Rubber molding die and method for manufacturing rubber molded products

Abstract

To provide a rubber molding mold that reduces occurrence of burrs at a specific place due to a structure of the rubber molding mold, and a method of manufacturing a rubber molded article.SOLUTION: A rubber molding mold 1 is provided with: a first mold; a second mold; a first central core 3 sandwiched between the first mold and the second mold; a second central core 4 insertable / withdrawable with respect to the first central core 3; and a hollow portion 2 which is surrounded by the first mold, the second mold, the first central core 3, and the second central core 4 in a state in which the second central core 4 is inserted into the first central core 3, and into which a rubber material 23 can be injected. In a moving direction when the second central core 4 is being inserted / withdrawn into / from the first central core 3, the first central core 3 side is defined as a first side, and the opposite side is defined as a second side. The first central core 3 is provided with: a first recess 5 formed facing from the second side toward the first side; and a second recess 6 formed facing from the first recess 5 further toward the first side. The first recess 5 is formed with a gap in which the rubber material can flow, between an outer periphery and a tip end of the second central core 4 in a state in which the second central core 4 is inserted.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a rubber mold for rubber molding and a method for manufacturing a rubber molded product using the rubber mold.

Background Art

[0002] Conventionally, rubber molded products in which burrs generated by mold parting can be easily treated, and methods for manufacturing rubber molded products have been proposed. For example, according to the cylindrical rubber molded product and the manufacturing method thereof described in Patent Document 1, in a cylindrical rubber molded product molded by a mold and expanded in diameter by an inner diameter-expanding core inserted inside, the cylindrical rubber molded product has tapered surfaces expanding outward from the minimum inner diameter ends at both end portions thereof. It is described that, when molded by the mold, burrs generated due to circumferential parting of the mold at the position of the maximum inner diameter portion of the tapered surface are ground and removed along the tapered surface.

[0003] According to this, it is described that at least at the end portion expanded in diameter by the inner core of the cylindrical rubber molded product, the molding mold is designed in advance such that the position where burrs occur due to circumferential parting of the mold is located at the maximum inner diameter portion of the tapered surface expanding outward from the minimum inner diameter end, and by grinding and removing generated burrs along the tapered surface, the burrs can be easily and reliably removed. Therefore, even if the cylindrical rubber molded product is subsequently expanded in diameter by the inner core and stored in that state for a long period of time, the situation of cracking at a later date can be avoided.

Prior Art Literature

Patent Literature

[0004]

Patent Literature 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, even if the cylindrical rubber molded product and its manufacturing method shown in Patent Document 1 are configured to easily remove burrs, a so-called post-processing step is required, which increases manufacturing costs. Furthermore, because burr removal is performed in post-processing, there is a possibility of variations in the finished product. In particular, if the burr is located deep inside and difficult to reach with the processing tool, burr removal becomes difficult. In other words, conventional methods have the problems of increased processing time for burr removal and the possibility of variations in quality after burr removal.

[0006] The object of the present invention is to provide a rubber molding die and a method for manufacturing rubber molded products that reduce the generation of burrs at specific locations through the structure of the rubber molding die. [Means for solving the problem]

[0007] A rubber molding die for molding rubber according to a first aspect of the present invention comprises a first mold, a second mold, a first core sandwiched between the first mold and the second mold, a second core that can be inserted into and removed from the first core, and a hollow portion formed surrounded by the first mold, the second mold, and the first and second cores, into which rubber material can be injected, in the state in which the second core is inserted into the first core, the side of the second core in the insertion direction is designated as the first side and the side in the removal direction is designated as the second side in the direction of movement when the second core is inserted into and removed from the first core, the first core comprises a first recess formed from the second side toward the first side, and a second recess formed further toward the first side from the first recess, the second core is insertable into and removed from the first recess, and the first recess forms a gap between the first recess and the outer circumference of the second core in the state in which the second core is inserted, allowing the rubber material to flow.

[0008] According to this, the rubber mold allows the second core to be inserted into and removed from the first recess, and when the second core is inserted, a gap is formed between the first recess and the outer circumference of the second core, allowing the rubber material to flow. When the second core separates from the first core, the rubber material injected into the first and second recesses remains. In the gap between the first recess and the outer circumference of the second core, the rubber material at the mating surface between the first and second cores is cut. Therefore, the rubber mold can suppress the generation of burrs.

[0009] Furthermore, the rubber mold may have protrusions and / or recesses on the inner wall of the second recess in a direction intersecting the insertion and removal direction of the second core.

