Rubber handle sheath forming equipment and forming process thereof

Abstract

The invention discloses rubber handle sheath forming equipment and a forming process thereof, and the forming process comprises the following steps: mixing polyurethane, polyacrylonitrile, a foaming agent and the like to obtain an inner-layer material, and injecting the inner-layer material into an inner-layer injection charging barrel; injecting an outer layer material into an outer layer injection charging barrel; injecting the outer-layer material into the mold to form a wear-resistant layer, and then injecting the inner-layer material to fill the mold; the inner-layer material is foamed, and polyacrylonitrile is separated out to form a reticular fiber structure; and cooling and demolding to obtain the rubber handle sheath. A co-injection foaming technology is used, an inner-layer foaming material with polyurethane as a main component and an outer-layer rubber material with a hard texture are simultaneously or continuously injected into a handle sheath mold, and the integrated handle sheath with a hard wear-resistant outer layer and a soft foaming inner layer is prepared. Wherein the wear-resistant layer obviously improves the wear resistance of the handle sheath, and the foaming inner layer provides soft holding feeling and good elastic recovery, so that the use comfort is improved.

Description

Technical Field

[0001] The invention relates to the technical field of injection molding, in particular to foaming molding of plastic state materials, and in particular to a rubber handlebar sheath molding device and a molding process thereof. Background Art

[0002] Rubber handlebar covers are widely used in many industries. In the field of sporting goods, they are commonly found in fitness equipment such as treadmills, walking machines and comprehensive training machines, providing users with a comfortable grip on the handlebars and effectively reducing hand fatigue. In the vehicle accessories industry, whether it is a bicycle, motorcycle or car, rubber handlebar covers can provide a high-quality grip experience and anti-slip performance, thereby improving driving comfort and safety.

[0003] Rubber handle guards are tubular protective structures made of rubber and are usually used on the handles of various equipment and tools to provide users with a more comfortable grip and enhanced anti-slip performance. Some handle guards use a multi-layer design, including a buffer layer and a wear-resistant layer, to further enhance durability and protection. In addition, there is also an integrated molding structure design, which makes the guard more stable and durable.

[0004] However, the current molding process of rubber handlebar covers mainly relies on single injection molding or foaming technology, which has certain limitations in production efficiency, product quality and functionality. Especially in the manufacturing process of multi-layer structures, the method of layered preparation and then bonding is often adopted, but the interlayer bonding strength of the cover prepared by this method is insufficient, and it is easy to delaminate and crack.

[0005] Therefore, it is necessary to provide a rubber handlebar sheath molding device and a molding process thereof to solve the above-mentioned technical problems. Summary of the invention

[0006] The invention overcomes the shortcomings of the prior art and provides a rubber handlebar sheath molding device and a molding process thereof.

[0007] To achieve the above object, the technical solution adopted by the present invention is: a molding process of a rubber handlebar sheath, comprising the following steps: S1. 80 parts of polyurethane, 0-20 parts of polyacrylonitrile, 0-5 parts of foaming agent, 0-1 part of stabilizer, 0-2 parts of lubricant and 0-1 part of antioxidant are uniformly blended by weight to obtain an inner layer material, and the inner layer injection material is added into the inner layer injection barrel; S2, 100 parts of outer layer rubber material, 0-2 parts of vulcanizing agent, 0-2 parts of accelerator, 0-3 parts of activator, 0-5 parts of reinforcing injection agent, 0-2 parts of plasticizer and 0-1 part of antioxidant are uniformly blended by weight to obtain an outer layer injection material, and the outer layer material is added into the outer layer injection barrel; S3, injecting the outer layer material into the handle cover mold, the outer layer material adheres to the wall of the handle cover mold cavity to form a wear-resistant layer, and the injection degree is set to 30-40%; S4, injecting the inner layer material into the center of the handle cover mold along with the outer layer material until the handle cover mold is 100% filled, the inner layer material is depressurized and foamed after entering the handle cover mold, and polyacrylonitrile is precipitated from the inner layer material along with the foaming gas and migrates to the contact boundary between the inner layer material and the outer layer material, forming a mesh fiber structure spanning the inner layer material and the outer layer material; S5. Lower the temperature of the handlebar cover mold to room temperature, keep it for 5 to 20 minutes without pressure maintenance, and cool and demould the handlebar cover to obtain a rubber handlebar cover.

[0008] In a preferred embodiment of the present invention, in said S1, the temperature of the inner layer material blending and the inner layer injection barrel is 280-350°C and the pressure is 8-20MPa.

