JP4201770B2 - Urethane coupling - Google Patents

Description

The present invention relates to a urethane cup-ring having a pair of circular hub is bonded via a urethane elastomer having a plurality of projections and the center hole of the end face.

  The elastic shaft joint connects the drive shaft and the driven shaft through an elastic body, and transmits power while absorbing the eccentricity, declination, etc. between the two shafts by deformation of the elastic body. As what uses rubber | gum for the elastic body of such a conventional elastic shaft coupling, there exists what is prescribed | regulated to the rubber shaft coupling of JIS-B1455.

  This rubber shaft joint has a pair of protrusions provided with a plurality of protrusions at equal intervals in the circumferential direction on the end faces of a pair of circular hubs having a center hole fitted into the shaft, and the protrusions are alternately spaced at equal intervals. A rubber elastic body is interposed as a damper in a space formed between the circular shape and the protrusion.

  The transmission of power from the drive shaft to the driven shaft is such that the protrusion on the circular hub on the drive shaft side presses the rubber elastic body, and the rubber elastic body receives the pressing force and presses the protrusion on the circular hub on the driven shaft side. Is done. At this time, even if there is an eccentricity or declination between both shafts, it is absorbed by the elasticity of the rubber elastic body. A urethane coupling using a urethane elastomer is known as a material that sufficiently exerts the function of such a rubber elastic body.

  This urethane elastomer is of a type that thermally cures liquid urethane. The pair of circular hubs are engaged with each other having a space in the projection, and the space is filled with liquid urethane and heated to be cured. Conventionally, this filling operation has been performed by holding a pair of circular hubs in a mold and injecting liquid urethane into the space.

  However, since the conventional urethane casting is performed under atmospheric pressure, there is a problem that bubbles existing in the liquid urethane remain without being removed. If bubbles remain, a predetermined rebound resilience cannot be obtained. The bubbles are generated when the liquid urethane is weighed and stirred, and it is complicated to prevent the bubbles from being generated in the weighing and stirring process.

Therefore, an object of the present invention, while removing bubbles present in the liquid urethane is to provide a urethane cup-ring which can be filled in a space between the pair of circular hub.

In order to achieve the above-mentioned object, the present invention 1 arranges a pair of circular hubs having a plurality of projections on the end face and a center hole so that the projections have a space and are in an engaged state. A urethane elastomer that joins the end surfaces to each other is interposed in the space, and in the urethane elastomer, no bubbles are visually found, and the liquid urethane that fills the space between the pair of circular hubs is a gate portion of a mold. In order to counteract the shrinkage of the urethane in the gate portion, a liquid urethane reservoir portion communicating with the space is provided at least at a position facing the gate portion, so that the periphery of the central hole of the urethane elastomer is provided. It is a urethane coupling that makes the shrinkage of the point symmetric .
According to a second aspect of the present invention, in the first aspect, positioning of the pair of circular hubs with respect to the mold is performed via a shaft, and an end surface of the circular hub is provided at a step portion between a large diameter portion and a small diameter portion of the shaft. , The central hole of one circular hub is formed large, the central hole of the other circular hub is formed small, and the urethane elastomer is interposed so that its inner diameter is the same as that of the large central hole. Is.

  In the present invention, the liquid urethane is reaction-cured while maintaining the centrifugal force. Therefore, the upper and lower molds can be heated to promote the reaction. The liquid urethane from which bubbles have been repelled by the centrifugal force fills the space between the pair of circular hubs, and the reaction hardening proceeds while maintaining that state. Positioning of the pair of circular hubs with respect to the upper and lower molds is performed via a shaft. Liquid urethane filling the space between the pair of circular hubs is injected through the gate portion of the mold. In order to counteract the shrinkage of the urethane in the gate portion, if a reservoir portion of liquid urethane communicating with the space is provided at least at a position facing the gate portion, the shrinkage of the urethane around the shaft becomes point-symmetric. When the shaft is pulled out and made into a urethane coupling, the shrinkage of the urethane around the shaft is a point object around the shaft, so that the eccentricity and declination of the center holes of the pair of hubs are prevented, and a highly accurate urethane cup A ring is obtained.

  In the first and second aspects of the present invention, a gate portion for injecting liquid urethane and a reservoir portion for causing contraction similar to the contraction of urethane in the gate portion are provided around the storage portion, and the reservoir portion is provided. A high-precision urethane coupling can be manufactured by solidifying in a state in which contraction toward the outside occurs at a point-symmetrical portion around the central hole, such as disposing at least a position facing the gate. That is, if the liquid urethane reservoir is disposed at least at a position facing the gate portion around the storage portion, eccentricity and declination of the center holes of the pair of circular hubs can be prevented.

