Size control method of rubber vulcanization product

Abstract

A size control method of a rubber vulcanized product comprises the following steps: firstly determining the size of the rubber vulcanized product in practical application, then determining the shrinkage rate of rubber in a manufacturing process, and then setting the size of a space for injecting rubber in a mold according to the shrinkage rate of the rubber, so as to determine the size of the mold for producing the rubber vulcanized product. Therefore, a rubber vulcanized product meeting the design size requirement is produced. The total shrinkage rate of a rubber vulcanization product is accurately determined from six aspects influencing the rubber shrinkage rate, and the size of a space for injecting rubber in a mold is accurately calculated through a formula according to the actual size of the product to be produced, so that the size of the product after mold stripping can be highly close to the design size of the product, and the production efficiency is improved. Therefore, the precision of a rubber vulcanization product is greatly improved, and the performance requirement of a high-precision product is ensured.

Description

Technical Field

[0001] The invention relates to a rubber vulcanized product in the field of rail transit, and in particular to a method for controlling the size of the rubber vulcanized product by shrinkage rate. Background Art

[0002] The vulcanization of rubber and metal is mostly done in a mold, but the molten rubber will shrink after being injected into the mold and cooled, making the actual product size smaller than the size when the product was designed. When the product requires low precision, the actual product size is slightly smaller than the size when the product was designed, and the product can be used. Or, based on experience, the space for injecting rubber into the mold can be designed to be slightly larger, and the size tolerance of the rubber vulcanized product after cooling and shrinking is not too large compared to the size when the product was designed, and the product can also be used. However, for some rubber metal spherical bearings with high precision requirements, if the actual size of the product has a large difference from the size tolerance when the ideal product was designed, it will seriously affect the stiffness curve and product performance of the rubber metal spherical bearing. Summary of the invention

[0003] The technical problem to be solved by the present invention is: how to produce a rubber vulcanized product with a size highly close to that of the product design, so as to ensure that the excellent performance of the rubber vulcanized product with high precision requirements is not affected.

[0004] In view of the above problems, the technical solution proposed by the present invention is: a method for controlling the size of a rubber vulcanized product, which first determines the size of the rubber vulcanized product in actual application, then determines the shrinkage rate of the rubber in the manufacturing process, and then sets the size of the space for injecting the rubber in the mold according to the shrinkage rate of the rubber, thereby determining the size of the mold for producing the rubber vulcanized product, thereby producing a rubber vulcanized product that meets the design size requirements.

[0005] Preferably, the determination of the shrinkage rate of rubber during the manufacturing process includes the following 6 aspects: A: The shrinkage rate is determined according to the temperature during vulcanization; B: Determine the shrinkage rate based on the amount of sulfur used; C: Determine the shrinkage rate based on the glue content; D: Determine the shrinkage rate based on the hardness of the rubber; E: Determine the shrinkage rate based on the amount of raw material injected; F: Determine the shrinkage rate according to the type of rubber; After the shrinkage rates of the above six aspects are determined, the total shrinkage rate is obtained by adding up the six shrinkage rates.

[0006] Preferably, according to the size of the rubber required after cooling in the rubber vulcanized product, the relationship between the size of the rubber and the size of the space for injecting the rubber in the mold is expressed by formula (1): K=(Dg-Dz) / Dz*100% (1) Wherein, K is the total shrinkage of the rubber to be vulcanized, Dg is the size of the space in the mold into which the rubber is injected at room temperature, and Dz is the size of the rubber portion of the rubber vulcanized product at room temperature; Formula (2) can be derived: Dg=K*Dz+Dz (2) From formula (2), it can be seen that when the total shrinkage rate K and the size Dz of the rubber in the rubber vulcanized product are determined, the size Dg of the space for injecting rubber into the mold can be determined, thereby designing the shape and size of the mold.

[0007] Preferably, after the shape and size of the mold are designed, the mold and the components in the rubber vulcanized product are assembled into a closed space for injecting rubber, and then molten rubber is injected into the closed space. After the rubber is cooled, the rubber vulcanized product is demoulded and taken out, so that the size of the produced rubber vulcanized product meets the design requirements.