[0010] In this case, the rubber material remaining in the first and second recesses is prevented from being pulled out when the second core separates from the first core by the protrusions and / or recesses in a direction intersecting the insertion and removal direction of the second core. When the second core separates from the first core, the rubber material remains in the first and second recesses. In the gap between the first recess and the outer circumference of the second core, the rubber material at the mating surface between the first and second cores is cut. Therefore, the rubber molding die can further suppress the generation of burrs.

[0011] A rubber molding die for molding rubber according to a second aspect of the present invention comprises a first mold, a second mold, a first core sandwiched between the first mold and the second mold, a second core that can be inserted into and removed from the first core, and a hollow portion formed surrounded by the first mold, the second mold, and the first and second cores, into which rubber material can be injected, in a state in which the second core is inserted into the first core, the side of the second core in the insertion direction is designated as the first side and the side in the removal direction is designated as the second side in the direction of movement when the second core is inserted into and removed from the first core, the first core has a third recess formed from the second side toward the first side, the third recess has a rubber wall formed along its inner wall, the second core is insertable into and remove from the third recess, and when inserted into the third recess, its outer circumference comes into contact with the rubber wall.

[0012] According to this, a rubber wall is formed along the inner wall of the third recess, and when the second core is inserted into the third recess, its outer circumference comes into contact with the rubber wall. Therefore, the rubber molding die is designed to prevent rubber material from entering between the second core and the third recess, and to suppress the generation of burrs at the mating surface between the first core and the second core.

[0013] A third aspect of the present invention relates to a method for manufacturing a rubber molded product, comprising: a first step of using the rubber mold according to the first aspect, inserting the second core into the first recess; a second step of injecting the rubber material into the hollow portion; a third step of vulcanizing the rubber material; a fourth step of separating the first mold and the second mold, and further separating the first core and the second core; and a fifth step of removing the rubber molded product from the second core.

[0014] According to this, the method for manufacturing rubber molded products involves using a rubber mold and performing four steps from the first to the fourth. Due to the configuration of the rubber mold, the rubber material between the first recess and the second core is cut in the fourth step, so that rubber molded products can be manufactured with suppressed burr formation at the mating surface between the first and second cores.

[0015] Furthermore, the rubber molded product manufacturing method may include the second step of injecting the rubber material into the gap between the first recess and the second core, and into the second recess, the third step of vulcanizing the rubber material injected into the gap in the first recess, and vulcanizing the injected rubber material in the second recess, and the fourth step of separating the second core from the first recess, forming a rubber wall on the inner wall of the first recess, and retaining the vulcanized rubber material in the second recess.

[0016] In this case, the fourth step separates the second core from the first recess, forms a rubber wall on the inner wall of the first recess, and retains the vulcanized rubber material in the second recess. Therefore, when molding rubber molded products in the next generation, it is possible to suppress the entry of rubber material into the first recess, and thus produce rubber molded products in which the generation of burrs at the mating surface between the first core and the second core is suppressed.

[0017] A method for manufacturing a rubber molded article according to a fourth aspect of the present invention is a method for manufacturing a rubber molded article, comprising: using the rubber mold according to the second aspect, a first step of inserting the second core into the third recess; a second step of injecting the rubber material into the hollow portion; a third step of vulcanizing the rubber material; a fourth step of separating the first mold and the second mold, and further separating the first core and the second core; and a fifth step of removing the rubber molded article from the second core, wherein the first step is a step of inserting the second core while in contact with the rubber wall of the third recess.

[0018] According to this method, in the first step, the second core is inserted into the third recess while in contact with the rubber wall, thus preventing rubber material from entering between the third recess and the second core. Therefore, it is possible to manufacture a rubber molded product in which the generation of burrs at the mating surface between the first core and the second core is further suppressed. [Brief explanation of the drawing]