[0009] In a preferred embodiment of the present invention, the outer layer rubber material is one of vulcanized rubber, styrene-butadiene rubber or chloroprene rubber.

[0010] In a preferred embodiment of the present invention, in S4, the foaming process of the inner layer material is controlled by using a staged foaming technology, comprising the following steps: S41, the initial temperature of the handle cover mold is controlled at 80-100°C, and the pressure is controlled at 10-20MPa; S42, initial foaming stage: after the injection of the inner layer material begins, the temperature increases by 5°C every 5 seconds, and the pressure decreases by 1MPa every 5 seconds; S43, the generation and stabilization stage of foaming gas: When the temperature in the handlebar cover mold is 110-120°C, maintain the temperature and pressure for 30-60 seconds; When the temperature in the handlebar cover mold is 130-140°C, maintain the temperature and pressure for 30-60 seconds; When the temperature in the handlebar cover mold is 150-160°C, maintain the temperature and pressure for 30-60 seconds; S44, inner layer material foam curing: The temperature of the handlebar sheath mold is reduced to 80-100°C, and the pressure is reduced to 0.5-1.5MPa for 2-5min.

[0011] In a preferred embodiment of the present invention, in S42 and S43, the handlebar sheath mold is vibrated: the vibration frequency is 15-30 Hz, the vibration amplitude is 60-100 um, and the vibration is cyclically vibrated in multiple directions for 2-5 seconds.

[0012] In a preferred embodiment of the present invention, in said S4, the injection rate of the inner layer material is 2 to 3 times the injection rate of the outer layer material.

[0013] A rubber handlebar sheath molding device, based on any one of the above-mentioned rubber handlebar sheath molding processes, comprises: an injection system, a handlebar sheath mold, and a control system for controlling the operation of the injection system and the handlebar sheath mold; The injection system comprises: a plurality of injection barrels, a discharge pipe arranged at one side of the injection barrel, and a nozzle arranged at the other end of the discharge pipe; The discharge pipe is a multi-outlet structure, each of which is connected to a plurality of nozzles; The nozzle comprises: a discharge port, an inner material flow channel and an outer material flow channel connected to a discharge pipe; The discharge port is connected to the handle cover mold to inject material therein; The inner layer material flow channel is arranged at the central part of the outer layer material flow channel; The handlebar cover mold comprises: an upper mold and a lower mold combined into a tubular structure cavity, which are used for molding the rubber handlebar cover; The control system includes: a temperature control module, a pressure control module, an injection barrel control module and an automation control module; The temperature control module includes: a plurality of temperature monitoring units and a temperature regulating unit; the plurality of temperature monitoring units are used to monitor the temperature of the injection barrel and the handlebar cover mold respectively, and the plurality of temperature regulating units are used to regulate the temperature of the injection barrel and the handlebar cover mold respectively; The pressure control module includes: a plurality of pressure monitoring units and a pressure regulating unit; the plurality of pressure monitoring units are used to monitor the pressure of the injection barrel and the handlebar cover mold respectively, and the plurality of pressure regulating units are used to regulate the pressure of the injection barrel and the handlebar cover mold respectively; The injection barrel control module is used to control the injection rates of a plurality of injection barrels; The automation control module is used to integrate and control the operation of the injection system, the handle cover mold and the control system, and accurately execute the molding process steps of the rubber handle cover.

[0014] In a preferred embodiment of the present invention, the plurality of injection barrels include: an inner injection barrel and an outer injection barrel that are independent of each other.

[0015] In a preferred embodiment of the present invention, the automation control module is provided with a staged foaming mechanism, including: The initial temperature of the handlebar cover mold is controlled at 80-100°C, and the pressure is controlled at 10-20MPa; In the initial foaming stage after the injection of the inner layer material begins: the temperature increases by 5°C every 5s, and the pressure decreases by 1MPa every 5s; Foaming gas generation and stabilization stage: When the temperature in the handlebar cover mold is 110-120° C., the temperature and pressure are maintained for 30-60 seconds; When the temperature in the handlebar cover mold is 130-140° C., the temperature and pressure are maintained for 30-60 seconds; When the temperature in the handlebar cover mold is 150-160° C., the temperature and pressure are maintained for 30-60 seconds; Inner material foam curing: The temperature of the handlebar sheath mold is reduced to 80-100° C., and the pressure is reduced to 0.5-1.5 MPa for 2-5 minutes.