[0008] Preferably, the rubber vulcanized product includes a core shaft, a rubber layer and a jacket, and the mold for producing the rubber vulcanized product includes a flap mold, a partition, an upper insert, a lower insert, an upper mold, a rubber injection cylinder, a middle mold and a lower mold; the core shaft, the jacket, the upper insert and the lower insert are together surrounded to form a closed space for injecting rubber.

[0009] Preferably, expansion grooves are provided on the lower surface of the upper insert and the upper surface of the lower insert, and the expansion grooves on the surfaces of the upper insert and the lower insert are respectively recessed toward the interior of the upper insert and the lower insert; and the expansion grooves on the surfaces of the upper insert and the lower insert are arranged in a closed space for injecting rubber surrounded by the core shaft, the outer sleeve, the upper insert and the lower insert. When the molten rubber is injected into the closed space, bulges are formed at both ends of each petal-type rubber layer in the vertical direction. When the molten rubber is cooled and the rubber layer shrinks, the bulges formed at both ends in the vertical direction will gradually become flat.

[0010] Preferably, the middle mold is arranged between the upper mold and the lower mold, and a glue injection cylinder is arranged between the upper mold and the middle mold, a groove is opened at the bottom of the glue injection cylinder, and an upper insert is arranged in the groove; a through mounting hole is opened in the middle mold, and a petal mold and a partition are arranged in the mounting hole of the middle mold, the petal mold is arranged on the outside of the outer sleeve in the circumferential direction, and the partition is arranged on the outside of the core shaft in the circumferential direction, and a circular groove is opened in the lower mold, and a lower insert is arranged in the circular groove.

[0011] Preferably, the mold is assembled first, a closed space for injecting rubber is formed in the mold, and then molten rubber is injected into the closed space of the mold, and the rubber vulcanized product is removed from the mold after the rubber is cooled, wherein the mold assembly steps include: S1. First install the split lower insert into the lower mold, and then install the mandrel onto the lower insert; S2. Sequentially place the petal-type jacket and partition on the upper surface of the lower panel; S3. Close the petal mold; S4. Assemble the split upper insert and the mandrel; S5. Assemble the middle mold and inject the rubber cylinder; S6. Place the rubber plug and the upper mold in sequence to complete the mold installation.

[0012] Preferably, the molten rubber is injected into the closed space of the mold by opening a through injection hole on the injection cylinder and the upper insert, injecting the molten rubber into the mold through the injection hole of the injection cylinder and the upper insert, so that the molten rubber is injected into the gap between the core shaft and the outer sleeve, thereby vulcanizing the core shaft and the outer sleeve into a whole with the rubber, and forming a rubber vulcanized product with dimensions meeting the design requirements after cooling.

[0013] The beneficial technical effects of the present invention are: 1. The total shrinkage of rubber vulcanized products is accurately determined from the six aspects that affect the shrinkage of rubber, and the size of the space for injecting rubber in the mold is accurately calculated through the formula according to the actual size of the product to be produced, so that the size of the product after demolding can be highly close to the design size of the product, thereby greatly improving the accuracy of rubber vulcanized products and ensuring the performance requirements of high-precision products.

[0014] 2. In view of the fact that the rubber layer of the split-type rubber metal joint bearing is large in the vertical direction and is prone to depression after cooling and shrinkage, expansion grooves are set on the surface of the split-type upper and lower inserts to form bulges at both ends of the molten rubber layer in the vertical direction. After cooling, the bulges shrink to fill the depressions in the vertical direction, so that the two ends of the rubber layer of the product in the vertical direction can become flat after cooling. This further improves the precision of rubber vulcanized products and ensures the performance requirements of high-precision products. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a vertical cross-sectional schematic diagram of the overall structure of Embodiment 1; Figure 2 It is a schematic diagram of the overall structure decomposition of the first embodiment; Figure 3 It is a structural schematic diagram of the glue injection cylinder of the first embodiment; Figure 4 It is a structural schematic diagram of the upper insert of the first embodiment; Figure 5 It is a structural schematic diagram of the lower insert of the first embodiment; In the figure: upper mold 1, glue injection plug 2, glue injection cylinder 3, annular groove 31, center column 32, external glue injection hole 33, petal mold 4, outer sleeve 5, rubber layer 6, partition 7, upper insert 8, upper positioning hole 81, waist-shaped groove 82, internal glue injection hole 83, lower insert 9, external positioning ring 91, internal positioning protrusion 92, telescopic groove 93, core shaft 10, middle mold 11, lower mold 12. DETAILED DESCRIPTION

