JP5051846B2 - Mold - Google Patents

Description

  The present invention relates to a molding die, and more particularly, to a molding die having a simple structure capable of forming a flat and highly accurate elastic layer with high reproducibility.

  The roller 50 provided with the elastic layer 52 on the outer peripheral surface of the shaft body 51 as shown in FIG. 7 is widely used in various fields. For example, printers such as laser printers and video printers, copiers, facsimiles, and complex machines of these types have various images provided with various rollers such as developing rollers, fixing rollers, and conveying rollers according to their functions. A forming apparatus, for example, an image forming apparatus using an electrophotographic method is employed.

  Such a roller 50 is normally manufactured by forming the elastic layer 52 on the outer peripheral surface of the shaft 51 using a molding die. As a molding die used for molding the elastic layer 52, for example, as shown in FIG. 9, a tubular die 101 and a sprue that is attached to one end of the tubular die 101 and formed so as to penetrate therethrough. Examples thereof include a molding die 100 including one end mold 103 having 104 and another end mold 102 attached to the other end of the tubular mold 101 and having a vent 105 formed therethrough. As another example of the molding die, for example, the die disclosed in Patent Document 1 is composed of “an upper piece 1, a die body 2 and a lower piece 3. The lower piece 3 has an injection gate. There is a hole 3a, the upper piece 1 is provided with a gate hole 1a, the lower piece 3 is provided with a liquid reservoir 3b, and the upper piece is provided with an overflow receiver 1b "(see FIG. 1 and column 0022). reference.).

  For example, as shown in FIG. 10, these molding dies are generally tubular dies via two end mold jigs 106 so that the molding dies 100 are not decomposed due to thermal expansion of the molding material. In the state pressed in the axial direction (usually vertical direction) 101, it is subjected to the molding process. At this time, as shown in FIG. 10, if the sprue 104 (the gate hole 3 a for injection) and the vent 105 (the gate hole 1 a) are closed by the end mold jig 106, The injected molding material may thermally expand, and the internal pressure may vary greatly, which may reduce the deflection accuracy of the molded elastic layer.

  By the way, when a molding material is injected into these molding dies from the sprue 104 (gate hole 3a for injection), the gas contained in the molding material and / or the molding material is injected into the injected molding material. In some cases, gas that is considered to be entrained may appear. If the gas that has appeared is not removed before the molding material is cured, the molding material is cured while containing these gases, and bubbles derived from these gases are generated and / or elasticity around the bubbles. The layer may sink and the flatness of the formed elastic layer may be impaired.

  In particular, as described above, when the sprue 104 (the gate hole 3a for injection) and the vent 105 (the gate hole 1a) are closed by the end mold jig 106, the flatness of the elastic layer is impaired. Needless to say, the gas appearing in the molding material may cause the internal pressure of the molding material to vary more greatly, and the deflection accuracy of the elastic layer may be greatly reduced.

  Further, when the molding material is cured, the molding material is also present in the sprue 104 (gate hole 3a for injection), the vent 105 (gate hole 1a), and the overflow receiver 1b. Naturally, it hardens in the sprue 104 (gate hole 3a for injection), the vent 105 (gate hole 1a), and the overflow receiver 1b. Since the sprue 104 (the gate hole 3a for injection) and the vent 105 (the gate hole 1a) are drilled so as to have a small diameter as long as the molding material can be injected and discharged, the elastic layer after molding is formed. When the mold is removed from the molding die, a cured body or a part thereof cured in the sprue 104 (the gate hole 3a for injection) and the vent 105 (the gate hole 1a) may be left in the interior. Further, the cured body or a part thereof may be left inside the overflow receiver 1b, particularly near the bottom. Then, it is not easy to remove the cured body or a part thereof left in such a portion. If the cured body or a part thereof is left, the sprue 104 (the gate hole 3a for injection) and / or Alternatively, the vent 105 (gate hole 1a) or the like may be substantially blocked. When manufacturing a plurality of rollers, particularly when the vent 105 (gate hole 1a) is in a closed state, the molding material is heat-cured in a state of being substantially sealed in the molding die. Then, as described above, there may be a case where an elastic layer having a flat and uniform runout accuracy cannot be formed with good reproducibility.

JP 2003-191244 A

  An object of the present invention is to provide a molding die having a simple structure capable of forming a flat elastic layer with high runout accuracy with high reproducibility.

As means for solving the problems,
The first aspect of the present invention includes a tubular mold in which a shaft body is inserted, a first end mold having a sprue that closes one opening of the tubular mold and is formed to penetrate in the axial direction; A second end mold for closing the other opening in the tubular mold, and an end mold jig to be mounted on the second end mold at the time of heat molding,
The second end mold includes an end mold body having a holding hole for holding the shaft body, and a circumference smaller than a depth of the holding hole from one end of the end mold body. Projecting in the direction, and having a flange portion formed with a vent penetrating in the thickness direction,
The end mold jig has a recess communicating with the outer opening of the vent and an exhaust part extending in the axial direction from the recess.

  The molding die according to the present invention includes a second end die having a small flange portion and an end die jig having a recess and an exhaust portion. As a result, in the molding die according to the present invention, even if a gas appears in the molding material injected into the molding die, the gas can be discharged from the vent to the recess by the thermal expansion of the molding material. In the molding die according to the present invention, the internal pressure of the molding material injected into the cavity is constant because the cavity in the molding die communicates with the outside of the molding die through the vent, the concave portion and the exhaust portion. Can be maintained. Furthermore, the molding die concerning this invention can remove the hardening body of the molding material hardened | cured inside a vent and a recessed part easily and rapidly. Therefore, according to the present invention, it is possible to provide a molding die having a simple structure capable of forming a flat and highly accurate elastic layer with high reproducibility.

  The molding die according to the present invention is a kind of injection molding die for molding an elastic layer on the outer peripheral surface of a shaft body, and a molding material is filled in a cavity defined inside the molding die. After that, more precisely, when the molding material is heat-molded, an end mold jig having a concave portion continuously disposed in the outer opening of the vent is mounted on the second end mold. It is a mold. The molding die according to the present invention is suitably used, for example, for manufacturing the roller 50 shown in FIG. The roller 50 includes a shaft body 51 and an elastic layer 52 formed on the outer peripheral surface of the shaft body 51.

  As shown in FIG. 1, a molding die 1 as an embodiment of a molding die according to the present invention includes a tubular die 2 into which a shaft body 51 is inserted, and one end portion of the shaft body 51. And the first end mold 3 having the sprue 16 penetrating in the axial direction and the other end of the shaft body 51 are closed. A second end mold 4 for closing the other opening of the tubular mold 2 and an end mold jig 5 attached to the second end mold 4 during heat molding are provided.