[0019] [Figure 1] This is a plan view of the rubber molding die 1 of the present invention, and a cross-sectional view taken when cut at the parting line position between the first die 11 and the second die 12. [Figure 2] This is a cross-sectional view showing section II in Figure 1. [Figure 3] This is a cross-sectional view showing the procedure for molding a rubber molded product 21 using a rubber mold 1a, with (a) showing the state in which the second core 4 is attached to the first core 3, (b) showing the state in which rubber material 23 is injected into the hollow part 2 and vulcanized, and (c) a cross-sectional view of the rubber molded product 21 removed from the rubber mold 1. [Figure 4]It is an enlarged view of part B in Fig. 3(a), showing the relationship between the first recess 5 and the second core 4, and showing the case where the uneven portion 7 in the second recess 6 is a female thread 7a. [Figure 5] It is a diagram showing the mechanism by which burrs on the mating surface become micro burrs 26 when the first core 3 and the second core 4 are separated from the state shown in Fig. 3(b), wherein (a) shows a state where the rubber molded product 21 is molded, (b) shows a state where the second core 4 is separated from the first core 3 in the direction of the arrow, and (c) shows a state of the hole 24 of the rubber molded product 21 after the rubber molded product 21 is removed from the second core 4. [Figure 6] It is a detailed view of part E in Fig. 5(c). [Figure 7] It is a partial cross-sectional view of the rubber molded product 21 corresponding to Fig. 2. [Figure 8] It is a cross-sectional view showing the case where the uneven portion 7 in the second recess 6 is formed by a protrusion 7b in the rubber molding die 1a of the present invention. [Figure 9] It is a cross-sectional view showing the case where the uneven portion 7 in the second recess 6 is formed by a protrusion 7c with inclination in at least a part thereof in the rubber molding die 1a of the present invention. [Figure 10] It is a cross-sectional view showing the case where there is no uneven portion 7 in the second recess 6 and a straight recess is formed in the direction of the center line C in the rubber molding die 1a of the present invention. [Figure 11] It is a cross-sectional view showing the procedure for molding a rubber molded product 21 by the rubber molding die 1b formed in Fig. 3(c), wherein (a) shows a state where the molded rubber molded product 21 is taken out and the process proceeds to the next molding step, and shows a state where the second core 4 is inserted into the third recess 9, (b) shows a state where a rubber material 23 is injected into the hollow portion 2 and vulcanized, and (c) shows the rubber molded product 21 taken out from the rubber molding die 1. [Figure 12] It is a cross-sectional view showing another example of the rubber molding die 1b. [Figure 13] It is a cross-sectional view showing a conventional rubber molding die 50 as a comparative example, wherein (a) shows a state where a rubber material 23 is injected into the rubber molding die 50 and vulcanized, and (b) shows a main part of a rubber molded product 51 taken out from the rubber molding die 50. [Figure 14] The photographs compare a rubber molded product 51 molded using a conventional rubber mold 50, which is a comparative example, with a rubber molded product 21 molded using the rubber mold 1 of the present invention. (a) shows a burr 56 in the hole 57 of the rubber molded product 51, and (b) shows a minute burr 26 in the hole 24 of the rubber molded product 21. [Modes for carrying out the invention]

[0020] The rubber mold 1 embodying the present invention and the method for manufacturing a rubber molded product will be described below with reference to the drawings. The embodiments for carrying out the invention and the referenced drawings are used to explain the technical features that the present invention may adopt. The present invention is not limited to these. The configurations shown in the drawings are not intended to limit the invention to these configurations, but are merely illustrative examples.

[0021] Figures 1 to 12 show the rubber mold 1 and the method for manufacturing a rubber molded product according to the present invention. The rubber mold 1 has two embodiments: rubber mold 1a as the first embodiment and rubber mold 1b as the second embodiment. Rubber mold 1a and rubber mold 1b have common parts and different parts. The rubber molded product 21 that is molded is the same regardless of whether rubber mold 1a or rubber mold 1b is used.

[0022] <Configuration of rubber molding die 1a> Referring to Figures 1 to 10, a first embodiment of the present invention, a rubber molding die 1a, will be described. The rubber molding die 1a is a mold for molding rubber. The rubber molding die 1a comprises the following: a first mold 11 and a second mold 12. It comprises a first core 3 sandwiched between the first mold 11 and the second mold 12, and a second core 4 that can be inserted into and removed from the first core 3. Furthermore, with the second core 4 inserted into the first core 3, it comprises a hollow portion 2 formed surrounded by the first mold 11, the second mold 12, and the first core 3 and the second core 4, into which rubber material 23 can be injected. As shown in Figure 2, the first mold 11 and the second mold 12 are joined together by contact at a parting line 22. For example, the first core 3 is attached to a first tie bar 13, and the second core 4 is attached to a second tie bar 14.

[0023] As shown in Figure 3, when the second core 4 is inserted into or removed from the first core 3, the side of the second core 4 in the insertion direction is designated as the first side, and the side in the removal direction is designated as the second side. The first core 3 has a first recess 5 formed extending from the second side toward the first side, and a second recess 6 formed further toward the first side from the first recess 5. The second core 4 is insertable into and removeable from the first recess 5. As shown in Figure 4, when the second core 4 is inserted, a gap 8 is formed between the first recess 5 and the outer circumference of the second core 4, allowing the rubber material 23 to flow. In addition, a predetermined space is formed between the tip of the second core 4 and the first recess 5. The center line of the second core 4 in the direction of movement is denoted as C.

