Double-layer rubber sand clock spring forming mold and method

Abstract

A double-layer rubber hourglass spring forming die comprises an upper die body, a lower die body, a core die body, a plurality of inserts spliced on the periphery of the core die body and clamped between the upper die body and the lower die body, and a middle die body sleeved on the inserts in a conical surface fit mode, a cover plate cavity used for containing a cover plate of an hourglass spring is formed in the bottom face of the upper die body, and a bottom plate cavity used for containing a bottom plate of the hourglass spring is formed in the top face of the lower die body. A rubber cavity is formed between the inserts and the core mold, an inner layer injection runner extending to the core mold and communicated with the rubber cavity is formed in the upper mold, the inserts are divided into the first insert used for forming a conventional rubber layer and the second insert used for forming a fireproof rubber layer, and the first insert and the second insert are sequentially matched with the conical surface of the middle mold. An insert runner which can be communicated with the rubber cavity is formed in the second insert; and a middle mold runner which can be communicated with the insert runner is formed in the middle mold. According to the invention, injection molding and synchronous molding of two kinds of rubber in the same mold are realized, and the molding efficiency and quality of the hourglass spring are improved. The invention further provides a forming method of the double-layer plastic hourglass spring.

Description

Technical Field

[0001] The present invention relates to a double-layer rubber hourglass spring forming die and method, belonging to the technical field of hourglass spring forming. Background Art

[0002] In order to achieve flame retardancy for the rubber material in the metal-rubber hourglass spring, a large amount of flame retardant needs to be added. However, the addition of the flame retardant will seriously deteriorate the basic physical properties of the rubber in the metal-rubber hourglass spring, such as tensile, elastic and fatigue properties, resulting in difficulty in passing the fatigue test of the hourglass spring, and there is a contradiction between the flame retardant property and the physical property. In order to enable the hourglass spring to have both good elastic vibration damping performance and fatigue performance, and good fire and flame retardant performance, a flame retardant rubber layer wrapped outside the conventional rubber is used to improve the fire and flame retardant performance of the hourglass spring, so that the hourglass spring has both good elastic vibration damping performance and fatigue performance, and good fire and flame retardant performance. This is a good method to avoid adding flame retardants to the conventional rubber and achieve the fire and flame retardant performance. However, in the prior art, most of them prefabricate the conventional rubber layer and the fireproof rubber layer separately, and then place the preformed two-layer rubber into the die for vulcanization to realize the sulfur combination of the two-layer rubber. When prefabricating the conventional rubber layer and the fireproof rubber layer, prefabrication dies are required respectively, and when sulfur-combining the preformed two-layer rubber, a vulcanization die is used. This process of preforming the fireproof rubber and the conventional rubber and then vulcanizing them together mainly has the following problems: 1. The process of prefabrication and then vulcanization combination is complicated, the operation is complex, the time consumption is long, and the forming efficiency is low.

[0003] 2. The prefabricated conventional rubber layer and fireproof rubber layer are prone to breakage or deformation during the demolding and mold loading processes, affecting the quality and appearance of the formed hourglass spring; moreover, the thickness of the fireproof rubber layer is small, it is difficult to shape, and the difficulty of demolding and mold loading after preforming is large, and the proficiency requirement for the operator is high.

[0004] 3. The requirements for the die and equipment are high, and the types and quantities of dies are many, and the workload of cleaning the die rubber after demolding is large. Summary of the Invention

[0005] The double-layer rubber hourglass spring forming die provided by the present invention avoids the complicated process of prefabricating the inner and outer rubber layers separately, simplifies the forming process of the hourglass spring, reduces the types and quantities of dies, ensures the integrity of the inner and outer rubber layers, improves the quality of the hourglass spring, reduces the workload of die rubber cleaning, realizes the injection molding and synchronous modeling of the two rubbers in the same die, improves the forming efficiency and quality of the hourglass spring, and the forming process is simple and easy to operate. The present invention also provides a double-layer rubber hourglass spring forming method.