  As shown in FIG. 1, the tubular mold 2 is a hollow cylindrical body having openings at both ends, and has a uniform outer diameter and inner diameter. When the elastic layer 52 is formed in the tubular mold 2, the shaft body 51 is inserted along the axial direction thereof. The tubular mold 2 is preferably adjusted to have a surface roughness on its inner surface, and particularly preferably a mirror surface. The outer diameter, inner diameter, axial length, etc. of the tubular mold 2 are adjusted according to the elastic layer 52 to be molded.

  The first end mold 3 holds one end of the shaft body 51 and closes an opening opened at one end of the tubular mold 2. As shown in FIG. 1 and FIG. 2, the first end mold 3 includes a cylindrical end mold body 10 having a holding hole 12 for holding the shaft body 51, and an end mold body 10. It has a disk-like flange portion 11 projecting from one end portion in the circumferential direction and closing the opening of the tubular mold 2, and the flange portion 11 has a thickness smaller than the depth of the holding hole 12 and the thickness direction thereof. And a sprue 16 formed therethrough. In other words, the first end mold 3 is a columnar end mold body 10 having a holding hole 12 provided with a flange-shaped flange 11 that closes one opening of the tubular mold 2. Thus, the thickness of the flange 11 is adjusted to be smaller than the depth of the holding hole 12.

  As shown in FIGS. 1 and 2, the end mold body 10 is opened at one end thereof, and has a bottomed holding hole 12 for holding a shaft body 51, and a cylindrical body having a shared central axis. It is useful for holding one end of the shaft body 51 and determining the contact position of the injection nozzle. The end mold body 10 is adjusted in the axial length, outer diameter, etc., and the depth, diameter, etc. of the holding hole 12 in accordance with the shaft body 51 to be held.

  As shown in FIGS. 1 and 2, the flange portion 11 protrudes in the circumferential direction from one end portion of the end mold body 10 and has a central axis coaxial with the center axis of the end mold body 10. And closes one opening of the tubular mold 2. The flange portion 11 is adjusted to a thickness smaller than the depth of the holding hole 12. Specifically, the thickness of the flange portion 11 is adjusted to about 6 to 25% with respect to the depth of the holding hole 12. When the thickness of the flange portion 11 is adjusted in this way, the axial length of the sprue 16 to be described later is shortened, the remaining amount of the molding material remaining in the sprue 16 is reduced, and the burr formed in the sprue 16 is broken. Can be prevented.

  As shown in FIGS. 1 and 2, the sprue 16 is formed to penetrate in the thickness direction of the flange portion 11 and functions as a passage when the molding material is injected. Since the flange portion 11 has the above thickness, the axial length of the sprue 16 is shortened, the remaining amount of the molding material remaining in the sprue 16 is reduced, and the burrs formed in the sprue 16 are prevented from breaking. Can do. Four sprues 16 are formed at equal intervals on the circumference of a certain distance from the center of the flange portion 11.

  The shape of the vertical cross section (cross section when cut along a plane including the central axis of the flange 11) in the sprue 16 is not particularly limited, and is a substantially rectangular shape extending from the outer end face 14 side to the inner end face 15 side. 1 may be substantially square, but preferably has a trapezoidal shape extending from the outer end face 14 side to the inner end face 15 side, as shown in FIGS. That is, the opening diameter of the inner opening 18 is larger than the opening diameter of the outer opening 17 in the sprue 16. The cross-sectional shape orthogonal to the axis of the sprue 16 may be circular or elliptical. Further, the inner surface of the sprue 16 may be curved in a concave shape or a convex shape.

  As shown in FIG. 1, the second end mold 4 has a structure in which a molding material is injected or a molding material is hardened instead of a sprue 16 that functions as a passage when the molding material is injected. It is configured in the same manner as the first end mold 3 except that a vent 36 that functions as a gas or molding material discharge path is formed in the flange 31. That is, the second end mold 4 projects in a circumferential direction from a columnar end mold main body 30 having a holding hole 32 for holding the shaft body 51, and one end of the end mold main body 30, A disk-shaped flange 31 that closes the opening of the tubular mold 2, and the flange 31 has a thickness smaller than the depth of the holding hole 32 and a vent 36 formed through the thickness direction. It consists of In other words, the second end mold 4 is a cylindrical end mold main body 30 having a holding hole 32 provided with a flange-shaped flange 31 that closes one opening of the tubular mold 2. Thus, the thickness of the flange 31 is adjusted to be smaller than the depth of the holding hole 32. As shown in FIGS. 1 and 2, the vent 36 preferably has a trapezoidal shape extending from the outer end surface 34 side to the inner end surface 35 side, that is, the outer opening in the vent 36, similar to the sprue 16. The opening diameter of the inner opening 38 is preferably larger than the opening diameter of the portion 37. The opening angle of the vent 36 is particularly preferably adjusted to be smaller than the opening angle θ of the sprue 16.

  The end mold jig 5 is used when performing a molding process for molding the elastic layer 52 (that is, a heating process for heating the molding material). That is, the end mold jig 5 will be described later in a cavity 6 (see FIG. 6) composed of the tubular mold 2, the first end mold 3, the second end mold 4, and the shaft body 51. When the molding material is injected, it may or may not be attached to the second end mold 4. However, after the molding material is injected, before the molding process is performed, the second end Mounted on the part mold 4. As shown in FIG. 1, the end mold jig 5 moves the second end mold 4 toward the tubular mold 2 so that the mold 1 is not disassembled by thermal expansion of the molding material. Used to press.

  The end mold jig 5 includes a recess 60 communicating with the outer opening 37 of the vent 36 provided in the second end mold 4, and a bottom portion of the recess 60 (in FIG. 1 and FIG. 3 as a top portion). And an exhaust part 62 extending in the axial direction. As shown in FIG. 3, the end mold jig 5 forms a cylindrical body having substantially the same diameter as the second end mold 4 or the tubular mold 2. The length in the axial direction of the end mold jig 5 is not particularly limited, and is appropriately adjusted according to the length in the axial direction of the end mold body 30 in the second end mold 4. The length in the axial direction of the end mold jig 5 is adjusted, for example, to such a length that a recess 60 having a preferable shape and volume can be formed.