[0024] In the example shown in Figure 2, the rubber mold 1a has a first core 3 and a second core 4 sandwiched between the first mold 11 and the second mold 12, and a hollow section 2 is formed when the first mold 11 and the second mold 12 are assembled. For example, the first mold 11 is the lower mold and the second mold 12 is the upper mold. As shown in Figure 1, a gate opening 20 is formed in the hollow section 2, and rubber material 23 is injected into the hollow section 2 from the gate opening 20.

[0025] In the example shown in Figures 1 and 2, the first core 3 is attached by bolts 17, sandwiched between the first tie bar 13, which consists of the lower 13a and upper 13b of the first tie bar. The second core 4 is formed to be movable in the direction of movement relative to the second tie bar 14, which consists of the lower 14a and upper 14b of the second tie bar. As shown in Figure 2, the second core 4 consists of two axial second cores 4a and 4b. When the bolts 18 are tightened, the second cores 4a and 4b are moved to the first side by the second core retainer 19 and inserted into the first recesses 5a and 5b, respectively. When the bolts 18 are loosened, the second core retainer 19 can be removed and the second cores 4a and 4b can be pulled out to the second side. A second recess 6a is formed on the first side of the first recess 5a, and a second recess 6b is formed on the first side of the first recess 5b. As shown in Figure 2, the first recess 5 and the second recess 6 are formed around their respective centerlines C.

[0026] The rubber molded product 21 formed by the rubber mold 1a is, for example, a grommet used in the ABS of an automobile, and as shown in Figure 7, holes 24a and 24b are formed for passing two wire harnesses through. The shape of the rubber molded product 21 is as shown in Figures 3(c), 7, and 11(c), and the second core 4a and second core 4b are for forming holes 24a and 24b, respectively. As shown in Figure 7, etc., there are ribs 25 around holes 24a and 24b.

[0027] Next, the relationship between the first recess 5 of the first core 3 and the second core 4 will be explained with reference to Figure 4. The first end of the second core 4 is formed in an axial shape. The first recess 5 is formed in a cylindrical shape corresponding to the shape of the second core 4, and a gap 8 is formed between the outer circumference of the second core 4 and the first recess 5. The gap 8 is a minute gap that allows the rubber material 23 to flow. The gap 8 is formed to a similar extent between the straight sections 10. When the first core 3 and the second core 4 are separated, the rubber material 23 injected into the first recess 5 and vulcanized is cut at the gap 8 in the straight section 10. A space is formed between the tip of the second core 4 and the first recess 5 so that it connects with the second recess 6 when the rubber material 23 is injected.

[0028] The settings for the gap 8 and the straight section 10 affect the degree of burr formation at the mating surface between the first core 3 and the second core 4. The gap 8 is set to a predetermined gap, and the straight section 10 is set to a predetermined length. If the gap 8 is less than the predetermined gap, the rubber material 23 will not connect easily. Conversely, if it exceeds the predetermined gap, the rubber material 23 will not cut easily when the first core 3 and the second core 4 are separated, and burrs will be more likely to form. Similarly, if the straight section 10 is less than or greater than the predetermined length, the rubber material 23 will not cut easily in the gap 8 when the first core 3 and the second core 4 are separated, and burrs will be more likely to form. The dimensions of the gap 8 and the length of the straight section 10 are set to an optimal range according to various conditions such as the size or shape of the rubber material 23 and the rubber molded product 21 used, and manufacturing conditions.

[0029] Furthermore, the second recess 6 has a protrusion and / or recess on its inner wall in a direction intersecting the insertion and removal direction of the second core 4. Here, the protrusion and / or recess are referred to as the uneven portion 7. The uneven portion 7 provides resistance when the rubber material 23 is pulled out in the direction from the first side to the second side, as the rubber material 23 fits into it. The uneven portion 7 can take on various forms. In the examples shown in Figures 1 to 5, at least a part of the uneven portion 7 of the second recess 6 has the shape of a female screw 7a. As another example, as shown in Figure 8, the uneven portion 7 may be a protrusion 7b formed in part of the second recess 6. As yet another example, as shown in Figure 9, the uneven portion 7 may be a protrusion 7c formed with an inclination in part of the second recess 6. The protrusion 7c is formed in a tapered shape, widening on the first side and narrowing towards the second side.