[0016] In a preferred embodiment of the present invention, the control system further comprises a vibration module, and the vibration module comprises: a plurality of vibration units; the plurality of vibration units are evenly distributed on the outer surface of the handlebar cover mold.

[0017] The present invention solves the defects existing in the background technology and has the following beneficial effects: (1) The present invention provides a molding process for a rubber handlebar cover. By using the co-injection foaming technology, an inner foaming material with polyurethane as the main component and an outer rubber material with a harder texture are simultaneously or continuously injected into the handlebar cover mold to prepare an integrated handlebar cover with a hard wear-resistant outer layer and a soft foamed inner layer. The wear-resistant layer significantly improves the wear resistance of the handlebar cover, while the foamed inner layer provides a soft grip and good elastic recovery, thereby increasing the comfort of use. Compared with the prior art, the present invention prepares the rubber handlebar cover by integral molding, which not only significantly improves the production efficiency, but also effectively solves the problems of poor interface connection, delamination and cracking that may occur during the layered preparation and bonding process.

[0018] (2) The present invention adds polyacrylonitrile to the foaming inner layer material. The melting point of polyacrylonitrile is much higher than the foaming temperature of polyurethane. When the inner layer material enters the handlebar cover mold, the pressure decreases, the polyurethane begins to foam, and as the temperature increases, the viscosity of the polyurethane matrix decreases. Due to the thermal stability of polyacrylonitrile, an independent phase is formed in the polyurethane matrix. Polyacrylonitrile will precipitate from the polyurethane with the movement of the foaming gas. In addition, because the temperature of polyacrylonitrile is higher than the melting point before injection, the temperature decreases after entering the handlebar cover mold. The precipitation process cooperates with the curing process after cooling. Polyacrylonitrile achieves the goal of spanning the two interfaces of the inner layer material and the outer layer material, and forms a network-like fiber morphology between the two interfaces, thereby increasing the connection between the inner and outer layers and further reducing the problems of stratification and cracking.

[0019] (3) During the injection process of the present invention, the outer layer material is first injected to adhere to the wall of the mold cavity of the handlebar cover mold to form a wear-resistant layer. After the injection degree reaches 30-40%, the inner layer material and the outer layer material are injected simultaneously, and the inner layer material is in the center of the outer layer material, and the injection rate of the inner layer material is 2-3 times that of the outer layer material, ensuring that the inner layer material is always wrapped by the outer layer material during the injection and subsequent foaming process, effectively preventing the inner layer material from being exposed, significantly improving the molding efficiency of the rubber handlebar cover, and effectively improving the product yield.

[0020] (4) The present invention proposes a staged foaming technology. After the inner layer material starts to foam, the duration of the foaming process is effectively extended by controlling a series of temperature, pressure and pressure holding time. This provides sufficient precipitation time for polyacrylonitrile in the polyurethane matrix, ensuring that more polyacrylonitrile can be smoothly precipitated to the contact boundary between the inner layer material and the outer layer material. This technical improvement significantly increases the connection anchor points between the inner layer material and the outer layer material, thereby greatly reducing the delamination and cracking problems that may occur during the use of the product, and improving the stability and durability of the overall structure.

[0021] (5) The present invention effectively reduces the viscosity of the injection material melt and significantly improves its fluidity by introducing vibration-assisted means during the foaming process of the inner layer material and combining it with the co-injection foaming technology. This innovative method helps to achieve a more uniform melt distribution and better mold filling performance during the co-injection foaming molding process. At the same time, this method can also significantly reduce common defects in the injection molding process, such as weld marks, dents and warping, thereby greatly improving the quality of the finished rubber handlebar cover.

[0022] (6) In the foaming process of the inner layer material, the present invention uses multi-directional sequential cyclic vibration combined with staged foaming technology. Through the multi-directional vibration effect, the foaming gas molecules can be more evenly dispersed in the polyurethane matrix, thereby generating a smaller and more evenly distributed foam cell structure. This improvement significantly increases the amount and uniformity of polyacrylonitrile precipitated in the inner layer material, thereby promoting the migration of polyacrylonitrile to the contact boundary between the inner layer material and the outer layer material. In addition, multi-directional vibration also helps the precipitated polyacrylonitrile fibers change direction and achieve cross-connection, thereby constructing a complex mesh fiber structure spanning the inner and outer layer materials. This mesh fiber structure not only enhances the structural integrity of the handlebar cover, but also significantly improves its mechanical properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art are briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative work. Figure 1 The present invention is a flow chart of a molding process of a rubber handlebar sheath according to a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited to the specific embodiments disclosed below.