  The recess 60 is formed in the end mold jig 5 as shown in FIGS. 1 and 3. The concave portion 60 is located on the outer end face 34 side of the second end mold 4 and outside the outer openings 37 in the four vents 36 when mounted on the second end mold 4. These vents 36 are communicated with each other. When the recess 60 is formed in this way, even if a gas appears or is generated in the molding material when the molding material is injected into the molding die 1, the gas that has appeared with the molding material surrounding the gas is vented. Thus, the molding material discharged from the vent 36 in this manner can be temporarily stored in the recess 60.

  As shown in FIG. 3 (b), the recess 60 is formed on the outer end face 34 side of the second end mold 4 when the end mold jig 5 is mounted on the second end mold 4. In other words, it is formed so as to be recessed in the axial direction inside the end mold jig 5. The shape of the concave portion 60 is not particularly limited, but the section perpendicular to the axial direction of the end mold jig 5 is a circle or an ellipse, and a hemisphere or an ellipsoid whose diameter gradually decreases in the axial direction. It is preferable that it is in a shape. In other words, the recess 60 preferably forms a part of a sphere or an ellipsoid. If the concave portion 60 is formed in such a shape, the concave portion 60 can be adjusted to a predetermined volume without increasing the size of the end mold jig 5, and the gas present in the vicinity of the vent 36 can be reduced. While being able to remove effectively, the molding material temporarily stored in the recessed part 60 or its hardened | cured material can be removed from the recessed part 60 easily and rapidly.

  The recess 60 is open to one end face of the end mold jig 5, and the opening 61 has a dimension that allows communication with the vent 36. The end mold jig 5 is connected to the second mold jig 5. It is preferable that all the vents 36 have such dimensions that they are located in the opening 61 when mounted on the end mold 4. Specifically, the opening 61 of the recess 60 only needs to have a diameter capable of communicating with the vent 36, and the end mold treatment can be efficiently performed together with the molding material. When the tool 5 is mounted on the second end mold 4, it is preferable that all the vents 36 have such a diameter that they are located in the openings 61. In other words, all the vents 36 are circumscribed. It is preferable to have a diameter larger than the diameter of the virtual circumscribed circle.

  The concave portion 60 only needs to have a volume that can temporarily accommodate the molding material. However, if the volume is too small, the effect of providing the concave portion 60 cannot be expected, and the molding material may flow out. The gas originally present in the recess 60 may flow back into the cavity 6. Therefore, it is desirable that the recess 60 is appropriately determined in consideration of the volume of the cavity 6 and the like. For example, it is preferable that the ratio of the volume with respect to the volume of the cavity 6 is adjusted to 2.0% or more, and the recess 60 is particularly preferably adjusted to 4.0% or more. When the concave portion 60 is adjusted to the volume within the above range, the gas existing inside the concave portion 60 does not flow back into the cavity 6 and the gas existing in the vicinity of the vent 36 even if the flow rate of the molding material varies. The molding material can be temporarily stored. On the other hand, if the volume of the recess 60 is too large, the end mold jig 5 becomes too large, and the handleability may deteriorate. Therefore, the upper limit of the volume of the recess 60 is not particularly limited, but is preferably determined as appropriate in consideration of the volume of the cavity 6 and the like. The upper limit of the volume of the recess 60 is, for example, the ratio of the volume to the volume of the cavity 6 in consideration of forming the recess 60 within the dimensions of the end mold jig 5 and reducing the size of the molding die 1 as a whole. Is preferably adjusted to 10.0%, particularly preferably 7.0%.

  The end mold jig 5 has an exhaust part 62 that extends in the axial direction from the bottom of the recess 60 and penetrates the end mold jig 5. The exhaust part 62 opens in the end mold jig 5 on the end surface of the recess 60 opposite to the opening 61, and the molding material injected into the molding die 1 can be molded in an open system. And also functions as an insertion part for inserting the end mold body 30. Therefore, the exhaust part 62 only needs to be adjusted to an inner diameter larger than the outer diameter of the end mold body 10, and the inner diameter is not particularly limited. When the concave portion 60 has such an exhaust portion 62, the molding material thermally expanded at the time of molding can quickly flow out into the concave portion 60 through the vent 36, and thus appears when the molding material is injected. The discharged gas can be effectively discharged into the recess 60 together with the molding material. Further, when the recess 60 has such an exhaust part 62, the injected molding material is opened through the vent 36, the recess 60 and the exhaust part 62. Therefore, when molding the molding material, In addition, the internal pressure of the molding material injected into the molding die can be kept constant.

  The end mold jig 5 is made of a material having a certain degree of strength and heat resistance at a temperature when the molding material is heat-cured. Examples of such materials include copper, copper alloy, brass, bronze, aluminum, aluminum alloy, steel, various types of plated iron, iron alloy, stainless steel, and the like. The tubular mold 2, the first end mold 3 and the second end mold 4 are preferably formed of the same material, and the end mold jig 5 is formed of the first end mold 3. It is preferably formed of a softer material than the material.

  The concave portion 60 and the exhaust portion 62 can be formed into desired shapes and dimensions by cutting or the like after a cylindrical body is made of the material.

  The molding die 1 is attached to the first end die 3 in addition to the tubular die 2, the first end die 3, the second end die 4, and the end die jig 5. A second end mold jig may be provided. The second end mold jig may be any jig that can press the molding die 1 in the axial direction in a molding process or the like. For example, the end mold jig 5 and FIG. An end mold jig 106 shown in FIG. When the end mold jig 106 is used as the second end mold jig, the sprue 16 in the first end mold 3 can be closed, and the molding injected into the cavity 6 in the molding process. The material does not flow out of the sprue 16, and the molding material thermally expands in one direction toward the vent 36. If it does so, the gas which exists in the vicinity of the vent 36 will be discharged | emitted by the one direction toward the recessed part 60 by the thermal expansion of a molding material, and the gas which exists in the vicinity of the vent 36 can be removed efficiently. In addition, since the molding material thermally expands in one direction toward the vent 36, the gas present in the recess 60 can be effectively prevented from flowing back into the cavity 6.

  As described above, the molding die 1 includes the tubular die 2, the first end die 3, and the second end die 4, and further, the end die treatment that is mounted during heating or the like. The tool 5 is provided, and all these members have a very simple structure. And the recessed part 60, especially the recessed part 60 shape | molded in the shape which comprises a part of ellipsoid can ensure a desirable volume, without enlarging the edge part metal mold | die 5. FIG. Therefore, the molding die 1 can be small and light and have a simple structure.