[0030] Furthermore, as shown in Figure 10, the second recess 6 may be straight along the center line C without any unevenness 7. In this case, minute irregularities may be formed on the surface of the inner circumferential wall of the second recess 6 so that the vulcanized rubber material 23 does not slip easily. Also, the second recess 6 may have a sufficient length along the center line C so that resistance is generated when the vulcanized rubber material 23 is pulled out from the second recess 6.

[0031] <Effects of rubber molding die 1a> The rubber molding die 1a described above provides the following effects. As shown in Figures 3 and 4, the rubber molding die 1a allows the second core 4 to be inserted into and removed from the first recess 5, and when the second core 4 is inserted, a gap 8 is formed between the first recess 5 and the outer circumference of the second core 4, allowing the rubber material 23 to flow. When the second core 4 separates from the first core 3, the rubber material 23 injected into the first recess 5 and the second recess 6 remains. Furthermore, in the gap 8 between the first recess 5 and the outer circumference of the second core 4, the rubber material 23 at the mating surface between the first core 3 and the second core 4 is cut. Therefore, the rubber molding die 1a can suppress the generation of burrs.

[0032] Furthermore, as shown in Figure 3, etc., the rubber material 23 remaining in the first recess 5 and the second recess 6 is prevented from being pulled out when the second core 4 separates from the first core 3 by the uneven portion 7. When the second core 4 separates from the first core 3, the rubber material 23 remains in the first recess 5 and the second recess 6. In the gap 8 between the first recess 5 and the outer circumference of the second core 4, the rubber material 23 at the mating surface between the first core 3 and the second core 4 is cut. Therefore, the rubber molding die 1a can further suppress the generation of burrs. As will be described in more detail later, when rubber molding is performed next time, the rubber material 23 is prevented from entering the first recess 5, so the rubber molding die 1a can suppress the generation of burrs at the mating surface between the first core 3 and the second core 4.

[0033] Furthermore, as shown in Figure 4, the rubber material 23 injected into the second recess 6 is retained in the first recess 5 and the second recess 6 by the uneven portion 7 having the shape of a female screw 7a, so that when the second core 4 separates from the first core 3, the rubber material 23 remains in the first recess 5 and the second recess 6, further suppressing outflow. When the second core 4 separates from the first core 3, the rubber material 23 remains in the first recess 5 and the second recess 6. In the gap 8 between the first recess 5 and the outer circumference of the second core 4, the rubber material 23 at the mating surface between the first core 3 and the second core 4 is cut. Therefore, the rubber molding die 1a can further suppress the generation of burrs. As will be described in detail later, when rubber molding is performed next time, the entry of rubber material 23 into the first recess 5 will be suppressed, so the rubber molding die 1a can suppress the generation of burrs at the mating surface between the first core 3 and the second core 4.

[0034] Furthermore, even if no irregularities 7 are formed in the second recess 6, the rubber material 23 may remain inside the second recess 6. For example, as shown in Figure 10, if the second recess 6 is formed to be sufficiently long along the center line C, the outflow of the rubber material 23 may be suppressed by the frictional resistance between the rubber material 23 and the inner wall of the second recess 6 when the rubber material 23 is pulled out. Alternatively, the outflow may be suppressed by forming minute irregularities on the inner wall of the second recess 6 that create frictional resistance between the rubber material 23 and the irregularities.

[0035] <Regarding burrs on the mating surface between the first core 3 and the second core 4 in the rubber molding die 1a> Next, with reference to Figures 4 and 5, burrs on the mating surface between the first core 3 and the second core 4 in the rubber mold 1a will be described. Figure 5(a) shows the state in which a rubber molded product 21 is molded using the rubber mold 1a. Rubber material 23 is injected into the second recess 6 continuously from the first recess 5 and vulcanized. As shown in Figure 4, a gap 8 is formed in a straight section 10 of a predetermined length, and rubber material 23 is injected into the gap 8 and vulcanized.

[0036] As shown in Figure 5(b), when the first core 3 and the second core 4 are separated, the rubber material 23 injected into the first core 3 and the second core 4b remains in place. Section D indicates the mating surface between the first core 3 and the second core 4b. The rubber material 23 injected into the gap 8 is pulled and cut when the first core 3 and the second core 4 are separated. At this time, the rubber material 23 is cut between the straight sections 10.

[0037] As shown in Figure 5(c), the rubber molded product 21 removed from the second core 4 has burrs generated in the holes 24 that form minute burrs 26 around the ribs 25 at approximately uniform heights, as shown in Figure 6. This is because the rubber material 23 injected into the second recess 6 remains without being pulled out when the first core 3 and the second core 4 separate, and is cut at the gap 8 in the straight section 10.