  In the present invention 3-4, liquid urethane is injected into the space between a pair of circular hubs by centrifugal force, and the liquid urethane is reacted and cured while maintaining centrifugal force. Therefore, the liquid urethane is generated in the liquid urethane during weighing or stirring. The removed air bubbles are removed, and a pair of circular hubs can be joined via a predetermined urethane elastomer.

  In the present invention 5 to 10, since the pair of circular hubs are positioned using the shaft, the positional relationship between the projections of the circular hub and the concentricity of the circular hub can be maintained with high accuracy. Since it only needs to be attached to the mold, the work process can be streamlined. In addition, the axial position of the pair of circular hubs is determined by the axial stepped portion of the shaft, and the circumferential position of the pair of circular hubs is determined by screwing to the shaft. Is easy to do. Further, the shaft and the mounting body of the circular hub can be easily set in the upper and lower molds while maintaining the shaft reference accuracy of the pair of circular hubs by the upper and lower projecting portions of the shaft.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of a manufacturing apparatus used for manufacturing the product of the present invention, FIG. 2 is a top view of a lower mold in the manufacturing apparatus, and FIG. 3 is a mounting state of a shaft and a hub in the manufacturing apparatus. FIG. 4 is a vertical cross-sectional view showing a mounting state of the shaft and the hub.

  First, the whole manufacturing apparatus of the present invention will be described with reference to FIGS. The manufacturing apparatus includes a shaft 11 that fixes a pair of circular hubs 2 and 3 at predetermined positions, a lower mold 12 and an upper mold 13 that can fix many of the shafts 11, and a rotating plate that supports the lower mold 12. (Drive means) 14 and a drive motor (drive means) 15 for rotating the rotating plate 14 at high speed.

  The drive motor 15 has a vertically upward output shaft 15a attached to the center of rotation of the horizontally disposed rotating plate 14 by fitting or the like. A circular lower mold 12 is fixed on the rotating plate 14 using bolts 16 so that the centers thereof coincide with each other.

  The circular lower mold 12 includes a lower two-stage hole portion 19 including a lower fixing portion 17 corresponding to the lower protruding portion 41 of the shaft 11 and a lower storage portion 18 corresponding to one of the circular hubs 2 and 3. As shown in FIG. 2, they are equally arranged (12 equal parts in the illustrated example) on the concentric circle 21 of the rotation center 20. A lower circular storage portion 22 is provided around the rotation center 20, and lower gate portions 23 that extend radially from the lower circular storage portion 22 to the respective lower storage portions 18 are disposed.

  Returning to FIG. 1, the circular upper mold 13 is also an upper two-stage hole including an upper fixing portion 24 corresponding to the upper protruding portion 42 of the shaft 11 and an upper storage portion 25 corresponding to the other of the circular hubs 2 and 3. The portion 26 is disposed so that the axial center of the lower two-stage hole portion 19 of the lower mold 12 coincides. Further, an upper circular storage portion 27 and an upper gate portion 28 that coincide with the lower circular storage portion 22 and the lower gate portion 23 of the lower mold 12 are also disposed in the upper mold 13. Note that the upper and lower circular storage portions 22 and 27 and the upper and lower gate portions 23 and 28 can be provided on only one of the upper and lower molds 12 and 13 as an integral circular storage portion and gate portion.

  An injection port 29 is provided along the rotation center 20 of the upper mold 13 to reach the upper and lower circular storage portions 22 and 27. The upper and lower molds 12, 13 are fixed in a closed state with bolts 13a. The upper and lower molds 12 and 13 can be opened and closed by the bolt 13a. The upper and lower molds 12 and 13 incorporate heating means such as an electric heater (not shown). Further, an O-ring (elastic ring) 30 that seals between the outer periphery of the circular hub near the mating surfaces of the second storage portion 18 of the lower mold 12 and the second storage portion 25 of the upper mold 13, 31 is disposed.

  When the gate parts 23 and 28 of the upper and lower molds are started from the shaft 11, the first reservoir parts 32U and 32L, which are separated by the upper and lower molds, are arranged at + 180 ° parallel to each other and + 90 °. The second reservoirs 33U and 33L, which are separated by the upper and lower molds, are arranged at positions that are perpendicular to each other, and the third reservoir 34U that is located by being separated by the upper and lower molds at an orthogonal position that is separated by -90 °. , 34L are disposed. The gate portions 23, 28, the first reservoir portions 32U, 32L, the second reservoir portions 33U, 33L, and the third reservoir portions 34U, 34L are a pair of circular hubs 2, 3 of the upper and lower mold storage portions 18, 25. It is provided so that it may communicate with the space between.