  In particular, from the viewpoint of manufacturing cost reduction and the like, the molding material injected into the cavity 6 is required to have a small injection amount. Therefore, in consideration of the thermal expansion amount of the molding material, it is common to inject a molding material having a volume slightly larger than the cavity 6 into the cavity 6. For example, the injection amount of the molding material is set so that the volume of the molding material after expansion at the curing temperature of the molding material is about 103.5% with respect to the volume of the cavity 6. As described above, the molding die 1 has the vent 36 having a short axial length and the concave portion 60 connected to the vent 36, preferably the concave portion 60 having a predetermined shape and volume. It is possible to effectively prevent the gas present in the gap in the recess 60 from flowing back into the cavity 6 via the vent 36 by the molding material. Therefore, according to the present invention, it is possible to achieve the object of providing a molding die having a simple structure capable of forming a flat and highly accurate elastic layer with high reproducibility.

  Moreover, since the molding die 1 is formed with the vent 36 in the second end die 4 and the recess 60 is formed in the end die jig 5, the respective functions can be effectively exhibited. This contributes to the miniaturization and simplification of the second end mold 4 and the end mold jig 5. In addition, since the second end mold 4 and the end mold jig 5 have the above-described configuration, a molding material and / or a cured product thereof is contained in the recess 60 of the end mold jig 5. Even if the molding material and / or the cured product thereof remain in the recess 60 without remaining, the remaining can be easily and quickly removed by brushing, for example. Even if the molding material and / or the cured product thereof remains in the vent 36, the remaining material can be easily and quickly removed by brushing, air blowing, or the like.

  Next, an example of a molding method for molding the elastic layer 52 on the outer peripheral surface of the shaft body 51 using the molding die 1 (hereinafter sometimes referred to as a molding method according to the present invention) will be described.

  The molding method according to the present invention includes a tubular mold 2, a first end mold 3 and a second end mold 4, and a first end mold 3 and a second end mold 4. Thus, the molding material is injected through the sprue 16 into the cavity 6 formed by the shaft body 51 held in the tubular mold 2, and the molding material injected into the cavity 6 is heated and cured. And as an example of the roller 50 provided with the elastic layer 52 shape | molded by the shaping | molding method concerning this invention, the roller 50 shown by FIG. 7 is mentioned.

  In the molding method according to the present invention, first, the shaft body 51 is prepared. The shaft 51 includes, for example, a metal such as iron, aluminum, stainless steel, brass, or an alloy thereof, a resin such as a thermoplastic resin or a thermosetting resin, and carbon black or metal powder as a conductivity-imparting agent for the resin. Using a material such as a conductive resin blended with a body or the like, it is produced in a desired shape by a known method. When the shaft body 51 is required to have conductivity, in addition to the metal and the conductive resin, the surface of the insulating core body formed of the resin or the like is plated by a regular method so that the shaft body 51 is Can be produced. Among the above materials, a metal is preferable and aluminum or stainless steel is particularly preferable from the viewpoint that conductivity can be easily imparted. The shaft body 51 may be formed with a primer layer having a thickness of, for example, 0.1 to 10 μm on the outer peripheral surface as desired.

  In the molding method according to the present invention, as shown in FIG. 6, the molding die 1 is then assembled, and the shaft body 51 is accommodated in the molding die 1. In this state, the shaft body 51 is sandwiched between the holding holes 12 of the first end mold 3 and the holding holes 32 of the second end mold 4 at both ends, so that the predetermined end in the molding mold 1 is obtained. The position is fixed.

  In the molding method according to the present invention, an injection molding machine or a casting machine for injecting a molding material is prepared. The molding die 1 according to the present invention, in particular, the first end die 3 has a shape in which the end die body 10 protrudes from the outer end surface 14 of the flange portion 11 as described above. The shape of the injection nozzle in an injection molding machine, a casting machine or the like is produced so as to adapt to the shape of the first end mold 3. That is, the injection nozzle has a shape complementary to the shape of the first end mold 3, for example, as shown in FIG. 8, the end mold body 10 is inserted, and the end mold body 10 and the nozzle tip are inserted. It is produced in an annular shape having a contact positioning recess 41 for determining a contact position with the center 40 and having a molding material injection passage 42 formed through the peripheral wall 43. The injection path 42 is formed at a position corresponding to the position where the sprue 16 of the collar portion 11 is formed.

  In the molding method according to the present invention, the molding material is then injected into the cavity 6 formed by the molding die 1 and the shaft 51 through the sprue 16 of the first end die 3. Any method can be used as the method for injecting the molding material into the cavity 6 as long as it is a regular method. For example, the injection is performed by using an injection molding machine or a casting machine having an injection nozzle tip having the above-mentioned shape. And the like.

  In the molding method according to the present invention, the elastic material 52 is then molded by heat-curing the molding material injected into the cavity 6. At this time, as shown in FIG. 1, the end mold jig 5 is mounted above the second end mold 4. Note that a second end mold jig may be mounted below the first end mold 3. Then, for example, as shown in FIG. 1, the molding die 1 is raised and pressed with a predetermined pressure from the axial direction. While maintaining this state, the molding material is heated to a temperature at which it can be cured. The heating temperature of the molding material is determined according to the molding material. For example, when an addition-curable liquid conductive silicone rubber composition described later is used as a molding material, the heating temperature can be set to 100 to 300 ° C., and the heating time can be set to 10 seconds to 1 hour. it can.

  When the molding die 1 is heated in this way, the entire molding material is thermally expanded even if gas is present in the vicinity of the second end portion mold 4, and the molding material is directed in the direction of the vent 36 and the recess 60. It flows against gravity. If it does so, the gas which appeared in the vicinity of the 2nd edge part metal mold | die 4 will be discharged | emitted by the recessed part 60 via the vent 36 with the molding material of the vicinity. In this way, the gas that appears or exists in the vicinity of the vent 36 is removed from the cavity 6. Further, since the cavity 6 communicates with the outside of the molding die 1 through the vent 36, the concave portion 60 and the exhaust portion 62, the molding material injected into the cavity 6 is molded in an open system, and as a result. The internal pressure generated in the molding material during molding can be kept almost constant. In this way, the elastic layer 52 that is flat and has high deflection accuracy can be formed.

  Even if the molding material remains in the vent 36, the recess 60, and the exhaust portion 62, or the cured material of the molding material exists, the vent 36 has a short length in the axial direction. Alternatively, the cured product can be easily removed. As a result, even if a large number of elastic layers 3 are continuously formed using the molding die 1, the vent 36 is not blocked, so that the elastic layer 52 that is flat and has high runout accuracy is formed with good reproducibility. Can do.