[0038] <Configuration of rubber molding die 1b> Next, a rubber molding die 1b according to a second aspect of the present invention will be described. The rubber molding die 1b is a mold for molding rubber. As shown in Figures 11 and 12, the rubber molding die 1b comprises the following: a first mold 11 and a second mold 12; a first core 3 sandwiched between the first mold 11 and the second mold 12; and a second core 4 that can be inserted into and removed from the first core 3. Furthermore, with the second core 4 inserted into the first core 3, a hollow portion 2 is formed surrounded by the first mold 11, the second mold 12, and the first core 3 and the second core 4, into which rubber material 23 can be injected.

[0039] When the second core 4 is inserted into or removed from the first core 3, the side of the second core 4 in the insertion direction is designated as the first side, and the side in the removal direction is designated as the second side. The first core 3 has a third recess 9 formed from the second side toward the first side. A rubber wall 9a is formed along the inner wall of the third recess 9, and the second core 4 can be inserted into and removed from the third recess 9. When the second core 4 is inserted into the third recess 9, its outer circumference comes into contact with the rubber wall 9a. For example, as shown in Figure 2, the first core 3 is attached to the first tie bar 13, and the second core 4 is attached to the second tie bar 14.

[0040] Figures 11 and 12 show the rubber mold 1b. The example of the rubber mold 1b shown in Figure 11 is in a state where rubber material 23 has been injected into and remains in the second recess 6, and the first recess 5 in the rubber mold 1a has been replaced by the third recess 9. The method for manufacturing the rubber molded product will be described later, but in this case, the rubber mold 1b can be formed by molding the rubber molded product 21 using the rubber mold 1a and then removing the rubber molded product 21 from the first core 3 and the second core 4.

[0041] The example shown in Figure 11(a) shows the state in the rubber mold 1a after the second core 4 has been removed from the state in Figure 3(b). In other words, it shows the state after the rubber molded product 21 has been molded using the rubber mold 1a, which is the rubber mold 1b. In the example shown in Figure 11, there is a second recess 6 on the second side of the third recess 9, a rubber wall 9a is formed in the third recess 9, and vulcanized rubber material 23 is filled in the second recess 6.

[0042] The example of the rubber mold 1b shown in Figure 12 lacks the portion corresponding to the second recess 6 of the rubber mold 1a, and the first recess 5 is replaced by the third recess 9. In this case, the third recess 9 is formed in the rubber mold 1b without going through the process of molding the rubber molded product 21 using the rubber mold 1a. In the rubber mold 1b, the rubber wall 9a of the third recess 9 is formed to match the shape of the tip of the second core 4.

[0043] <Effects of rubber molding die 1b> The rubber molding die 1b described above provides the following effects. A rubber wall 9a is formed along the inner wall of the third recess 9, and when the second core 4 is inserted into the third recess 9, its outer circumference comes into contact with the rubber wall 9a. Therefore, the rubber molding die 1b prevents the rubber material 23 from entering between the second core 4 and the third recess 9, and suppresses the generation of burrs at the mating surface between the first core 3 and the second core 4.

[0044] <Regarding burrs on the mating surface between the first core 3 and the second core 4 in the rubber molding die 1b> Next, with reference to Figure 11, we will describe the burrs on the mating surface between the first core 3 and the second core 4 in the rubber mold 1b. As shown in Figure 11(a), a rubber wall 9a is formed on the inner circumferential wall of the third recess 9, and when the tip of the second core 4 is inserted into the third recess 9, the outer circumference of the second core 4 contacts the rubber wall 9a and adheres tightly by vulcanization molding. The rubber wall 9a may also be in contact with the second core 4 with elastic deformation.

[0045] As shown in Figure 11(b), when the rubber material 23 is injected into the hollow portion 2, the second core 4 and the third recess 9 are in close contact, so the entry of the rubber material 23 is suppressed. The rubber wall 9a has already been vulcanized and molded, so it adheres tightly to the third recess 9 and does not fall off. As a result, the entry of the rubber material 23 is suppressed at the mating surface between the first core 3 and the second core 4, so as shown in Figure 11(c), when the rubber molded product 21 is removed from the rubber mold 1b, the generation of burrs around the hole 24 is suppressed. Although the explanation of how burr generation is suppressed has been given with reference to Figure 11, the same applies to the example in Figure 12.