[0016] The present invention will be further described below in conjunction with embodiments and drawings: Embodiment 1

[0017] like Figure 1 and Figure 2 As shown, this embodiment uses a mold to produce a rubber metal joint bearing, and the metal joint bearing includes a core shaft 10, a rubber layer 6 and a jacket 5. The mold for producing the rubber metal joint bearing includes an upper mold 1, a glue injection plug 2, a glue injection cylinder 3, a middle mold 11, a flap mold 4, a partition 7, an upper insert 8, a lower insert 9, and a lower mold 12. The middle mold 11 is arranged between the upper mold 1 and the lower mold 12, the glue injection cylinder 3 is arranged between the upper mold 1 and the middle mold 11, and the glue injection plug 2 is placed in the glue injection cylinder 3. A groove is opened at the bottom of the glue injection cylinder 3, and an upper insert 8 is arranged in the groove. A split flap mold 4 and a partition 7 are arranged in the mounting hole of the middle mold 11. A circular groove is opened in the lower mold 12, and a lower insert 9 is arranged in the circular groove. The core shaft 10 passes through the mounting hole of the middle mold 11, and the split flap jacket 5 is also arranged in the mounting hole of the middle mold 11, and the outer side of the jacket 5 is tightly attached to the inner side of the flap mold 4.

[0018] like Figure 1 , Figure 3 and Figure 4 As shown, an annular groove 31 is formed on the upper surface of the glue injection cylinder 3, so that a columnar center column 32 is formed inside the annular groove 31. The glue injection plug 2 is in the shape of a circular tube, and the glue injection plug 2 is placed in the annular groove 31, and the glue injection plug 2 is sleeved on the center column 32. An external glue injection hole 33 is formed at the bottom of the annular groove 31 and passes through the glue injection cylinder 3, and the external glue injection holes 33 are evenly distributed in the circumferential direction of the annular groove 31. The upper mold 1 presses the glue injection plug 2 in the annular groove 31, so that the glue injection plug 2 blocks all the external glue injection holes 33.

[0019] The upper insert 8 is a split-petal insert. In the present embodiment, the upper insert 8 is divided into four independent petals. A through upper positioning hole 81 is provided in the middle of the upper insert 8. A waist-shaped groove 82 is provided in the circumferential direction on the outer side of the upper positioning hole 81. Each waist-shaped groove 82 is provided with an inner glue injection hole 83 that passes through the upper insert 8 on the side close to the upper positioning hole 81. The inner glue injection hole 83 gradually decreases in diameter from top to bottom. In the present embodiment, there are six inner glue injection holes 83 on the upper insert 8, and the outer sleeve 5, the petal mold 4 and the partition 7 are all three-petal. Each outer sleeve 5 is respectively surrounded by the partition 7, the core shaft 10, the upper insert 8 and the lower insert 9 to form a small closed space, and each small closed space is connected to two inner glue injection holes 83. The molten rubber is injected into the closed space through the outer glue injection hole 33 of the glue injection cylinder 3 and the inner glue injection hole 83 of the upper insert 8. The molten rubber forms a rubber layer 6 in the closed space, that is, Figure 1 The area with oblique hatching.

[0020] like Figures 1 to 4 As shown, the lower insert 9 is a petal insert. In this embodiment, the lower insert 9 and the upper insert 8 are symmetrical structures, and the lower insert 9 is also divided into four independent petals. An upwardly protruding, annular inner positioning protrusion 92 is provided in the middle of the upper surface of the lower insert 9, and a mounting hole that passes through the inner positioning protrusion 92 and the upper insert 8 is opened on the inner positioning protrusion 92. An annular outer positioning ring 91 and a strip-shaped telescopic groove 93 are also provided on the upper surface of the lower insert 9. The outer positioning ring 91 is arranged on the outer side of the inner positioning protrusion 92, and the height of the outer positioning ring 91 is less than the height of the inner positioning protrusion 92. The inner side of the top and bottom of the partition 7 is provided with a structure corresponding to the inner positioning protrusion 92 and the outer positioning ring 91 of the lower insert 9, so that the outer side of the inner positioning protrusion 92 and the outer positioning ring 91 are completely fitted with the inner side of the partition 7, and the partition 7 is limited in the radial direction.