  In particular, if the recess 60 has the preferred shape, the molding material in the recess 60 or a cured body thereof can be easily removed, so the volume of the recess 60 is reduced by the remaining molding material or the cured body thereof. There is nothing to do. Therefore, even if a large number of elastic layers 3 are continuously formed using the molding die 1, the amount of the molding material discharged into the recess 60 can be made constant, so that the elastic layer 52 is flat and has high runout accuracy. Can be formed with higher reproducibility.

  Further, if the concave portion 60 has the volume, for example, even if the heating rate, the injection amount of the molding material, etc. slightly change and the outflow amount of the molding material varies, the concave portion 60 causes these variations. Can be effectively absorbed or offset. Therefore, the cavity 6 (the molding material injected into the cavity 6) is not closed by the molding material flowing into the recess 60, and the elastic layer 52 with high runout accuracy can be formed with higher reproducibility. .

  In this way, the elastic layer 52 can be formed on the outer peripheral surface of the shaft body 51 to manufacture the roller 50 shown in FIG. In the molding method according to the present invention, if desired, it may be heated again (secondary heating) after the heat curing, and the end portion of the molded elastic layer may be cut off if desired.

The roller manufactured by the molding die according to the present invention includes the elastic layer 3 which is flat and has high runout accuracy. The flatness can be evaluated, for example, by visually observing the surface and / or the internal state of the elastic layer 3. The roller manufactured by the molding die according to the present invention has such flatness that a depressed portion or a protruding portion caused by gas cannot be confirmed by visual observation on the surface and / or inside of the elastic layer 3. Moreover, the roller manufactured by the molding die according to the present invention usually has a high runout accuracy of 0.05% or less. Here, the shake accuracy is the accuracy indicating the uniformity of the thickness of the elastic layer 52 in the circumferential direction, that is, the thickness shake (sometimes referred to as shake). The deflection accuracy of the elastic layer 52 is affected by the distance between the center point of the elastic layer 52 and the center point of the shaft body 51. For example, as shown in FIG. 12A, the roller 50 has an elastic layer 52 formed on the outer peripheral surface of the shaft body 51 such that the axis 51C of the shaft body 51 is shifted from the axis in the axial direction. A cross section taken along the line AA of the roller 50 is shown in FIG. Referring to FIG. 12, the deflection accuracy of the elastic layer 52 is the difference (t _max −t _min ) between the maximum thickness (t _max ) and the minimum thickness (t _min ) of the elastic layer 52, in other words, the shaft body 51. The difference (L ₂ −L ₁ ) between the longest distance L ₂ and the shortest distance L ₁ from the axis 51 C to the outer peripheral surface of the elastic layer 52 is expressed as a percentage with respect to the average outer diameter (r _av ) of the elastic layer 52. Calculated as a value.

That is, deflection accuracy of the elastic layer 52 is, for the average outer diameter of the elastic layer 52 (r _av), at least, the maximum thickness of the three points of the center portion and near both ends of the elastic layer 52, the elastic layer 52 (t _max )) and the minimum thickness (t _min ) is a value (t _max −t _min ) expressed as a percentage. More specifically, at each measurement point, the equation [(t _max −t _min ) / R _av ] × 100 (%). Alternatively, the longest distance from the axis 51C of the shaft body 51 to the outer peripheral surface of the elastic layer 52 at least at three points of the central portion and the vicinity of both ends of the elastic layer 52 with respect to the average outer diameter (r _av ) of the elastic layer 52 The difference (L ₂ −L ₁ ) between L ₂ and the shortest distance L ₁ is a value expressed as a percentage. More specifically, at each measurement point, the formula [(L ₂ −L ₁ ) / r _av ] × 100 (%). Here, the deflection accuracy of the elastic layer 52 is determined by measuring the thickness of the elastic layer 52 at each measurement point or the shaft body 51 with a laser length measuring machine while rotating the roller 50 about the central axis of the shaft body 51. The distance from the center point of the elastic layer 52 to the outer peripheral surface of the elastic layer 52 is measured, and can be calculated from the measured maximum thickness and minimum thickness or from the measured longest distance and shortest distance by the above formula.

  Even when a plurality of rollers are manufactured using the molding die according to the present invention, as described above, the elastic layer of each manufactured roller is flat and has a substantially constant runout accuracy.

  The molding material used in the production method according to the present invention may be a rubber composition containing a rubber that is liquid at room temperature. Examples of liquid rubber include silicone or silicone-modified rubber, nitrile rubber, and ethylene propylene rubber ( Ethylene propylene diene rubber), liquid rubbers such as styrene butadiene rubber, butadiene rubber, isoprene rubber, natural rubber, acrylic rubber, chloroprene rubber, butyl rubber, epichlorohydrin rubber, urethane rubber, fluorine rubber and the like. These rubbers are preferably an addition-curing type because they are excellent in dimensional accuracy during heat molding. The rubber composition may contain various additives usually contained in the rubber composition in addition to rubber. Examples of the various additives include vulcanizing agents, vulcanization accelerators, and vulcanization accelerators. Auxiliary agent, vulcanization retarder, conductivity imparting agent, dispersant, foaming agent, anti-aging agent, antioxidant, filler, pigment, colorant, processing aid, softener, plasticizer, emulsifier, curing agent, Examples thereof include a heat resistance improver, a flame retardant improver, an acid acceptor, a heat conductivity improver, a release agent, and a solvent. These various additives may be commonly used additives or may be specially used additives depending on applications. The rubber composition may have a viscosity of, for example, 5 to 500 Pa · s at 25 ° C. in that it can be easily and uniformly injected into the molding die 1, and 10 to 200 Pa · s. It is particularly good to have a viscosity of

Specifically, as such a rubber composition, for example, (A) an organopolysiloxane containing at least two alkenyl groups bonded to a silicon atom in one molecule; and (B) a silicon atom in one molecule. An organohydrogenpolysiloxane containing at least two hydrogen atoms to be bonded; (C) an inorganic filler having an average particle diameter of 1 to 30 μm and a bulk density of 0.1 to 0.5 g / cm ³ ; Examples thereof include an addition-curable liquid conductive silicone rubber composition containing D) a conductivity imparting agent and (E) an addition reaction catalyst.

  The molding die according to the present invention is not limited to the above-described example, and various modifications can be made within a range in which the object of the present invention can be achieved. That is, the shape of the recess 60 is not particularly limited, and may be, for example, a recess 65 that is a rectangular parallelepiped or a cube as shown in FIG. 4A, and a polygonal frustum as shown in FIG. 4B. Or the recessed part 66 which comprises a truncated cone may be sufficient.