[0046] <Description of the third embodiment of the method for manufacturing rubber molded products> Next, a method for manufacturing a rubber molded product according to a third aspect of the present invention will be described. The method for manufacturing a rubber molded product uses the rubber mold 1a according to the first aspect already described. As shown in Figure 3(a), the method for manufacturing a rubber molded product comprises a first step of inserting the second core 4 into the first recess 5, a second step of injecting rubber material 23 into the hollow portion 2 as shown in Figure 3(b), and a third step of vulcanizing the rubber material 23. Furthermore, it comprises a fourth step of separating the first mold 11 and the second mold 12, separating the first core 3 and the second core 4, and a fifth step of removing the rubber molded product 21 shown in Figure 3(c) from the second core 4.

[0047] Furthermore, the second step of the rubber molded product manufacturing method includes injecting rubber material 23 into the gap 8 between the first recess 5 and the second core 4, and into the second recess 6. The third step includes vulcanizing the rubber material 23 injected into the gap 8 in the first recess 5, and vulcanizing the injected rubber material 23 in the second recess 6. As shown in Figure 5(b), the fourth step involves separating the second core 4 from the first recess 5, forming a rubber wall 9a on the inner wall of the first recess 5, and retaining the vulcanized rubber material 23 in the second recess 6.

[0048] <Effects of the third embodiment of the method for manufacturing rubber molded products> The rubber molded product manufacturing method according to the third embodiment described above provides the following effects. As shown in Figure 3, the rubber molded product manufacturing method uses a rubber mold 1a and performs the first to fourth steps to mold the rubber molded product 21. As shown in Figure 5(b), in the fourth step, when the first core 3 and the second core 4 are separated, the vulcanized rubber material 23 remains in the second recess 6. In the gap 8 between the first recess 5 and the outer circumference of the second core 4, the rubber material 23 between the first recess 5 and the second core 4 is cut, and the generation of burrs at the mating surface between the first core 3 and the second core 4 is suppressed. Therefore, a rubber molded product 21 with suppressed burr generation can be manufactured.

[0049] <Description of the fourth embodiment of the method for manufacturing a rubber molded product> Next, a method for manufacturing a rubber molded product according to a fourth aspect of the present invention will be described. As shown in Figure 11(a), the method for manufacturing a rubber molded product uses the rubber mold 1b according to the second aspect already described. As shown in Figure 11(a), the method for manufacturing a rubber molded product according to the fourth aspect comprises a first step of inserting the second core 4 into the third recess 9, a second step of injecting rubber material 23 into the hollow portion 2 as shown in Figure 11(b), and a third step of vulcanizing the rubber material 23. Furthermore, it comprises a fourth step of separating the first mold 11 and the second mold 12 and separating the first core 3 and the second core 4, and a fifth step of removing the rubber molded product 21 from the second core 4 as shown in Figure 11(c). The first step is the step of inserting the second core 4 while in contact with the rubber wall 9a of the third recess 9.

[0050] As previously explained, the rubber mold 1b may be the same one used after the rubber molded product 21 has been formed using the rubber mold 1a, as shown in Figure 11. Alternatively, as shown in Figure 12, it may be a mold that has been formed directly without going through the process of forming the rubber molded product 21 using the rubber mold 1a.

[0051] <Effects of the fourth embodiment of the method for manufacturing rubber molded products> The rubber molded product manufacturing method according to the fourth embodiment described above provides the following effects. As shown in Figure 11(a), in the first step, the second core 4 is inserted into the third recess 9 in contact with the rubber wall 9a, so that the entry of rubber material 23 between the third recess 9 and the second core 4 can be suppressed. Therefore, a rubber molded product 21 can be manufactured in which the generation of burrs at the mating surface between the first core 3 and the second core 4 is further suppressed. The same applies when the rubber mold 1b is the example shown in Figure 12.

[0052] <Differences in burr generation between comparative example and rubber molding die 1 of the present invention> Next, we will compare the state of burr formation by comparing the rubber molded product 21 formed by the rubber mold 1 of the present invention with the rubber molded product 51 formed by a conventional rubber mold 50, which is a comparative example. The molding process for the rubber molded product 21 using the rubber mold 1 has already been described. Figure 13 shows the case of the rubber molded product 51, which is a comparative example.

[0053] Figure 13(a) shows the state after the rubber material 23 has been injected into the hollow section 2 and vulcanized. The rubber mold 50 does not have a second recess 6 like the present invention, and only the first recess 55 is formed in the first core 53. Also, unlike the rubber mold 1b, the first recess 55 does not have a rubber wall 9a formed in the rubber mold 1b. Figure 13(b) shows the state after the first core 53 has been removed from the second core 54. The rubber material 23 that filled the first recess 55 comes out of the first recess 55 while still connected to the rubber molded product 51, and remains as a burr 56. The burr 56 is removed by manual processing.