[0021] The expansion grooves 93 of the upper insert 8 and the lower insert 9 are both arranged on the outside of the outer positioning ring 91, and the length direction of the expansion grooves 93 is the radial direction of the outer positioning ring 91. The expansion grooves 93 on the surfaces of the upper insert 8 and the lower insert 9 are respectively recessed into the upper insert 8 and the lower insert 9, and the expansion grooves 93 on the surfaces of the upper insert 8 and the lower insert 9 are both arranged in a closed space for injecting rubber surrounded by the mandrel 10, the outer sleeve 5, the upper insert 8 and the lower insert 9. When the expansion grooves 93 are not provided on the surfaces of the upper insert 8 and the lower insert 9, since the size of the rubber layer 6 in the rubber metal spherical bearing in the vertical direction is large, the top and bottom of the rubber layer 6 are easy to be recessed inward after cooling and shrinking.

[0022] After the expansion grooves 93 are provided on the surfaces of the upper insert 8 and the lower insert 9, when the molten rubber is injected into the closed space, bulges are formed at both ends of each petal-type rubber layer 6 in the vertical direction. When the molten rubber is cooled and the rubber layer 6 shrinks, the bulges formed at both ends in the vertical direction will gradually become flat, so that the product shape is normal.

[0023] In this embodiment, the rubber vulcanized product is an integral component formed by vulcanizing the core shaft 10, the rubber layer 6 and the outer sleeve 5, and the integral component is the core component of the rubber metal spherical bearing. The specific process of producing the core component of the rubber metal spherical bearing by using a mold is as follows: First, according to the vehicle's stiffness curve requirements for the rubber metal spherical bearing, the specific shape and size of the ideal rubber metal spherical bearing, especially the specific shape and size of the rubber vulcanized product and the rubber layer 6, are designed, so that the size of the rubber vulcanized product in actual application is determined.

[0024] The size required for the rubber vulcanized product in practical application refers to the overall size of the rubber vulcanized product composed of the core shaft 10 and the outer sleeve 5 after the rubber layer 6 vulcanizes the core shaft 10 and the outer sleeve 5 together and cools down. In addition to the overall size of the rubber vulcanized product, the size of the rubber layer 6 itself is also very important. Because the overall size of the rubber vulcanized product will affect the assembly size of the rubber vulcanized product. If the actual size of the rubber vulcanized product is larger than the design size, the rubber vulcanized product may be too large and cannot be installed; if the actual size of the rubber vulcanized product is smaller than the design size, the rubber vulcanized product may be too small and easy to loosen after assembly, which seriously affects the performance of the rubber vulcanized product.

[0025] Then, it is necessary to determine the shrinkage rate of the rubber during the manufacturing process. In this embodiment, the determination of the shrinkage rate of the rubber during the manufacturing process includes the following six aspects: A: The shrinkage rate is determined according to the vulcanization temperature: the higher the vulcanization temperature, the greater the rubber shrinkage rate. The shrinkage rate is determined according to the specific vulcanization temperature. B: Determine the shrinkage rate based on the amount of sulfur used: When the amount of sulfur used is about 3%, the shrinkage rate of the rubber is about 1.5~2%; when the amount of sulfur used is about 15%, the shrinkage rate can reach 4%. The shrinkage rate is determined based on the actual amount of sulfur used; C: Determine the shrinkage rate based on the glue content: the higher the glue content, the greater the shrinkage rate. The shrinkage rate is determined based on the actual glue content used; D: Determine the shrinkage rate based on the hardness of the rubber compound: Generally, the lower the hardness, the greater the shrinkage rate; the higher the hardness, the smaller the shrinkage rate. The shrinkage rate is determined based on the actual hardness of the rubber compound measured; E: Determine the shrinkage rate based on the amount of raw material injected: Determine the shrinkage rate based on the ratio of the raw material mass to the finished product mass; F: Determine the shrinkage rate according to the type of rubber: The shrinkage rates of different types of rubber are different. For example, the shrinkage rate of natural rubber is 1.2% to 2.0%. In a specific formula, the experience value of the shrinkage rate of natural rubber is 1.6% to 2.4%. The shrinkage rate of nitrile rubber is 1.8% to 2.2%, and that of silicone rubber is 3.2% to 3.4%. The shrinkage rate is determined according to the actual type of rubber used.