[0026] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the scope of protection of the present application.

[0027] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood by specific circumstances.

[0028] like Figure 1 As shown, the present invention provides a molding process for a rubber handlebar sheath, comprising the following steps: S1. 80 parts of polyurethane, 0-20 parts of polyacrylonitrile, 0-5 parts of foaming agent, 0-1 part of stabilizer, 0-2 parts of lubricant and 0-1 part of antioxidant are uniformly blended by weight to obtain the inner layer material, and the inner layer injection material is added into the inner layer injection barrel.

[0029] S2. Evenly blend 100 parts of outer layer rubber material, 0-2 parts of vulcanizer, 0-2 parts of accelerator, 0-3 parts of activator, 0-5 parts of reinforcing injection agent, 0-2 parts of plasticizer and 0-1 part of antioxidant by weight to obtain outer layer injection material, and add the outer layer material into the outer layer injection barrel.

[0030] S3. Inject the outer layer material into the handlebar cover mold, and the outer layer material adheres to the wall of the handlebar cover mold cavity to form a wear-resistant layer. The injection degree is set to 30-40%.

[0031] S4. The inner layer material is injected into the center of the handle cover mold along with the outer layer material until the handle cover mold is 100% filled. After the inner layer material enters the handle cover mold, it is depressurized and foamed. Polyacrylonitrile is precipitated from the inner layer material along with the foaming gas and migrates to the contact boundary between the inner layer material and the outer layer material, forming a mesh fiber structure spanning the inner layer material and the outer layer material.

[0032] S5. Lower the temperature of the handlebar cover mold to room temperature, keep it for 5 to 20 minutes without pressure maintenance, and cool and demould the handlebar cover to obtain a rubber handlebar cover.

[0033] The present invention provides a molding process for a rubber handlebar cover. By using the co-injection foaming technology, an inner foaming material with polyurethane as the main component and an outer rubber material with a harder texture are simultaneously or continuously injected into a handlebar cover mold to prepare an integrated handlebar cover having a hard wear-resistant outer layer and a soft foamed inner layer. The wear-resistant layer significantly improves the wear resistance of the handlebar cover, and the foamed inner layer provides a soft grip and good elastic recovery, thereby increasing the comfort of use. Compared with the prior art, the present invention prepares the rubber handlebar cover by integral molding, which not only significantly improves the production efficiency, but also effectively solves the problems of poor interface connection, delamination and cracking that may occur during the layered preparation and bonding process.

[0034] In step S1, the temperature of the inner layer material blending and the inner layer injection barrel is 280-350°C and the pressure is 8-20MPa. The melting point of the polyurethane in the inner layer material is about 180°C, and the melting point of polyacrylonitrile is about 300°C. The temperature and pressure settings of the blender and the inner layer injection barrel can ensure that the polyurethane and polyacrylonitrile therein are in a molten state to ensure the blending effect.

[0035] In step S1, polyurethane is preferably Desmodur® series material of Bayer Company; polyacrylonitrile is preferably powdered Zytel® series material of DuPont Company. In this step, polyurethane particles and polyacrylonitrile powder are added to a blender in proportion for melt mixing, and after mixing for 2 to 5 minutes, the remaining functional additives such as foaming agent, stabilizer, lubricant and antioxidant in the blender are added, and the blending is continued for 5 to 10 minutes to form the inner layer material.

[0036] It is worth noting that the foaming agent is added in the final stage of mixing, and after adding, mixing is continued for 5 to 20 seconds and then immediately transferred to the inner injection barrel.

[0037] The foaming agent in this embodiment uses azobisisobutyronitrile or sodium bicarbonate to form a foam structure in the inner layer material, thereby increasing the elasticity and cushioning performance of the inner layer material.

[0038] The stabilizer in this embodiment uses calcium stearate or zinc stearate to prevent the inner layer material from being degraded during processing or use.

[0039] The lubricant in this embodiment uses stearic acid or paraffin to reduce the friction coefficient of the inner layer material and improve the processing performance.

[0040] The antioxidant in this embodiment uses 2,6-di-tert-butyl-4-methylphenol or butylated hydroxyanisole to extend the service life of the inner layer material and prevent oxidation and deterioration.

[0041] The outer rubber material in this embodiment is one of vulcanized rubber, styrene-butadiene rubber or chloroprene rubber, and styrene-butadiene rubber is preferably used as the base material of the wear-resistant layer, which provides good wear resistance and cost-effectiveness.