  In the molding die 1, the recess 60 is formed as a part of a sphere or an ellipsoid. In the present invention, for example, as shown in FIG. 5, the recess 60 is formed in an annular recess groove 67. May be. Even in this case, it is preferable that the annular concave groove 67 has a shape (spherical surface, elliptical surface) whose upper portion is gradually narrowed, and the volume thereof is preferably within the above range. Further, in the case of the concave groove 67, as shown in FIG. 5, the outer opening 37 of the vent 36 is connected to the inner side of the concave groove 67. It is preferable at the point which can be made to flow out. In this example, two exhaust holes 69 are formed from the bottom of the concave groove 67, and an insertion portion 68 for inserting the end mold body is formed.

  Further, in the molding die 1, the recess 60 is connected to all the vents 36. However, in the present invention, one recess may be connected to one vent, and two or more vents may be provided. One recess may be provided continuously.

  In the molding die 1, the exhaust part 62 also serves as an insertion part into which the end part mold body 30 is inserted. In the present invention, if the end part mold body can be accommodated in the recess, The exhaust part does not need to function as an insertion part for inserting the end mold body. Furthermore, one exhaust part 62 is continuously provided from the bottom of the recess 60. However, in the present invention, one exhaust part is not necessarily provided, and a plurality of exhaust parts may be provided continuously from the recess. .

  Further, the molding die 1 includes a first end die 3 and a second end die 4 having the same structure, and the molding die according to the present invention includes a first end die 3 and a second end die 4. The part mold and the second end mold need not have the same structure.

  Further, the molding die 1 includes a tubular die 2 and a first end portion in which a first end die 3 and a second end die 4 are inserted into both end openings of the tubular die 2. Both ends of the tubular mold are closed by fitting the mold 3 and fitting the tubular mold 2 and the second end mold 4. In the mold, even if both ends of the tubular mold are closed by contacting both end portions of the tubular mold with the inner end surfaces of the flanges in the first end mold and the second end mold. In addition, fitting means such as a flange and an engaging convex portion are formed on the outer edges of the flanges of the first end mold and the second end mold, and at both ends of the tubular mold. For example, fitting means such as a notch and an engaging recess may be formed, and the opening portions at both ends of the tubular mold may be closed by fitting these fitting means.

  Further, in the second end mold 4 constituting the molding die 1, four vents 36 are formed through the flange 31. In this invention, the flange of the second end mold is used. There are no particular restrictions on the number of vents that are formed through, and it may be one or two or more.

Example 1
A molding die 1 shown in FIGS. 1 and 2 was prepared. The tubular mold 2 was formed into a cylindrical shape having a total length of 240 mm, an outer diameter of 35 mm, and an inner diameter of 20.7 mm using NAK55 (plastic mold steel, manufactured by Daido Steel Co., Ltd.). Each of the first end mold 3 and the second end mold 4 uses S50C (steel for machine structure, manufactured by Daido Amister Co., Ltd.), the thickness of the collar 2 mm, the diameter 20.7 mm, the end The length of the part mold body (excluding the thickness of the collar part) was adjusted to 23.0 mm, the depth of the holding hole (including the thickness of the collar part) was 21.0 mm, and the inner diameter was adjusted to 7.5 mm. The sprue and vent are respectively adjusted to have an opening diameter of 2.7 mm at the inner opening and an opening diameter of 2.5 mm (opening angle θ6 °) at the outer opening, and 4 at regular intervals on a circumference of 8 mm from the center of the flange. Individually formed.

As shown in FIG. 3, the end mold jig 5 is a cylinder having an outer diameter of 35.0 mm and an axial length of 25.0 mm using S50C (steel for mechanical structure, manufactured by Daido Amister Co., Ltd.). The recess 60 and the exhaust part 62 were ground. The recess 60 has a diameter of 26.0 mm of the opening 61 and a depth of 13.0 mm (volume 4610 mm ³ : 6.6% with respect to the volume of the cavity 6) to the exhaust portion 62. The exhaust portion 62 has a diameter of 11 The length in the axial direction was 12.0 mm. The second end mold jig mounted on the first end mold 3 is S50C (steel for machine structure, manufactured by Daido Amister Co., Ltd.), and has an inner diameter of 11.0 mm and an axial depth. It was molded into a cylindrical body having an outer diameter of 35 mm and an axial length of 25.0 mm, with a 23.0 mm insertion portion 64 perforated. The inner surface of the tubular mold 2 was polished according to a conventional method.

  Further, the shaft body 51 (made by SUM22, diameter 7.5 mm, length 281.5 mm) subjected to electroless nickel plating treatment was washed with toluene, and a silicone primer (trade name “Primer No. 16”) was formed on the surface thereof. , Manufactured by Shin-Etsu Chemical Co., Ltd.). The shaft body subjected to the primer treatment was fired at a temperature of 150 ° C. for 10 minutes using a gear oven, and then cooled at room temperature for 30 minutes or more to form a primer layer on the surface of the shaft body 51.

Further, an addition curable liquid conductive silicone rubber composition was prepared as follows. That is, 100 parts by mass of dimethylpolysiloxane (A) (degree of polymerization 300) blocked at both ends with dimethylvinylsiloxy groups, and a hydrophobized fumed silica having a BET specific surface area of 110 m ² / g (Nippon Aerosil Co., Ltd.) Made by company, R-972) 1 part by mass, average particle size 6 μm, bulk density of 0.25 g / cm ³ diatomaceous earth (C) (Oplite W-3005S, manufactured by Hokuaki Diatomite Co., Ltd.) 40 parts by mass, and 5 parts by mass of acetylene black (D) (Denka Black HS-100, manufactured by Denki Kagaku Kogyo Co., Ltd.) was put into a planetary mixer, stirred for 30 minutes, and then passed once through three rolls. This is returned to the planetary mixer again, and methylhydrogenpolysiloxane (B) having Si—H groups at both ends and side chains as a crosslinking agent (polymerization degree 17, Si—H amount 0.0060 mol / g) 2. 1 part by mass, 0.1 part by mass of ethynylcyclohexanol as a reaction control agent and 0.1 part by mass of a platinum catalyst (E) (Pt concentration 1%) are added and stirred and kneaded for 15 minutes. The product was a silicone rubber composition. This silicone rubber composition had a viscosity of 60 Pa · s at room temperature (25 ° C.).