[0006] To achieve the above object, the technical solution adopted by the present invention is: Double-layer glue hourglass spring forming die, including an upper die, a lower die, a core die clamped between the upper die and the lower die, inserts that are multi-petal assembled on the outer periphery of the core die and clamped between the upper die and the lower die, and a middle die that is tapered and fitted over the inserts. A cover plate cavity for accommodating the cover plate of the hourglass spring is provided on the bottom surface of the upper die, and a bottom plate cavity for accommodating the bottom plate of the hourglass spring is provided on the top surface of the lower die. A rubber cavity is formed between the inserts and the core die. An inner injection runner extending to the core die and communicating with the rubber cavity is provided on the upper die. It is characterized in that: the inserts are divided into a first insert for forming a conventional rubber layer and a second insert for forming a fireproof rubber layer. The first insert and the second insert are successively tapered and fitted with the middle die. A runner is provided in the second insert that can communicate with the rubber cavity, and a middle die runner that can communicate with the insert runner is provided on the middle die.

[0007] Preferably, the second insert and the first insert have the same shape, the outer diameters of the first insert and the second insert are equal, and the inner diameter of the second insert is larger than the inner diameter of the first insert.

[0008] Preferably, an outer injection runner communicating with the middle die runner and located on the outer periphery of the inner injection runner is provided on the upper die.

[0009] Preferably, a through injection channel communicating the inner injection runner and the outer injection runner is provided on the top surface of the upper die. A runner connection valve that can control the communication or disconnection between the inner injection runner and the outer injection runner is installed in the through injection channel. The runner connection valve is located in the through injection channel between the inner injection runner and the outer injection runner.

[0010] Preferably, the insert runners radially penetrate the second insert and there are multiple of them. The middle die runner is a groove opened on the inner wall of the middle die from top to bottom. The outer ends of the insert runners are all communicated with the middle die runner.

[0011] Preferably, the outer periphery of the lower die has a positioning convex ring protruding outward, and both the first insert and the second insert have positioning grooves that cooperate with the positioning convex ring.

[0012] Double-layer glue hourglass spring forming method, using the double-layer glue hourglass spring forming die described above, is characterized in that: it includes the following steps: S1: Place the cover plate on the cover plate cavity, place the bottom plate in the bottom plate cavity, multi-petal assemble the first insert on the outer periphery of the core die, and then taper and fit the middle die over the first insert to form a closed die; S2: Inject conventional rubber into the inner injection runner, and the conventional rubber fills the rubber cavity to form a conventional rubber layer; S3: Perform preliminary shaping on the conventional rubber layer under the condition that the rubber does not undergo a cross-linking reaction; S4: Open the mold and demold the first insert block. Assemble the multi - petal second insert block around the outer periphery of the core mold. Then, fit the middle mold conical surface over the second insert block and connect the middle mold runner with the insert block runner to form a closed mold, creating an annular space between the inner surface of the second insert block and the conventional rubber layer. S5: Inject fire - resistant rubber into the middle mold runner. The fire - resistant rubber enters the annular space through the insert block runner and fills the annular space to form a fire - resistant rubber layer outside the conventional rubber layer. S6: Heat up and vulcanize to form the hourglass spring, and then cool down and demold after vulcanization to obtain the hourglass spring.

[0013] Preferably, "injecting conventional rubber into the inner - layer injection runner" means: closing the runner connection valve to disconnect the inner - layer injection runner from the outer - layer injection runner, and injecting conventional rubber into the inner - layer injection runner from the through - hole injection channel.

[0014] Preferably, "injecting fire - resistant rubber into the middle mold runner" means opening the runner connection valve to connect the outer - layer injection runner with the inner - layer injection runner, injecting fire - resistant rubber from the through - hole injection channel, and the fire - resistant rubber enters the middle mold runner through the through - hole injection and the outer - layer injection runner.