[0026] After the shrinkage rates of the above six aspects are determined, the total shrinkage rate is obtained by adding up the six shrinkage rates.

[0027] Next, the size of the space for injecting rubber into the mold needs to be determined based on the rubber shrinkage rate to design the shape and size of the mold. The specific process is as follows: Based on the required size of the rubber after cooling in the rubber vulcanized product, the relationship between the size of the rubber and the size of the space in the mold where the rubber is injected is calculated using the formula (1): K=(Dg-Dz) / Dz*100% (1) Wherein, K is the total shrinkage of the rubber to be vulcanized, Dg is the size of the space in the mold 12 into which the rubber is injected at room temperature, and Dz is the size of the rubber portion of the rubber vulcanized product at room temperature; Formula (2) can be derived: Dg=K*Dz+Dz (2) It can be seen from formula (2) that when the total shrinkage rate K and the size Dz of the rubber in the rubber vulcanized product are determined, the size Dg of the space for injecting rubber into the mold can be determined, thereby designing the shape and size of the mold that meets the requirements.

[0028] After the shape and size of the mold are designed, the mold and the components in the rubber vulcanized product are assembled into a closed space for injecting rubber, and then the molten rubber is injected into the closed space. After the rubber is cooled, the rubber vulcanized product is demoulded and taken out, so that the size of the produced rubber vulcanized product meets the design requirements. The assembly steps of the mold 11 include: S1. First install the split lower insert 9 into the lower mold 12, and then install the mandrel 10 onto the lower insert 9; S2. Sequentially place the petal-type jacket 5 and the partition 7 on the upper surface of the lower insert 9; S3. The petal-type petal mold 4 is closed; S4. Assemble the split-flap upper insert 8 and the mandrel 10; S5. Assemble the mold 11 and inject the rubber cartridge 3; S6. The rubber plug 2 and the upper mold 1 are sequentially injected to complete the mold installation.

[0029] The molten rubber is injected into the mold by opening a through injection hole on the injection cylinder 3 and the upper insert 8, injecting the molten rubber into the mold through the injection holes of the injection cylinder 3 and the upper insert 8, so that the molten rubber is injected into the gap between the core shaft 10 and the outer sleeve 5, thereby vulcanizing the core shaft 10 and the outer sleeve 5 into a whole with the rubber, and forming a product after cooling.

[0030] After the product is cooled and formed, the demoulding steps include: S1. Take out the upper mold 1, the injection plug 2 and the injection cylinder 3 respectively; S2. Pry and remove the middle mold 11; S3. Remove the petal-type petal mold 4; S4. Remove the petal-type upper insert 8; S5. Take out the product and the lower insert 9 in turn to obtain a rubber vulcanized product that meets the design requirements and complete demolding.

[0031] Obviously, without departing from the principles of the present invention, several improvements or modifications made should be considered as within the protection scope of the present invention.

Claims

1. A method for controlling the size of a rubber vulcanized product, characterized in that: First determine the size of the rubber vulcanized product in actual application, then determine the shrinkage rate of the rubber during the manufacturing process, and then set the size of the space for injecting rubber in the mold according to the shrinkage rate of the rubber, thereby determining the size of the mold for producing rubber vulcanized products, so as to produce rubber vulcanized products that meet the design size requirements.

2. A method for controlling the size of a rubber vulcanized product according to claim 1, characterized in that: The determination of rubber shrinkage during the manufacturing process includes the following 6 aspects: A: The shrinkage rate is determined according to the temperature during vulcanization; B: Determine the shrinkage rate based on the amount of sulfur used; C: Determine the shrinkage rate based on the glue content; D: Determine the shrinkage rate based on the hardness of the rubber; E: Determine the shrinkage rate based on the amount of raw material injected; F: Determine the shrinkage rate according to the type of rubber; After the shrinkage rates of the above six aspects are determined, the total shrinkage rate is obtained by adding up the six shrinkage rates.