  The first reservoir portions 32U and 32L have the same length and the same width as the gate portions 23 and 28. If the gate portions 23 and 28 are present, the amount of urethane increases and the amount of shrinkage increases accordingly. The shrinkage of the urethane in the first reservoir portions 32U and 32L can directly counter the shrinkage of the urethane in the gate portions 23 and 28. When there is no first reservoir portion 32U, 32L, the shaft 11 resists this contraction. Therefore, when the shaft 11 is pulled out, the shrinkage of the urethane on the side where the gate portions 23 and 28 are present increases, and the eccentricity / deflection angle of the pair of circular hubs occurs. Therefore, in order to counteract the shrinkage of the urethane of the gate portions 23 and 28, the first reservoir portions 32U and 32L are provided at least at an opposing position away from the gate portions 23 and 28 by + 180 °. When the same phenomenon as the urethane shrinkage in the gate portions 23 and 28 is caused to be pointed around the shaft 11, the shrinkage around the shaft 11 becomes substantially uniform. Therefore, it is preferable that the second reservoir portions 33U and 33L and the third reservoir portions 34U and 34L have the same length and the same width as the gate portions 23 and 28. As shown in the figure, gate portions 23, 28, first reservoir portions 32U, 32L, second reservoir portions 33U, 33L, and third reservoir portions 34U, 34L are provided at positions equally divided around the storage portions 18, 25. Then, the shrinkage of urethane in the spaces inside the storage portions 18 and 25 is balanced with respect to the shaft 11 by the point object. As a result, when the shaft 11 is extracted to form a uretan coupling, the eccentricity and declination of the center holes of the pair of circular hubs caused by the uneven distribution of urethane shrinkage are suppressed.

  The attachment body of the circular hubs 2 and 3 and the shaft 11 will be described with reference to FIGS. 4 is a cross-sectional view taken along line XX of FIG. In FIG. 3, a first shaft portion 43 and a second shaft portion 44 that are sequentially reduced in diameter are provided from the large-diameter first projecting portion 41 to the small-diameter second projecting portion 42. A first step portion 45 is formed between the large-diameter first projecting portion 41 and the small-diameter first shaft portion 43, and the first step portion 45 is formed between the large-diameter first shaft portion 43 and the small-diameter second shaft portion 44. A two-stage portion 46 is formed. Further, an O for sealing between the center holes of the circular hubs 2 and 3 near the end surface of the first shaft portion 43 facing the circular hub 2 and near the end surface of the second shaft portion 44 facing the circular hub 3 is provided. Rings (elastic body rings) 47 and 48 are provided. Furthermore, plane portions 49 and 50 facing the bolt holes of the circular hubs 2 and 3 are provided at an intermediate position of the circular hub 2 of the first shaft portion 43 and an intermediate position of the circular hub 3 of the second shaft portion 44. Yes.

  The structure of the circular hubs 2 and 3 will be described with reference to FIGS. 6 is a cross-sectional view taken along line YY of FIG. In FIG. 5, a pair of circular hubs 2 and 3 made of aluminum alloy have center holes 4 and 5, respectively, and protrusions 6 and 7 project from end faces facing each other. As shown in FIG. 6, the three protrusions 6, 6, 6 of the circular hub 2 and the three protrusions 7, 7, 7 of the circular hub 3 are arranged in mesh with each other through a space separated by the same distance. Yes. The urethane elastomer 8 in this space is structured to join a pair of circular hubs 2 and 3. Usually, the center hole 4 of one circular hub 2 has a larger diameter than the center hole 5 of the other circular hub 3. The urethane elastomer 8 is a ring having an inner diameter that is the same as that of the center hole 4, and a portion extending radially from the ring fills a space between the protrusions 6 and 7. Further, a bolt hole 9 that opens to the center hole 4 is provided at an intermediate position of the main body of the circular hub 2, and a bolt hole 10 that opens to the center hole 5 is also provided at an intermediate position of the main body of the circular hub 3. In the case where an aluminum alloy is used for the circular hubs 2 and 3, in order to improve the adhesiveness with the urethane elastomer 8, the adhesive is previously applied to the opposing portions of the circular hubs 2 and 3. It is desirable to perform a treatment for improving the performance.