[0015] The beneficial effects of the invention are: In the double - layer rubber hourglass spring forming mold of the present invention, the insert block is divided into a first insert block and a second insert block. The multi - petal first insert block can form a conical fit with the middle mold, and the multi - petal second insert block can also form a conical fit with the middle mold. During the forming process, the first insert block and the second insert block are successively in conical fit with the middle mold. When the first insert block is in conical fit with the middle mold, conventional rubber is injected into the rubber cavity through the inner - layer injection runner to form a conventional rubber layer. After the conventional rubber layer is initially shaped, the first insert block is demolded, and then the second insert block is in conical fit with the middle mold. Fire - resistant rubber is injected into the insert block runner to form a fire - resistant rubber layer outside the conventional rubber layer. The inner and outer layers of rubber are vulcanized synchronously to form the hourglass spring. The injection, forming, and vulcanization of the inner and outer layers of rubber are completed in one mold, avoiding the complicated process of pre - forming the inner and outer layers of rubber separately, eliminating the pre - forming mold, simplifying the forming process of the hourglass spring, reducing the types and quantities of molds, eliminating the demolding and mold - loading of the pre - formed rubber layer, avoiding damage or deformation of the pre - formed rubber layer due to demolding and mold - loading, ensuring the integrity of the inner and outer rubber layers, improving the quality of the hourglass spring, reducing the workload of mold cleaning, realizing the injection molding and synchronous molding of the two rubbers in the same mold, improving the forming efficiency and quality of the hourglass spring, with a simple forming process and easy operation. Description of the Drawings

[0016] Figure 1 It is a schematic diagram of the double - layer rubber hourglass spring forming mold when the first insert block is in conical fit with the middle mold.

[0017] Figure 2 It is a schematic diagram of the double - layer rubber hourglass spring forming mold when the second insert block is in conical fit with the middle mold. Detailed implementation mode

[0018] The following will Figures 1-2 make a detailed description of the embodiments of the present invention.

[0019] The double-layer rubber hourglass spring forming die includes an upper die 1, a lower die 2, a core die 3 clamped between the upper die 1 and the lower die 2, inserts that are multi-petal assembled on the outer periphery of the core die 3 and clamped between the upper die 1 and the lower die 2, and a middle die 5 that is in conical fit with the inserts. A cover plate cavity 11 for accommodating the cover plate of the hourglass spring is provided on the bottom surface of the upper die 1, and a bottom plate cavity 21 for accommodating the bottom plate of the hourglass spring is provided on the top surface of the lower die 2. A rubber cavity 6 is formed between the inserts and the core die 3. An inner layer injection runner 7 extending to the core die 3 and communicating with the rubber cavity 6 is provided on the upper die 1. It is characterized in that: the inserts are divided into a first insert for forming a conventional rubber layer and a second insert for forming a fireproof rubber layer. The first insert 41 and the second insert 42 are in conical fit with the middle die 5 in sequence. A runner 421 that can communicate with the rubber cavity 6 is provided in the second insert 42, and a middle die runner 51 that can communicate with the runner 421 is provided on the middle die 5.

[0020] In the double-layer rubber hourglass spring forming die described above, the inserts are divided into a first insert 41 and a second insert 42. The multi-petal assembled first insert 42 can form a conical fit with the middle die 5, and the multi-petal assembled second insert 42 can also form a conical fit with the middle die. During the forming process, the first insert 41 and the second insert 42 are in conical fit with the middle die 5 in sequence. When the first insert 41 is in conical fit with the middle die 5, conventional rubber is injected into the rubber cavity 6 through the inner layer injection runner 7 to form a conventional rubber layer. After the conventional rubber layer is initially shaped, the first insert 41 is demolded, and then the second insert 42 is in conical fit with the middle die 5. Fireproof rubber is injected into the runner 421 to form a fireproof rubber layer outside the conventional rubber layer. The inner and outer layer rubbers are vulcanized synchronously to form an hourglass spring. The inner and outer layer rubbers complete injection, forming, and vulcanization in one die, avoiding the complicated process of pre-forming the inner and outer layer rubbers separately, eliminating the pre-forming die, simplifying the forming process of the hourglass spring, reducing the types and quantities of dies, eliminating the demolding and mold loading of the pre-formed rubber layer, avoiding damage or deformation of the pre-formed rubber layer due to demolding and mold loading, ensuring the integrity of the inner and outer rubber layers, improving the quality of the hourglass spring, reducing the workload of die cleaning, realizing the injection molding and synchronous molding of the two rubbers in the same die, improving the forming efficiency and quality of the hourglass spring, and the forming process is simple and easy to operate.