3. A method for controlling the size of a rubber vulcanized product according to claim 2, characterized in that: Based on the required size of the rubber after cooling in the rubber vulcanized product, the relationship between the size of the rubber and the size of the space in the mold where the rubber is injected is calculated by the formula (1): K=(Dg-Dz) / Dz*100% (1) Wherein, K is the total shrinkage of the rubber to be vulcanized, Dg is the size of the space in the mold into which the rubber is injected at room temperature, and Dz is the size of the rubber portion of the rubber vulcanized product at room temperature; Formula (2) can be derived: Dg=K*Dz+Dz (2) From formula (2), it can be seen that when the total shrinkage rate K and the size Dz of the rubber in the rubber vulcanized product are determined, the size Dg of the space for injecting rubber into the mold can be determined, thereby designing the shape and size of the mold.

4. A method for controlling the size of a rubber vulcanized product according to claim 3, characterized in that: After the shape and size of the mold are designed, the mold and the components in the rubber vulcanized product are assembled into a closed space for injecting rubber, and then molten rubber is injected into the closed space. After the rubber cools down, the rubber vulcanized product is demoulded and taken out, so that the size of the produced rubber vulcanized product meets the design requirements.

5. A method for controlling the size of a rubber vulcanized product according to claim 4, characterized in that: The rubber vulcanized product includes a core shaft, a rubber layer and a jacket. The mold for producing the rubber vulcanized product includes a flap mold, a partition, an upper insert, a lower insert, an upper mold, a rubber injection cylinder, a middle mold and a lower mold; the core shaft, the jacket, the upper insert and the lower insert are together surrounded to form a closed space for injecting rubber.

6. A method for controlling the size of a rubber vulcanized product according to claim 5, characterized in that: Telescopic grooves are provided on the lower surface of the upper insert and the upper surface of the lower insert, and the telescopic grooves on the surfaces of the upper insert and the lower insert are respectively recessed toward the interior of the upper insert and the lower insert; and the telescopic grooves on the surfaces of the upper insert and the lower insert are arranged in a closed space for injecting rubber surrounded by the core shaft, the outer sleeve, the upper insert and the lower insert. When the molten rubber is injected into the closed space, bulges are formed at both ends of each petal-type rubber layer in the vertical direction. When the molten rubber is cooled and the rubber layer shrinks, the bulges formed at both ends in the vertical direction gradually become flat.

7. A method for controlling the size of a rubber vulcanized product according to claim 6, characterized in that: The middle mold is arranged between the upper mold and the lower mold, and a glue injection cylinder is arranged between the upper mold and the middle mold, a groove is opened at the bottom of the glue injection cylinder, and an upper insert is arranged in the groove; a through mounting hole is opened in the middle mold, and a petal mold and a partition are arranged in the mounting hole of the middle mold, the petal mold is arranged on the outside of the outer sleeve in the circumferential direction, and the partition is arranged on the outside of the core shaft in the circumferential direction, and a circular groove is opened in the lower mold, and a lower insert is arranged in the circular groove.

8. The method for controlling the size of a rubber vulcanized product according to claim 7, characterized in that: First, assemble the mold, enclose a closed space for injecting rubber in the mold, inject molten rubber into the closed space of the mold, and demould the rubber vulcanized product after the rubber cools down. The assembly steps of the mold include: S1. First install the split lower insert into the lower mold, and then install the mandrel onto the lower insert; S2. Sequentially place the petal-type jacket and partition on the upper surface of the lower panel; S3. Close the petal mold; S4. Assemble the split upper insert and the mandrel; S5. Assemble the middle mold and inject the rubber cylinder; S6. Place the rubber plug and the upper mold in sequence to complete the mold installation.

9. A method for controlling the size of a rubber vulcanized product according to claim 8, characterized in that: The molten rubber is injected into the closed space of the mold by opening a through injection hole on the injection cylinder and the upper insert, injecting the molten rubber into the mold through the injection hole of the injection cylinder and the upper insert, so that the molten rubber is injected into the gap between the core shaft and the outer sleeve, thereby vulcanizing the core shaft and the outer sleeve into a whole with the rubber, and forming a rubber vulcanized product with dimensions meeting the design requirements after cooling.

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