  Returning to FIG. 3, the first shaft portion 43 of the shaft 11 has an outer diameter that fits into the center hole 4 of the circular hub 2, and the end portion on the opposite surface side of the circular hub 2 hits the first step portion 45. An axial position with respect to the shaft 11 is determined. Further, the second shaft portion 44 of the shaft 11 has an outer diameter that fits into the center hole 5 of the circular hub 3, and the end portion on the opposite surface side of the circular hub 3 abuts on the second step portion 46, so that the shaft 11 is connected to the shaft 11. The direction position is determined. Thus, the distance ε between the protrusion 6 of the circular hub 2 and the circular hub 3 and the distance ε between the protrusion 7 of the circular hub 3 and the circular hub 2 are automatically determined.

  When the set screw 51 is screwed into the bolt hole 9 of the circular hub 2, the tip of the set screw 51 hits the plane portion 49 perpendicularly, and the circumferential position of the shaft 11 of the circular hub 2 is determined. Similarly, when the set screw 52 is screwed into the bolt hole 10 of the circular hub 3, the tip of the set screw 52 hits the plane part 50 perpendicularly, and the circumferential position of the shaft 11 of the circular hub 3 is determined. As a result, as shown in FIG. 4, the gap 53 between the protrusion 6 of the circular hub 2 and the protrusion 7 of the circular hub 3 becomes equal in angle α, and the circumferential position of the circular hubs 2 and 3 is automatically set. It has come to be decided.

  As described above, the axial positions and the circumferential positions of the circular hubs 2 and 3 with respect to the shaft 11 can be obtained by simply fitting the circular hubs 2 and 3 to the shaft 11 and placing the circular hubs 2 and 3 against the step portions 45 and 46 and screwing the set screws 51 and 52. It is decided. A predetermined space 54 is formed between the circular hubs 2 and 3 with the protrusions 6 and 7 interposed therebetween.

  Examples of the polyurethane elastomer include diisocyanates represented by toluene disissocyanate (TDI), methylene diisocyanate (MDI), and paraphenylene diisocyanate (PPDI), polyester polyols, polyether polyols, and polycarbonate polyols. A polyurethane elastomer obtained by blending a curing agent (crosslinking agent) with a prepolymer composed of two or more species is used.

  Examples of the polyester-based polyol include a condensate of a polycarboxylic acid and a low molecular polyol and a molecular weight of 500 to 10,000. Examples of the polyether-based diol include those obtained by ring-opening addition polymerization using an alkylene oxide (for example, ethylene oxide or propylene oxide) as an initiator and a polyhydric alcohol (for example, diethylene glycol) as an active hydrogen compound. It is done. Examples of the polycarbonate-based polyol include those obtained by condensation of a conventionally known polyol (polyhydric alcohol) with phosgene, chloroformate ester, dialkyl carbonate or diallyl carbonate, and those having various molecular weights.

  The method for producing a urethane prepolymer (liquid urethane) by reacting one or more of the polyols with a diisocyanate represented by TDI, MDI, PPDI and the like is not particularly limited. It can be carried out by a known method including temperature, reaction time, presence or absence of a solvent and the like. In order to obtain the urethane elastomer used in the present invention, the urethane prepolymer obtained as described above and a curing agent may be mixed to cure (reaction cure) the urethane prepolymer.

  The curing agent that can be used is not particularly limited, and any conventionally used curing agent may be used when a urethane prepolymer is cured to produce a urethane elastomer. For example, a polyol compound, a polyamine compound, etc. are mentioned. The polyol compound is not particularly limited, and any of primary polyol, secondary polyol, and tertiary polyol may be used.

  The method for mixing the above curing agent and the urethane prepolymer obtained as described above and curing (crosslinking) the urethane prepolymer is not particularly limited. For example, for the urethane prepolymer It can be carried out by ordinary methods including the mixing ratio of the curing agent, curing temperature, curing time and the like. The polyurethane elastomer used in the present invention may contain additives and the like. These additives are plasticizers, flame retardants, fillers, stabilizers, colorants, and the like. Stabilizers are conventionally used antioxidants, ultraviolet absorbers, light stabilizers, hydrolysis inhibitors, and the like.