[0042] The accelerator in this embodiment uses one of tetramethylthiuram diphenyl disulfide and dimethylthiuram diphenyl disulfide to accelerate the vulcanization process.

[0043] The activator in this embodiment uses zinc oxide or stearic acid to increase the activity of the vulcanizing agent.

[0044] The reinforcing injection agent in this embodiment uses carbon black or a silane coupling agent, preferably carbon black, to improve the strength and wear resistance of the rubber.

[0045] The plasticizer in this embodiment uses dibutyl phthalate or diisobutyl phthalate to increase the softness and plasticity of the outer layer material.

[0046] The present invention realizes the synchronous preparation of the inner layer foaming material and the outer layer wear-resistant material by adopting two independent injection barrels, improves the preparation efficiency, and ensures the independence and stability of the two materials during the preparation process.

[0047] In step S3, the injection speed and time of the outer layer material are controlled according to the volume of the handlebar cover mold, so that the filling degree of the outer layer material in the handlebar cover mold is controlled within 30-40%. A stable outer layer material layer is first constructed in the handlebar cover mold, which can provide a solid foundation for the subsequent injection of the inner layer material and help maintain the structural integrity of the handlebar cover.

[0048] During the injection process of step S4, the inner layer material is precisely injected into the center of the outer layer material, thereby pushing the outer layer material to move orderly toward the inside of the handle cover mold. At the same time, the synchronous injection operation of the outer layer material is also steadily carried out. When the outer layer material moves toward the inside of the handle cover mold under the push of the inner layer material, the newly injected outer layer material tightly covers the surface of the inner layer material, thereby ensuring the structural integrity and sealing of the handle cover, and effectively preventing the leakage of the inner layer material.

[0049] The present invention adds polyacrylonitrile to the foaming inner layer material. The melting point of polyacrylonitrile is much higher than the foaming temperature of polyurethane. When the inner layer material enters the handlebar cover mold, the pressure decreases, the polyurethane starts to foam, and as the temperature increases, the viscosity of the polyurethane matrix decreases. Due to the thermal stability of polyacrylonitrile, an independent phase is formed in the polyurethane matrix. The polyacrylonitrile will precipitate from the polyurethane with the movement of the foaming gas. Moreover, because the temperature of the polyacrylonitrile is higher than the melting point before injection, the temperature decreases after entering the handlebar cover mold. The precipitation process cooperates with the curing process after the temperature decreases. The polyacrylonitrile achieves the goal of spanning the two interfaces of the inner layer material and the outer layer material, and forms a network-like fiber morphology between the two interfaces, thereby increasing the connection between the inner and outer layers and further reducing the problems of stratification and cracking.

[0050] In step S4, the foaming process of the inner layer material is controlled by using a staged foaming technology, including the following steps: S41, the initial temperature of the handle cover mold is controlled at 80-100°C, and the pressure is controlled at 10-20MPa; S42, initial foaming stage: after the injection of the inner layer material begins, the temperature increases by 5°C every 5 seconds and the pressure decreases by 1MPa every 5 seconds; the combination of increased temperature and reduced pressure helps to start the decomposition of the foaming agent and generate gas, while the reduced pressure helps the gas diffuse in the material to form foam.

[0051] S43, the generation and stabilization stage of foaming gas: When the temperature in the handlebar cover mold is 110-120°C, maintain the temperature and pressure for 30-60 seconds; When the temperature in the handlebar cover mold is 130-140°C, maintain the temperature and pressure for 30-60 seconds; When the temperature in the handlebar cover mold is 150-160°C, maintain the temperature and pressure for 30-60 seconds; Slow temperature and pressure adjustment, as well as the pressure holding stage after adjustment, can delay and control the foaming process.

[0052] S44, inner layer material foam curing: The temperature of the handlebar cover mold is reduced to 80-100℃, and the pressure is reduced to 0.5-1.5MPa for 2-5min. After this step of process, the inner layer material has been fully foamed, and the outer layer material fits the handlebar cover mold tightly. To ensure that the product meets the use requirements, the inner wall of the handlebar cover mold is accurately set with various patterns or dents according to actual needs.

[0053] The present invention proposes a staged foaming technology. After the inner layer material starts to foam, the duration of the foaming process is effectively extended through a series of temperature, pressure and pressure holding time controls. This provides sufficient precipitation time for polyacrylonitrile in the polyurethane matrix, ensuring that more polyacrylonitrile can be smoothly precipitated to the contact boundary between the inner layer material and the outer layer material. This technical improvement significantly increases the connection anchor points between the inner layer material and the outer layer material, thereby greatly reducing the delamination and cracking problems that may occur during the use of the product, and improving the stability and durability of the overall structure.