[0021] Among them, the second insert block 42 and the first insert block 41 have the same shape, the outer diameters of the first insert block 41 and the second insert block 42 are equal, and the inner diameter of the second insert block 42 is larger than that of the first insert block 41. When the second insert block 42 is in tapered fit with the middle mold 5, the radial dimension of the rubber cavity 6 formed is larger than that when the first insert block 41 is in tapered fit with the middle mold. That is to say, when the first insert block 41 is in tapered fit with the middle mold 5, the conventional rubber fills the rubber cavity 6 to form a conventional rubber layer. Then, the first insert block 41 is demolded. When the second insert block 42 is in tapered fit with the middle mold, since the inner diameter of the second insert block 42 is larger than that of the first insert block 41, an annular gap will be formed between the second insert block 42 and the conventional rubber layer. The fireproof rubber enters from the insert runner 421 and fills the annular gap between the second insert block 42 and the conventional rubber layer, thus forming a fireproof rubber layer B outside the conventional rubber layer A. Therefore, the second insert block 42 and the first insert block 41 have the same shape but different inner diameter dimensions to create the space required for forming the fireproof rubber layer B between the conventional rubber layer A and the second insert block 41. By adjusting the inner diameter of the second insert block 42, the thickness of the fireproof rubber layer can be adjusted.

[0022] Among them, an outer injection runner 8 communicating with the middle mold runner 51 and located outside the inner injection runner 7 is provided on the upper mold 1. When the second insert block 42 is in tapered fit with the middle mold 5, the fireproof rubber enters the insert runner 421 through the outer injection runner 8 and the middle mold runner 5. The provision of the outer injection runner 8 on the upper mold 1 makes the injection operation of the fireproof rubber more convenient.

[0023] Among them, a through injection channel 9 communicating the inner injection runner 7 and the outer injection runner 8 is provided on the top surface of the upper mold 1. A runner connection valve 10 for controlling the connection or disconnection between the inner injection runner 7 and the outer injection runner 8 is installed in the through injection channel 9. The runner connection valve 10 is located in the through injection channel 9 between the inner injection runner 7 and the outer injection runner 8. When the first insert block 41 is in tapered fit with the middle mold 5, the conventional rubber is injected from the through injection channel 9. At this time, the runner connection valve 10 is closed, and the conventional rubber will not flow into the outer injection runner 8. When the second insert block 42 is in tapered fit with the middle mold 5, the runner connection valve 10 is opened, and the fireproof rubber is injected into the through injection channel 9. At this time, the inner injection runner 7 has been filled with the conventional rubber, so the fireproof rubber can only enter the outer injection runner 8 from the through injection channel 9. The setting of the runner connection valve 10 enables both the conventional rubber and the fireproof rubber to be injected from the through injection channel on the top surface of the upper mold 1, making the operation simpler, shortening the injection path, improving the injection efficiency, and reducing the workload of mold cleaning.

[0024] Among them, the insert runner 421 penetrates the second insert 42 radially and there are multiple of them. The middle mold runner 51 is a groove opened on the inner wall of the middle mold 5 from top to bottom. The outer ends of the insert runners are all connected to the middle mold runner. When the fireproof rubber material enters the middle mold runner 51, it will respectively enter into multiple insert runners 421, enter the rubber cavity 6 from the insert runners 421, and form a fireproof rubber layer B outside the conventional rubber layer A. The multiple insert runners 421 improve the injection efficiency and ensure the thickness uniformity of the fireproof rubber layer, thereby improving the molding efficiency and quality. The middle mold runner 51 is formed simply on the inner wall of the middle mold 5 and is convenient for removing the glue.

[0025] Among them, the outer periphery of the lower mold 1 has a positioning convex ring 12 protruding outward. Both the first insert 41 and the second insert 42 have positioning grooves that cooperate with the positioning convex ring 12. The cooperation between the positioning groove and the positioning convex ring 12 positions the first insert 41 or the second insert 42 on the lower mold 1, preventing the middle mold from pulling the first insert 41 or the second insert 42 upward when the mold is opened upward. At the same time, the cooperation between the positioning convex ring 12 and the positioning groove forms a position guide for the multi-piece splicing of the first insert 41 or the second insert 42, improving the splicing efficiency of the inserts.

