlet pressure peaks after approximately 300 hours of operation of the rubber member forming apparatus 1. The outlet pressure peak is the maximum pressure applied to the die 220, measured by a pressure sensor provided on the head 200. The outlet pressure peak varies depending on the hardness of the rubber composition R, the size of the discharge port H4 of the die 220, and the rotation speed of the gear 120. The harder the rubber composition R is, the smaller the discharge port H4 is, and the faster the rotation speed is, the larger the outlet pressure peak becomes. In the table, the column for the first embodiment shows the results of determining whether or not the rubber composition R seized on the inner circumferential surface 135 when the bushing ring 130 of the first embodiment was used. The column for the fourth embodiment shows the results of determining whether or not the rubber composition R seized on the inner circumferential surface 135 when the bushing ring 130 of the fourth embodiment was used.

[0060] [Table 1]

[0061] As shown in Table 1, in the bushing ring 130 of the first embodiment, seizure of the rubber composition R occurred on the inner circumferential surface 135 under conditions where the outlet pressure peak was 11.4 MPa or higher. On the other hand, in the bushing ring 130 of the fourth embodiment, seizure of the rubber composition R did not occur on the inner circumferential surface 135 even under conditions where the outlet pressure peak was 11.4 MPa or higher. This demonstrates that the bushing ring 130 of the fourth embodiment, which has the auxiliary groove 133 in the vicinity of the above-mentioned load point, can more effectively suppress seizure of the rubber composition R on the inner circumferential surface than the bushing ring 130 of the first embodiment.

[0062] The side reinforcing rubber of a tire must support the weight of the vehicle in the event of a puncture. For this reason, the rubber composition R used for the side reinforcing rubber is often hard. As described above, the harder the rubber composition R, the larger the outlet pressure peak. Therefore, the bushing ring 130 having the auxiliary groove 133 near the above-mentioned load point can be suitably used in the gear pump 100 for transferring the rubber composition R used for the side reinforcing rubber. [Industrial Applicability]

[0063] The above-described technique for suppressing seizure of the rubber composition on the inner peripheral surface of the bushing ring can be applied to various gear pumps for rubber compositions and rubber member forming devices. [Explanation of symbols]

[0064] 1 Rubber component forming device 100 Gear Pump 110 Casing 120 gears 121 Spindle 122 teeth 130 Bush Ring 131 sides 132 Lubrication groove 133 Auxiliary groove 134 Communication groove 135 Inner surface 130A Bush Ring 130B Bush Ring 200 head 210 Main Unit 220 nozzle 300 Extruder 310 cylinder 311 Inlet 320 screw 1000 Bush Ring 1100 Passage (discharge side lubrication groove) 1200 Auxiliary passage (auxiliary lubrication groove) 1300 Ring groove A Arrow indicating the direction of gear rotation B Arrow indicating the direction of transfer of rubber composition R C Circumference of the inner surface D1 Depth of lubrication groove and auxiliary groove D2 Depth of connecting groove D3 Inner diameter H1 supply port H2 outlet H3 hole H4 outlet H5 fitting H6 aperture H7 outlet H8 inlet H9 Hosoguchi L1 Lubrication groove length L2 Auxiliary groove length R Rubber composition W1 Width of lubrication groove and auxiliary groove W2 Inner surface width W3 Width of connecting groove Y-axis center position Z reference position

Claims

1. a pair of intermeshing gears for transporting the rubber composition; a bushing ring having an inner peripheral surface for rotatably fitting the support shaft of the gear; the inner circumferential surface has a lubrication groove and an auxiliary groove for allowing the rubber composition to enter a fitting portion between the support shaft and the inner circumferential surface, one end of the lubrication groove is open to the gear side for introducing the rubber composition; the auxiliary groove has both ends located on the inner circumferential surface and an inlet for introducing the rubber composition into the auxiliary groove via the lubrication groove, A position on the inner circumferential surface where a plane having an axis center of one support shaft of the pair of gears and an axis center of the other support shaft as both ends intersects with the inner circumferential surface is set as a reference position, The auxiliary groove is formed at a position on the inner circumferential surface where a central angle, centered on the axis of the support shaft fitted to the inner circumferential surface and with the reference position being 0°, is 120° or more and 140° or less in the rotation direction of the gear. Gear pump for rubber compounds.

2. the lubrication groove extends in the axial direction of the support shaft, and the other end of the lubrication groove is located on the inner circumferential surface, Further, a communication groove is provided to communicate a part of the lubrication groove with the inlet. A gear pump for use with the rubber composition according to claim 1.

3. The gear pump for a rubber composition according to claim 2 , which has two or more of the communicating grooves.

4. A gear pump for a rubber composition described in any one of claims 1 to 3, having two or more auxiliary grooves.

5. A gear pump for a rubber composition as described in Claim 4, wherein the auxiliary groove is formed at a position on the inner surface where the central angle is greater than or equal to 40° and less than or equal to 60° in the direction opposite to the rotational direction of the gear.

6. 6. The gear pump for a rubber composition according to claim 1, wherein the bushing ring comprises four bushing rings for respectively fitting the four support shafts of the pair of gears.

7. A rubber member forming apparatus for forming a band-shaped rubber member used in tire manufacturing, comprising: an extruder; The gear pump for a rubber composition according to any one of claims 1 to 6, which is located downstream of the extruder; a head located further downstream of the gear pump for the rubber composition, the extruder has a screw, and is configured so that the extruder supplies the rubber composition to the rubber composition gear pump while kneading the rubber composition by rotating the screw, the head has a die, and the head is configured so that the rubber composition passes through the die, thereby processing the rubber composition into the band-shaped rubber member.

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