  Below, the manufacturing method of this invention goods using the manufacturing apparatus mentioned above is demonstrated. As shown in FIG. 3, the circular hub 2 having the large center hole 4 is first inserted into the shaft 11, and the end surface of the circular hub 2 is brought into contact with the first step portion 45. Next, the circular hub 3 having the small center hole 5 is fitted into the shaft 11, and the end surface of the circular hub 3 is brought into contact with the second step portion 46. Then, the set bolt 51 is screwed into the screw hole 9 of the circular hub 2, and the tip of the set bolt 51 is applied to the flat portion 49. Similarly, the set bolt 52 is screwed into the screw hole 10 of the circular hub 3, and the tip of the set bolt 52 is applied to the flat portion 50. In this way, the axial position and the circumferential position with respect to the shaft 11 of the pair of circular hubs 2 and 3 are determined, and the space 54 such as the clearance 53 between the axial clearance ε and the protrusions 6 and 7 is of a predetermined shape ( First step).

  The bolt 13a of FIG. 1 is removed, and the upper mold 13 is removed. The attachment body of the shaft 11 and the circular hubs 2 and 3 in FIG. 3 is set at a predetermined position of the lower mold 12 by fitting the lower protruding portion 41 into the lower fixing portion 17. Next, the upper mold 13 is lowered along the rotation center 20, and the upper projecting portion 42 is fitted into the upper fixing portion 24 to ensure concentricity with the lower mold 12 of the upper mold 13, and the bolt 13 a is screwed in. . Then, twelve of the attachment body of the shaft 11 and the circular hubs 2 and 3 in FIG. 3 are set in the upper and lower molds 12 and 13, and the space between the circular hubs 2 and 3 is the gate portions 23 and 28 and the circular storage. The inlet 27 is in communication with the parts 27 and 28. When the drive motor 15 is rotated in this state, the upper and lower molds 12 and 13 are rotated via the rotating disk 14, and a large centrifugal force is generated on the attachment body of the shaft 11 and the circular hubs 2 and 3. When liquid urethane is injected from the injection port 29 while the centrifugal force is generated, the liquid urethane fills the space between the circular hubs 2 and 3 via the circular storage portions 27 and 28 and the gate portions 22 and 27 ( Second step).

  When the upper and lower molds 12 and 13 are heated while the centrifugal force is generated, the reaction hardening of the liquid urethane proceeds. Since the centrifugal force remains generated, even if bubbles are present in the liquid urethane, the bubble portions having a low specific gravity gather in the circular reservoirs 27 and 28, and the liquid urethane in the space between the circular hubs 2 and 3 is the most centrifugal. Since the force is large, there are almost no bubbles. When the liquid urethane in the space of the circular hubs 2 and 3 is reactively cured and changed into a urethane elastomer, the circular hubs 2 and 3 are joined with the urethane elastomer (third step). At this time, the urethane in the space of the circular hubs 2 and 3 is pulled by the shrinkage of the urethane in the gate portions 23 and 28, but the pull from the first reservoir portions 32U and 32L counteracts, and the second reservoir portions 33U and 33L. The third reservoirs 34U and 34L restrict the movement of the urethane in the space of the circular hubs 2 and 3, and the shrinkage of the urethane is made uniform in the circumferential direction. Therefore, when the shaft 11 is pulled out, the eccentricity and declination of the center holes of the pair of circular hubs due to the contraction of the urethane do not occur.

  The upper and lower molds 12, 13 are stopped from rotating, the bolts 13a are removed, and the upper mold 13 and the lower mold 12 are opened. Then, twelve of the attachment bodies of the shaft 11 and the circular hubs 2 and 3 are removed from the lower mold 12. Then, the set screws 51 and 52 are loosened and removed, and the shaft 11 is removed from the mounting body. A urethane elastomer gate portion clogged in the space between the circular hubs 2 and 3 is cut to obtain a urethane coupling having a predetermined shape (fourth step).

  In the second and third steps of applying centrifugal force, excessive leakage of the liquid urethane into the storage portion 25 is stopped by the elastic rings 30 and 31, and the liquid urethane is also excessively inserted into the center holes 4 and 5. Leakage is stopped by elastic rings 47 and 48 in FIG. Therefore, the finishing operation until a urethane coupling having a predetermined shape is obtained is simplified. However, the elastic rings 47 and 48 are not necessarily required. This is because it may be preferable to omit the elastic rings 47 and 48 in order to increase the accuracy of shaft runout.

  As described above, 12 urethane couplings can be obtained in a single centrifugal force application step. Further, since the pair of circular hubs 2 and 3 are positioned by the shaft 11, even if a large centrifugal force is applied, the positional relationship between the pair of circular hubs 2 and 3 does not shift, and a high-precision urethane cup A ring is obtained.