[0026] The present invention also protects a method for forming a double-layer rubber hourglass spring, which uses the above-mentioned double-layer rubber hourglass spring forming mold, and is characterized in that it includes the following steps: S1: Place a cover plate on the cover plate cavity 11, place a bottom plate in the bottom plate cavity 21, multi-piece splice the first insert 41 around the core mold 3, and then sleeved the middle mold 5 on the first insert 41 by conical surface fitting to form a closed mold; S2: Inject conventional rubber into the inner layer injection runner 7, and the conventional rubber fills the rubber cavity 6 to form a conventional rubber layer A; S3: Perform preliminary shaping on the conventional rubber layer without the rubber undergoing a cross-linking reaction; S4: Open the mold and demold the first insert 41, multi-piece splice the second insert around the core mold 3, and then sleeved the middle mold 5 on the second insert 41 by conical surface fitting and connect the middle mold runner 51 with the insert runner 421 to form a closed mold, forming an annular interval between the inner surface of the second insert 42 and the conventional rubber layer A; S5: Inject fireproof rubber into the middle mold runner 51, and the fireproof rubber enters the annular interval through the insert runner 421 and fills the annular interval to form a fireproof rubber layer B outside the conventional rubber layer A; S6: Heat up and vulcanize to form the hourglass spring, and cool down and demold after sulfurization to obtain the hourglass spring.

[0027] In the above-described double-layer rubber hourglass spring forming method, when the first insert block 41 is in tapered fit with the middle die 5, conventional rubber is injected into the rubber cavity 6 through the inner injection runner 7 to form a conventional rubber layer. After the conventional rubber layer is preliminarily shaped, the first insert block 41 is demolded, and then the second insert block 42 is in tapered fit with the middle die 5. Fireproof rubber is injected into the insert runner 421 to form a fireproof rubber layer outside the conventional rubber layer. The inner and outer layer rubbers are vulcanized synchronously to form an hourglass spring. The inner and outer layer rubbers complete injection, forming, and vulcanization in one mold, avoiding the complicated processes of pre-forming the inner and outer layer rubbers separately, eliminating the prefabrication molds, simplifying the forming process of the hourglass spring, reducing the types and quantities of molds, eliminating the demolding and mold loading of the prefabricated rubber layer, avoiding the damage or deformation of the prefabricated rubber layer due to demolding and mold loading, ensuring the integrity of the inner and outer rubber layers, improving the quality of the hourglass spring, reducing the workload of mold rubber cleaning, realizing the injection molding and synchronous molding of the two rubbers in the same mold, improving the forming efficiency and quality of the hourglass spring, and the forming process is simple and easy to operate.

[0028] Among them, "injecting conventional rubber into the inner injection runner 7" means: closing the runner connection valve 10 to disconnect the inner injection runner 7 from the outer injection runner 8, and injecting conventional rubber into the inner injection runner 7 from the through injection runner 9. When the first insert block 41 is in tapered fit with the middle die 5, conventional rubber is injected from the through injection runner 9. At this time, the runner connection valve 10 is closed, and the conventional rubber will not flow into the outer injection runner 8.

[0029] Among them, "injecting fireproof rubber into the middle die runner" means opening the runner connection valve 10 to connect the outer injection runner 8 with the inner injection runner 7, and injecting fireproof rubber from the through injection runner 9. The fireproof rubber is injected into the middle die runner 51 through the through injection 9 and the outer injection runner 8. When the second insert block 42 is in tapered fit with the middle die 5, the runner connection valve 10 is opened, and fireproof rubber is injected into the through injection runner 9. At this time, the inner injection runner 11 has been filled with conventional rubber, so the fireproof rubber can only enter the outer injection runner 8 from the through injection runner 9 and enter the middle die runner 51 from the outer injection runner 8. Both the conventional rubber and the fireproof rubber can be injected from the through injection runner 10 on the top surface of the upper die 1, which is simpler to operate, can also shorten the injection path, and improve the injection efficiency.