[0054] In steps S42 and S43, the handlebar sheath mold is vibrated: the vibration frequency is 15-30 Hz, the vibration amplitude is 60-100 um, and the vibration is cyclically vibrated in multiple directions for 2-5 seconds.

[0055] The vibration direction in this embodiment is clockwise along the vibration points on the cross section of the handle cover mold, and the vibration points are evenly distributed on the surface of the handle cover mold. Through multi-directional cyclic vibration, it can be ensured that every corner and complex geometric features of the mold can be fully filled with material, reducing the problem of dead corners and incomplete filling.

[0056] The present invention effectively reduces the viscosity of the injection material melt by introducing vibration assistance during the foaming process of the inner layer material and combines it with the co-injection foaming technology, thereby significantly improving its fluidity. This innovative method helps to achieve a more uniform melt distribution and better mold filling performance during the co-injection foaming molding process. At the same time, the method can also significantly reduce common defects in the injection molding process, such as weld marks, dents and warping, thereby greatly improving the quality of the finished rubber handle cover.

[0057] In the foaming process of the inner layer material, the present invention uses multi-directional sequential cyclic vibration combined with staged foaming technology. Through the multi-directional vibration effect, the foaming gas molecules can be more evenly dispersed in the polyurethane matrix, thereby generating a smaller and more evenly distributed foam cell structure. This improvement significantly increases the amount and uniformity of polyacrylonitrile precipitated in the inner layer material, thereby promoting the migration of polyacrylonitrile to the contact boundary between the inner layer material and the outer layer material. In addition, multi-directional vibration also helps the precipitated polyacrylonitrile fibers change direction and achieve cross-connection, thereby constructing a complex mesh fiber structure spanning the inner and outer layer materials. This mesh fiber structure not only enhances the structural integrity of the handlebar cover, but also significantly improves its mechanical properties.

[0058] In step S4, the injection rate of the inner layer material is 2 to 3 times the injection rate of the outer layer material.

[0059] During the injection process, the present invention first injects the outer layer material to adhere to the wall of the mold cavity of the handlebar cover mold to form a wear-resistant layer. After the injection degree reaches 30-40%, the inner layer material and the outer layer material are injected synchronously, and the inner layer material is in the center of the outer layer material, and the injection rate of the inner layer material is 2-3 times that of the outer layer material, ensuring that the inner layer material is always wrapped by the outer layer material during the injection and subsequent foaming process, effectively preventing the inner layer material from being exposed, significantly improving the molding efficiency of the rubber handlebar cover, and effectively improving the product yield.

[0060] The present invention also provides a rubber handlebar sheath molding device, comprising: an injection system, a handlebar sheath mold, and a control system for controlling the operation of the injection system and the handlebar sheath mold.

[0061] The injection system in this embodiment includes: a plurality of injection barrels, a discharge pipe arranged on one side of the injection barrel, and a nozzle arranged at the other end of the discharge pipe; the discharge pipe is a multi-outlet end structure, which is respectively connected to a plurality of nozzles, that is, a discharge pipe connected to an injection barrel can be connected to a plurality of nozzles, and a plurality of nozzles correspond to processing a plurality of handle cover molds, thereby realizing simultaneous processing of multiple products.

[0062] The nozzle in this embodiment includes: a discharge port, an inner material flow channel and an outer material flow channel connected to a discharge pipe; the discharge port is connected to the handle cover mold to inject material into it; the inner material flow channel is arranged at the center of the outer material flow channel. It is worth noting that the inner layer flow channel and the outer layer flow channel are two annular flow channels arranged with the same center, and the inner layer flow channel is arranged in the middle of the outer layer flow channel.

[0063] The handlebar cover mold in this embodiment includes: an upper mold and a lower mold combined into a tubular structure cavity, which are used for molding the rubber handlebar cover.

[0064] The control system in this embodiment includes: a temperature control module, a pressure control module, an injection barrel control module and an automation control module; the temperature control module includes: a number of temperature monitoring units and a temperature regulating unit; the number of temperature monitoring units are used to monitor the temperature of the injection barrel and the handle cover mold, and the number of temperature regulating units are used to adjust the temperature of the injection barrel and the handle cover mold; the pressure control module includes: a number of pressure monitoring units and a pressure regulating unit; the number of pressure monitoring units are used to monitor the pressure of the injection barrel and the handle cover mold, and the number of pressure regulating units are used to adjust the pressure of the injection barrel and the handle cover mold; the injection barrel control module is used to control the injection rate of a number of injection barrels, which is achieved through valve control.