A concentric circle diameter (PCB) of 205 mm was used, and an upper and lower mold capable of setting 12 attachment bodies of a shaft and a circular hub was used. As a prepolymer (liquid urethane), polyester-based T.P. D. I. Table 1 shows A-931 (Uniroy), a polyol-based crosslinker, and MOCA (Wakayama Seika), an amine-based crosslinker, as a crosslinking agent for Vibrathane 8050 (Uniroy), a urethane prepolymer. The mixture was mixed as shown in FIG.

  The horizontally disposed upper and lower molds are rotated at 4000 rpm ± 500 rpm around the central axis, and the centrifugal force is applied for a predetermined time of 30 to 40 minutes. At the same time, the upper and lower molds are heated at 90 to 130 ° C. Cured. After curing, the shaft was removed from the upper and lower molds, and the circular hub joined with the urethane elastomer was removed from the shaft to obtain a urethane coupling. At this time, no bubbles were visually observed in the urethane elastomer after crosslinking, and the rebound resilience of the urethane elastomer was uniform at 30% (JIS K 6301). The centrifugal force at 3500 rpm is 1404G, and the centrifugal force at 4500 rpm is 2321G. Therefore, the centrifugal force required at the time of urethane injection is 1350-2400G.

  Next, it was measured how much the eccentricity and declination of the center holes of the pair of circular hubs can be prevented when the reservoir portion is disposed at a position that can resist the urethane shrinkage of the gate portion of the upper and lower molds.

  As shown in FIG. 2, both a mold in which the gate part and the three reservoir parts are equally arranged on the circumference and a mold in which only the gate part is arranged without the reservoir part are used, and the hub diameter is 30 mm, 96 urethane couplings with shaft diameters of 8 mm at both ends were obtained with three reservoirs and 59 without reservoirs. The shaft of one hub was fitted into the rotating shaft, and the runout of 1 mm inside the shaft of the other hub was measured with a test indicator. The results are shown in Table 2. In Table 2, the average value is an average of 96 or 59 measurement values, MAX is the maximum of 96 or 59 measurement values, and MIN is 96 or 59 measurement values. The smallest of It can be seen that if the shrinkage of urethane in the mold is made uniform in the circumferential direction, the eccentricity and declination of the resulting urethane coupling will be greatly improved.

It is sectional drawing of the manufacturing apparatus used for the manufacturing method of this invention product. It is a top view of the lower metal mold | die in the said manufacturing apparatus. It is a cross-sectional view which shows the attachment state of the shaft and hub in the said manufacturing apparatus. It is a longitudinal cross-sectional view which shows the attachment state of the said shaft and a hub. It is a cross-sectional view of the urethane coupling by the said manufacturing method. It is a longitudinal cross-sectional view of the urethane coupling by the said manufacturing method.

Explanation of symbols

2 Circular hub 3 Circular hub 4 Center hole 5 Center hole 6 Projection 7 Projection 8 Urethane elastomer 9 Screw hole 10 Screw hole 11 Shaft 12 Lower mold 13 Upper mold 14 Rotating plate 15 Drive motor (drive means)
17 Lower fixing part 18 Lower storage part 20 Center of rotation 23, 28 Gate part 24 Upper fixing part 25 Upper storage part 29 Inlet 30 Elastic ring 31 Elastic ring 32U, 32L First reservoir part 33U, 33L Second reservoir part 34U, 34L Third reservoir portion 41 Lower protrusion portion 42 Upper protrusion portion 43 First shaft portion 44 Second shaft portion 45 First step portion 46 Second step portion

Claims (2)

A pair of circular hubs having a plurality of projections on the end surface and a center hole are arranged so that the projections have a space and are in an engaged state, and a urethane elastomer that joins the end surfaces is interposed in the space. ,
In the urethane elastomer, no bubbles are found visually,
Liquid urethane that fills the space between the pair of circular hubs is injected through a gate portion of a mold, and at least a reservoir portion of liquid urethane that communicates with the space in order to counteract urethane shrinkage in the gate portion. by providing a position facing the gate portion, the central hole urethane coupling shrinkage is set to be in point symmetry around the urethane elastomer. Positioning of the pair of circular hubs with respect to the mold is performed via a shaft, and the end surface of the circular hub is brought into contact with a step portion between the large-diameter portion and the small-diameter portion of the shaft. The urethane coupling according to claim 1, wherein the hub has a large center hole, the other circular hub has a small center hole, and the urethane elastomer is interposed so as to have the same inner diameter as the large center hole.

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