  Next, a mold release agent (trade name “Die Free”, manufactured by Daikin Industries, Ltd.) is applied to the inner surface of the formed mold 1, and the holding holes 12 and the second end mold 3 of the first end mold 3 are applied. The shaft 51 is held in the tubular mold 2 by the holding hole 32 of the end mold 4 to assemble the molding mold 1, and the silicone rubber composition from the sprue 16 of the first end mold 3. Was injected to such an extent that it did not flow out of the vent 36 of the second end mold 4.

Next, as shown in FIG. 1, the end mold jig 5 is mounted on the second end mold 4, and the second end mold jig is mounted on the first end mold 3. Then, the molding die 1 was pressed from the axial direction with a pressure of 200 kg / cm ² . While maintaining this state, the silicone rubber composition was heated and molded at 150 ° C. from the outside of the molding die 1 and held at the same temperature for 10 minutes to heat mold the silicone rubber composition. In addition, about 2.6 cm < ³ > of molding material was discharged | emitted in the recessed part 60 of the edge part metal mold | die 5, and several air was contained in the discharged | emitted molding material.

  Next, after the heat molding, the molding die 1 was allowed to cool and the molded product was taken out from the molding die 1. A portion of the sprue 16 and the vent 36 where the surplus material such as burrs cured was attached was cut and removed to produce a roller. In this manner, ten rollers of Example 1 were formed.

(Example 2)
10 rollers of Example 2 were formed in the same manner as Example 1 except that the end mold jig 7 shown in FIG. 4A was used instead of the end mold 5. The end mold jig 7 was formed into a cylindrical body having an outer diameter of 35.0 mm and an axial length of 25.0 mm. As shown in FIG. 4A, the concave portion 65 of the end mold jig 7 has a cylindrical body, the diameter of the opening is 26.0 mm, and the depth to the exhaust portion 62 is 13.0 mm (volume). 6898 mm ³ : 9.8% of the volume of the cavity 6), and the exhaust part 62 had a diameter of 11.0 mm and an axial length of 12.0 mm. Note that after the molding material was heated, about 2.6 cm ³ of the molding material was discharged into the recess 65, and the discharged molding material contained a plurality of air.

(Example 3)
10 rollers of Example 3 were molded in the same manner as Example 1 except that the end mold jig 8 shown in FIG. 4B was used instead of the end mold 5. The end mold jig 8 was formed into a cylindrical body having an outer diameter of 35.0 mm and an axial length of 25.0 mm. As shown in FIG. 4 (b), the recess 66 of the end mold jig 8 has a truncated cone shape with a diameter of 26 mm at the opening and a diameter of 11.1 at the bottom (joining portion with the exhaust part 62). The depth to the exhaust part 62 is 13.0 mm (volume: 3683 mm ³ : 5.3% with respect to the volume of the cavity 6). The exhaust part 62 has a diameter of 11.0 mm and an axial length of 12.0 mm. Met. In addition, after the molding material was heated, about 2.6 cm ³ of the molding material was discharged into the concave portion 66, and the discharged molding material contained a plurality of air.

Example 4
Example 1 except that the volume of the recess 60 was changed to 2172 mm ³ (diameter 27.0 mm of the opening 61, depth 8.9 mm to the exhaust 62: 3.1% with respect to the volume of the cavity 6). Similarly, ten rollers of Example 4 were formed.

(Example 5)
Example 1 except that the volume of the recess 60 was changed to 1173 mm ³ (diameter 27.0 mm of the opening 61, depth 6.0 mm to the exhaust 62: 1.7% with respect to the volume of the cavity 6). Similarly, ten rollers of Example 5 were formed.

(Example 6)
The end mold jig 5 was produced so that the volume of the recess 60 with respect to the cavity was 11.2%. This end mold jig had a slightly larger dimension than the end mold jig of Example 1. Ten rollers of Example 6 were molded in the same manner as Example 1 except that this end mold jig was used.

(Comparative Example 1)
In place of the second end mold 4, the other end mold 110 shown in FIG. 11A (recess 111 connected to the vent 105 (volume 1857 mm ³ : 2.6% with respect to the volume of the cavity 6, Except that a second end mold jig 106 shown in FIG. 10 is used in place of the end mold jig 5. In the same manner as in Example 1, ten rollers of Comparative Example 1 were molded. Note that after the molding material was heated, approximately 1.8 cm ³ of the molding material was discharged into the recess 111, and the discharged molding material contained a plurality of air.

(Comparative Example 2)
The other end mold 112 shown in FIG. 11B is used instead of the second end mold 4 and the second end shown in FIG. 10 is used instead of the end mold jig 5. Ten rollers of Comparative Example 2 were molded in the same manner as Example 1 except that the part mold jig 106 was used. As shown in FIG. 11B, the other end mold 112 is formed into a cylindrical body having an outer diameter of 35.0 mm and an axial length of 25.0 mm, and the insertion section 113 into which the shaft body 2 is inserted. (Diameter 7.5 mm, axial length 5.0 mm), axial length 5.0 mm vent 114 and recess 115 (volume 10613 mm ³ : 15.1% of the cavity 6 volume, diameter 26.0 mm, depth 20.0 mm). Note that after the molding material was heated, approximately 2.5 cm ³ of the molding material was discharged into the recess 115, and the discharged molding material contained a plurality of air. The cured product of the molding material was adhered to the end portion inserted into the insertion portion 113 in the shaft body of the roller thus manufactured.

(Comparative Example 3)
The other end mold 116 shown in FIG. 11C is used instead of the second end mold 4 and the second end shown in FIG. 10 is used instead of the end mold jig 5. Ten rollers of Comparative Example 3 were formed in the same manner as Example 1 except that the part mold jig 106 was used. As shown in FIG. 11C, the other end mold 116 is formed into a cylindrical body having an outer diameter of 35.0 mm and an axial length of 25.0 mm, and the insertion portion 118 into which the shaft body 2 is inserted. (Diameter 7.5 mm, axial length 20.0 mm), axial length 5.0 mm vent 117, and ring-shaped concave groove 119 continuing to vent 118 (volume 7751 mm ³ : volume of cavity 6 And 11.1%, an inner diameter of 13.5 mm, an outer diameter of 26.0 mm, and a depth of 20.0 mm) were formed by grinding. After the molding material was heated, approximately 2.5 cm ³ of the molding material was discharged into the concave groove 119, and a plurality of air was contained in the discharged molding material.

(Comparative Example 4)
An end mold jig similar to the end mold jig 5 of Example 1 was produced except that a non-through insertion hole was formed instead of the exhaust part 62. Ten rollers of Comparative Example 4 were molded in the same manner as in Example 1 except that this end mold jig was used. Note that after the molding material was heated, about 2.4 cm ³ of the molding material was discharged into the recess 62, and the discharged molding material contained a plurality of air.