[0054] Figure 14(a) shows the state in which the burrs 56 in the hole 57 of a conventional rubber molded product 51 have been removed by manual processing, and Figure 14(b) shows the state of minute burrs 26 in the hole 24 of a rubber molded product 21 made by the rubber mold 1a of the present invention.

[0055] As shown in Figure 14, the conventional rubber molded product 51 has variations in the burrs 56 removed by manual processing, resulting in partial unevenness. In contrast, the rubber molded product 21 according to the present invention has only minute burrs 26, resulting in less unevenness and a lower height compared to the conventional rubber molded product 51. In other words, with the rubber mold 1 according to the present invention, there is no need to deburr after molding, and even if there are burrs, they are only minute burrs 26. Note that the burr state shown in Figure 14(b) is the case when using the rubber mold 1a of the present invention, but the condition is similar when using the rubber mold 1b. [Explanation of Symbols]

[0056] 1, 1a, 1b Rubber molding mold 2 Hollow part 3 First core 4, 4a, 4b Second core 5, 5a, 5b First recess 6, 6a, 6b Second recess 7 Uneven part 8 gaps 9 Third recess 9a Rubber wall 11 Type 1 12 Second type 21. Molded rubber products 23 Rubber materials

Claims

1. A rubber molding die for molding rubber, Type 1 and Type 2 and A first core sandwiched between the first type and the second type, A second core that can be inserted into and removed from the first core, With the second core inserted into the first core, the first mold, the second mold, and the first and second cores form a hollow section into which rubber material can be injected, With respect to the first core, in the direction of movement when the second core is inserted into or removed from the first core, the side of the second core in the insertion direction is designated as the first side, and the side in the removal direction is designated as the second side. The first core mentioned above is A first recess formed from the second side toward the first side, It comprises a second recess formed further toward the first side from the first recess, The second core is removable from the first recess. The first recess, when the second core is inserted, forms a gap between it and the outer circumference of the second core. The gap is formed between the first recess and the second core, with a predetermined gap dimension and approximately the same length, between the predetermined length of the straight section formed between them. The predetermined gap dimension is a minute gap that allows the rubber material to flow. A rubber molding die in which, when the first core and the second core are separated, the rubber material injected into the first recess and vulcanized is cut at the gap in the straight portion.

2. The rubber molding die according to claim 1, wherein the inner wall of the second recess has a convex portion and / or a recess in a direction intersecting the insertion and removal direction of the second core.

3. A rubber molding die for molding rubber, Type 1 and Type 2 and A first core sandwiched between the first type and the second type, A second core that can be inserted into and removed from the first core, With the second core inserted into the first core, the first mold, the second mold, and the first and second cores form a hollow section into which rubber material can be injected, With respect to the first core, in the direction of movement when the second core is inserted into or removed from the first core, the side of the second core in the insertion direction is designated as the first side, and the side in the removal direction is designated as the second side. The first core mentioned above is It includes a third recess formed from the second side toward the first side, The third recess is, A rubber wall is formed along the inner wall. The second core is insertable into and removeable from the third recess, and when inserted into the third recess, its outer circumference comes into contact with the rubber wall in this rubber molding die.

4. A method for manufacturing a rubber molded product, Using the rubber molding die described in claim 1 or 2, The first step is to insert the second core into the first recess, A second step involves injecting the rubber material into the hollow portion, A third step of vulcanizing the rubber material, A fourth step involves separating the first type and the second type, and further separating the first core and the second core, A method for manufacturing a rubber molded product, comprising a fifth step of removing the rubber molded product from the second core.

5. The second step includes injecting the rubber material into the gap between the first recess and the second core, and into the second recess. The third step is, The first recess includes a step of vulcanizing the rubber material injected into the gap, The second recess includes a step of vulcanizing the injected rubber material, The method for manufacturing a rubber molded product according to claim 4, wherein the fourth step involves separating the second core from the first recess, forming a rubber wall on the inner wall of the first recess, and securing the vulcanized rubber material in the second recess.

6. A method for manufacturing a rubber molded product, Using the rubber mold described in claim 3, The first step is to insert the second core into the third recess, A second step involves injecting the rubber material into the hollow portion, A third step of vulcanizing the rubber material, A fourth step involves separating the first type and the second type, and further separating the first core and the second core, The fifth step involves removing the rubber molded product from the second core, The first step is a method for manufacturing a rubber molded product, wherein the first step is a step of inserting the second core while in contact with the rubber wall of the third recess.

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