[0065] The automation control module in this embodiment is used to integrate and control the operation of the injection system, the handle cover mold and the control system, and accurately execute the molding process steps of the rubber handle cover.

[0066] The plurality of injection barrels in this embodiment include: an inner injection barrel and an outer injection barrel that are independent of each other.

[0067] The automation control module in this embodiment is provided with a staged foaming mechanism, including: The initial temperature of the handlebar cover mold is controlled at 80-100°C, and the pressure is controlled at 10-20MPa; In the initial foaming stage after the injection of the inner layer material begins: the temperature increases by 5°C every 5s, and the pressure decreases by 1MPa every 5s; Foaming gas generation and stabilization stage: When the temperature in the handlebar cover mold is 110-120°C, maintain the temperature and pressure for 30-60 seconds; When the temperature in the handlebar cover mold is 130-140°C, maintain the temperature and pressure for 30-60 seconds; When the temperature in the handlebar cover mold is 150-160°C, maintain the temperature and pressure for 30-60 seconds; Inner material foam curing: The temperature of the handlebar sheath mold is reduced to 80-100°C, and the pressure is reduced to 0.5-1.5MPa for 2-5min.

[0068] The control system in this embodiment further includes a vibration module, which includes: a plurality of vibration units, preferably an electric vibrator; and the plurality of vibration units are evenly distributed on the outer surface of the handlebar cover mold.

[0069] The present invention provides a rubber handle cover molding device, which is connected to multiple nozzles through a discharge pipe with multiple outlet ends, so as to realize the synchronous processing of multiple handle cover molds. This design enables the device to process multiple products at the same time, significantly improves production efficiency, and effectively shortens the production cycle. In addition, the device is also equipped with an automatic control module, which can accurately execute the molding process steps of the rubber handle cover, ensuring that each cover is accurately produced according to preset parameters, thereby improving the stability and consistency of the product.

[0070] Example 1: A rubber handle cover sample is prepared based on the above-mentioned molding process of the rubber handle cover.

[0071] Step 1: 80 parts of polyurethane particles, 15 parts of polyacrylonitrile powder, 3 parts of azobisisobutyronitrile, 1 part of calcium stearate, 1 part of stearic acid and 1 part of 2,6-di-tert-butyl-4-methylphenol solvent are uniformly blended by weight to obtain an inner layer material, and the inner layer injection material is added to the inner layer injection barrel, wherein the temperature of the blender and the inner layer injection barrel is set to 320° C. and the pressure is 18 MPa.

[0072] 100 parts of styrene-butadiene rubber particles, 1 part of vulcanizing agent, 1 part of tetramethylthiuram diphenyl disulfide, 2 parts of zinc oxide, 3 parts of carbon black, 1 part of dibutyl phthalate and 1 part of 2,6-di-tert-butyl-4-methylphenol solvent are uniformly blended by weight to obtain an outer layer injection material, and the outer layer material is added to an outer layer injection barrel, wherein the temperature of the blender and the outer layer injection barrel is set to 180 degrees Celsius and the pressure is 10 MPa.

[0073] Step 2: The handle cover mold is first preheated to 90°C and the internal pressure is controlled at 10MPa.

[0074] Step three, inject the outer layer material into the handle cover mold. When the filling degree of the outer layer material in the handle cover mold reaches 30%, start to inject the inner layer material into the handle cover mold along with the outer layer material. The injection speed of the inner layer material is 2.5 times the injection rate of the outer layer material. The inner layer material is injected earlier than the outer layer material until the handle cover mold is 100% filled. After the inner layer material enters the handle cover mold, it is depressurized and foamed.

[0075] During the foaming process of the inner layer material, the generation and stabilization stage of the foaming gas: When the temperature in the handlebar cover mold is 110°C, maintain the temperature and pressure for 45 seconds; When the temperature in the handlebar cover mold is 130°C, maintain the temperature and pressure for 45 seconds; When the temperature in the handlebar cover mold is 150°C, maintain the temperature and pressure for 45 seconds; In this step, the handlebar cover mold is vibrated: the vibration frequency is 20Hz, the vibration amplitude is 80um, and the vibration is cyclically cyclically vibrated in multiple directions, and the direction is changed every 5s.

[0076] Step 4: After the inner layer material is foamed, the temperature of the handlebar cover mold is lowered to 80°C and the pressure is 1MPa for 3 minutes to solidify the foam of the inner layer material.