(Comparative Example 5)
Instead of the end mold jig 5, the second end mold jig forming the cylindrical body produced in Example 1 is used to close the sprue 16 and the vent 36, and the molding mold 1 is closed. 10 rollers of Comparative Example 5 were molded in the same manner as in Example 1 except that was heated.

(Existence of depressions)
The elastic layer of each roller thus formed was visually confirmed. In the evaluation, the presence of the depressed portion in the elastic layer on the second end mold 4 side in all the ten rollers could not be confirmed, and a case where a flat elastic layer was formed was evaluated as “◯”. 2 where the presence of a recess that is small enough to be acceptable in the elastic layer on the side of the end mold 4 is confirmed as “Δ”, and the second end portion of a plurality of 10 rollers. In the case where a plurality of depressions exist on the surface and inside of the elastic layer on the mold 4 side, “X” indicates that there are a large number of the elastic layers on the second end mold 4 side in almost all of the ten rollers. The case where there was a depression was defined as “XX”. The results are shown in Table 1.

(Runout accuracy)
The runout accuracy of the elastic layer of each roller was measured according to the above method. Evaluation is “◎” when the runout accuracy is less than 0.03%, “◯” when the runout accuracy is 0.03% or more and less than 0.05%, and the runout accuracy is 0.05% or more. “△” indicates a case where it is less than 0.06%, “X” indicates a case where the runout accuracy is 0.06% or more and less than 0.08%, and indicates a case where the runout accuracy is 0.08% or more. Xx ”. Note that the runout accuracy in the roller is less than 0.05% within the allowable range. The results are shown in Table 1.

(Variation in runout accuracy)
The variation in the runout accuracy of the rollers manufactured in Examples 1 to 6 was evaluated according to the above method. In the evaluation, when the runout accuracy was a substantially constant value and there was almost no variation, “◎” was given, and when it was slightly scattered, “◯” was given. The results are shown in Table 1.

(Ease of cleaning)
In each of the examples and comparative examples, after the roller was manufactured, air was blown onto the second end mold, and the end mold jig was brushed in the vent and the recess (concave groove). The ease of removal of the cured molding material was evaluated. As a result, the hardened body in the vent and the concave portion can be easily removed by the cleaning operation for a very short time, and the case where the hardened body does not remain in the vent and the concave portion after the cleaning is indicated as “◎”, short. The cured product in the vent and in the recess can be easily removed by the above-mentioned cleaning operation for a long time, and “○” indicates that the cured product does not remain in the vent and the recess after cleaning. When a relatively long time was required to remove the cured product (particularly, the cured product adhered to the corners of the recesses), the case where the cured product did not remain in the vent and the recesses after washing was " Even if the cleaning operation is performed for a long time, the cured product in the vent and the recess (concave groove) cannot be completely removed, and the cured product remains in the vent and the recess (concave groove). did. The results are shown in Table 1.

FIG. 1 is a schematic sectional view showing an example of a molding die according to the present invention. FIG. 2 is a schematic view showing an example of a first end mold constituting the molding die according to the present invention, and FIG. 2A is a first end constituting the molding die according to the present invention. FIG. 2B is a schematic vertical sectional view showing an example of a first end mold constituting the molding die according to the present invention. FIG. 3 is a schematic view showing an example of an end mold jig constituting the molding die according to the present invention, and FIG. 3A is an end mold jig constituting the molding die according to the present invention. It is a schematic bottom view which shows an example of a tool, FIG.3 (b) is a schematic sectional drawing which shows the cross section of the AA line in Fig.3 (a). FIG. 4 is a schematic view showing another example of an end die jig constituting the molding die according to the present invention, and FIG. 4A is an end die constituting the molding die according to the present invention. FIG. 4B is a schematic cross-sectional view showing another example of the end mold jig constituting the molding die according to the present invention. FIG. 5 is a schematic cross-sectional view showing still another example of the end mold jig constituting the molding die according to the present invention. FIG. 6 is a schematic cross-sectional view showing a state in which the shaft body is housed in the molding die according to the present invention. FIG. 7 is a schematic perspective view showing an example of a roller manufactured by the molding die according to the present invention. FIG. 8 is a schematic cross-sectional view for explaining a contact state between the molding die and the nozzle according to the present invention. FIG. 9 is a schematic cross-sectional view showing an example of a conventional molding die. FIG. 10 is a schematic cross-sectional view showing a state when a conventional molding die is subjected to a heating process. FIG. 11 is a schematic cross-sectional view showing the other end mold used in the comparative example, and FIG. 11A is a schematic cross-sectional view showing the other end mold used in comparative example 1. FIG. 11B is a schematic sectional view showing the other end mold used in Comparative Example 2, and FIG. 11C is a schematic sectional view showing the other end mold used in Comparative Example 3. 12A and 12B are explanatory views for explaining the deflection accuracy of the elastic layer, FIG. 12A is a front view of the roller, and FIG. 12B is a cross-sectional view taken along the line AA in FIG. is there.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,100 Molding die 2,101 Tubular die 3 First end die 4 Second end die 5, 7, 8, 9 End die jig 6 Cavity 10, 20, 30 End Mold body 11, 31 鍔 part 12, 32 Holding hole 13, 33 Holding hole bottom face 14, 34 Outer end face 15, 35 Inner end face 16, 104 Sprue 17, 37 Outer opening 18, 38 Inner opening 21 Recessed nozzle positioning 22 Connecting hole 36, 105, 114, 118 Vent 40 Nozzle tip 41 Contact positioning recess 42 Injection path 43 Perimeter wall 50 Roller 51 Shaft 51C Axis 52 Elastic layer 60, 65, 66, 111, 115 Recess 61 Opening 62, 69 Exhaust part 64, 68, 113, 117 Insertion part 67, 119 Groove 102, 110, 112, 116 Other end part mold 103 One end part mold

Claims (1)

A tubular mold in which a shaft body is inserted; a first end mold having a sprue that is formed by penetrating one of the openings in the tubular mold and penetrating in the axial direction; and A second end mold for closing the other opening, and an end mold jig mounted on the second end mold at the time of heat molding,
The second end mold includes an end mold body having a holding hole for holding the shaft body, and a circumference smaller than a depth of the holding hole from one end of the end mold body. Projecting in the direction, and having a flange portion formed with a vent penetrating in the thickness direction,
The end mold jig includes a concave portion communicating with an outer opening of the vent and an exhaust portion extending in the axial direction from the concave portion.

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