[0030] The technical solutions of the embodiments of the present invention are completely described above in conjunction with the accompanying drawings. It should be noted that the described embodiments are only a part of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

Claims

1. A double-layer rubber hourglass spring forming mold, comprising an upper mold, a lower mold, a core mold sandwiched between the upper mold and the lower mold, an insert with multiple petals assembled on the outer periphery of the core mold and sandwiched between the upper mold and the lower mold, and a middle mold with a conical surface fitted on the insert, a cover plate cavity for accommodating a cover plate of the hourglass spring is provided on the bottom surface of the upper mold, a bottom plate cavity for accommodating a bottom plate of the hourglass spring is provided on the top surface of the lower mold, a rubber cavity is formed between the insert and the core mold, and an inner layer injection flow channel extending to the core mold and connected to the rubber cavity is provided on the upper mold, characterized in that: The inserts are divided into a No. 1 insert for forming a conventional rubber layer and a No. 2 insert for forming a fireproof rubber layer. The No. 1 insert and the No. 2 insert are successively matched with the cone surface of the middle mold. The No. 2 insert is provided with an insert flow channel that can be connected to the rubber cavity, and the middle mold is provided with a middle mold flow channel that can be connected to the insert flow channel.

2. The double-layer rubber hourglass spring forming mold according to claim 1, characterized in that: The second insert has the same shape as the first insert, the outer diameters of the first insert and the second insert are equal, and the inner diameter of the second insert is greater than the inner diameter of the first insert.

3. The double-layer rubber hourglass spring forming mold according to claim 1, characterized in that: The upper mold is provided with an outer injection flow channel which is connected with the middle mold flow channel and is located on the periphery of the inner injection flow channel.

4. The double-layer rubber hourglass spring forming mold according to claim 3, characterized in that: A through injection channel connecting the inner layer injection channel and the outer layer injection channel is provided on the top surface of the upper mold, and a channel connecting valve is installed in the through injection channel to control the connection or disconnection of the inner layer injection channel and the outer layer injection channel. The channel connecting valve is located in the through injection channel between the inner layer injection channel and the outer layer injection channel.

5. The double-layer rubber hourglass spring forming mold according to claim 1, characterized in that: The insert flow channel radially penetrates the second insert and is multiple in number. The middle mold flow channel is a groove opened on the inner wall of the middle mold from top to bottom. The outer ends of the insert flow channels are connected to the middle mold flow channels.

6. The double-layer rubber hourglass spring forming mold according to claim 4, characterized in that: The outer periphery of the lower mold is provided with a positioning convex ring protruding outwards, and both the No. 1 insert and the No. 2 insert are provided with a positioning groove matched with the positioning convex ring.

7. A method for forming a double-layer rubber hourglass spring, using the double-layer rubber hourglass spring forming mold according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1: placing a cover plate on the cover plate cavity, placing a bottom plate in the bottom plate cavity, assembling multiple petals of the No. 1 insert on the outer periphery of the core mold, and then fitting the conical surface of the middle mold on the No. 1 insert to form a closed mold; S2: injecting conventional rubber into the inner layer injection channel, so that the conventional rubber fills the rubber cavity to form a conventional rubber layer; S3: Preliminary shaping of the conventional rubber layer without cross-linking reaction of the rubber; S4: opening the mold and demoulding the No. 1 insert, assembling the multiple petals of the No. 2 insert on the outer periphery of the core mold, and then fitting the conical surface of the middle mold on the No. 2 insert and connecting the flow channel of the middle mold with the flow channel of the insert to form a closed mold, and forming an annular gap between the inner surface of the No. 2 insert and the conventional rubber layer; S5: injecting fireproof rubber into the middle mold flow channel, the fireproof rubber enters the annular space through the insert flow channel and fills the annular space outside the conventional rubber layer to form a fireproof rubber layer; S6: Heating and vulcanizing to form the hourglass spring, and then cooling and demoulding to obtain the hourglass spring.

8. The double-layer rubber hourglass spring forming method according to claim 7, characterized in that: "Injecting conventional rubber into the inner layer injection channel" means: closing the channel connection valve to disconnect the inner layer injection channel from the outer layer injection channel, and injecting conventional rubber into the inner layer injection channel from the through injection channel.

9. The double-layer rubber hourglass spring forming method according to claim 8, characterized in that: "Injecting fire-resistant rubber into the middle mold runner" means opening the runner connection valve to connect the outer layer injection runner with the inner layer injection runner, injecting the fire-resistant rubber from the through injection runner, and injecting the fire-resistant rubber into the middle mold runner through the through injection and outer layer injection runner.

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