[0077] Step 5: Lower the temperature of the handlebar cover mold to room temperature without pressure maintenance and keep it for 15 minutes. Finally, cool and demould the handlebar cover to obtain the rubber handlebar cover.

[0078] Example 2: A rubber handlebar cover is prepared based on Example 1, except that 5 parts of polyacrylonitrile powder are added to the inner layer material.

[0079] Example 3, a rubber handlebar cover is prepared based on Example 1, except that no polyacrylonitrile powder is added to the inner layer material.

[0080] Example 4, the preparation of the rubber handle cover is based on Example 1, the difference lies in the control of the foaming process of the inner layer material: the temperature of the handle cover mold is 150°C, and the pressure is 3MPa. After the injection of the inner layer material begins, the pressure in the handle cover mold is reduced to 1MPa after 10s, and the temperature and pressure are kept unchanged until the inner layer foam material is solidified.

[0081] Example 5: A rubber handlebar cover is prepared based on Example 1, except that the temperature and pressure of the handlebar cover mold are always controlled at 80° C. and 1 MPa.

[0082] Example 6, the rubber handle cover is prepared based on Example 1, the difference lies in the foaming stage of the inner layer material: after the injection of the inner layer material begins, the temperature increases by 5°C every 5 seconds, and the pressure decreases by 1 MPa every 5 seconds; there is no temperature and pressure holding stage in the middle, until the temperature rises to 150°C, then the temperature increase and pressure reduction are stopped.

[0083] Example 7, a rubber handlebar cover is prepared based on Example 1, except that during the foaming process of the inner layer material, no vibration is applied to the handlebar cover mold.

[0084] Example 8, the rubber handle cover is prepared based on Example 1, the difference is that the handle cover mold is vibrated: the vibration frequency is 45 Hz, the vibration amplitude is 120 um, and the vibration is cyclically performed in multiple directions in sequence, and the direction is changed every 10 seconds.

[0085] Example 9, the rubber handle cover is prepared based on Example 1, except that the handle cover mold is vibrated: the vibration frequency is 20 Hz, the vibration amplitude is 80 um, and a vibration unit is used to perform intermittent vibration for 5 seconds / time, and the vibration is performed in the vertical injection direction.

[0086] The rubber handlebar sheath prepared in the above embodiment was subjected to a peeling test and a tensile test, wherein the peeling test was conducted in accordance with the GB / T 2791-1995 standard, and the tensile test was conducted in accordance with the GB / T 528-1992 standard. The test results are shown in Table 1.

[0087] Table 1. Rubber handle guard performance test results

[0088] Based on the content of Table 1, it can be concluded that the rubber handlebar sheaths prepared in Examples 1 and 2 performed well in both the peeling test and the tensile test. Example 2 performed poorly in the peeling strength because less polyacrylonitrile powder was added to the inner layer material, resulting in less connection between the inner layer material and the outer layer material of the handlebar sheath, and the network-like fibers formed were sparse. In Example 3, because no polyacrylonitrile powder was added, the connection between the inner layer material and the outer layer material relied on its own viscosity and curing, and the rubber handlebar sheath prepared therefrom was prone to stratification and cracking.

[0089] The initial pressure of Example 4 is relatively low, and it is reduced to 1 MPa within 10 seconds, resulting in the foaming process of the inner layer material being too fast. Polyacrylonitrile does not have sufficient time to precipitate and transfer to the contact boundary between the inner layer material and the outer layer material, and a sufficient connection cannot be formed. In Example 5, the temperature and pressure remain unchanged when the inner layer material is injected. The constant preparation conditions are not conducive to the decomposition of the foaming agent and the diffusion of the gas, resulting in insufficient foaming and insufficient strength. In Example 6, there is no staged pressure maintenance during the generation and stabilization of the foaming gas. The temperature is directly increased by 5°C every 5 seconds, and the pressure is reduced by 1 MPa every 5 seconds. There is no stage of maintaining the temperature and pressure until the temperature rises to 150°C, and the temperature increase and pressure reduction are stopped. The rapid temperature and pressure changes may cause the foaming process to be unstable, polyacrylonitrile to precipitate and migrate insufficiently, and affect the bonding between the inner and outer layer materials.

[0090] In Example 7, there is no auxiliary vibration during the foaming process, the amount and uniformity of polyacrylonitrile precipitation in the inner layer material are insufficient, and the precipitated polyacrylonitrile fibers are not cross-connected much, so that the mesh fiber structure constructed across the inner and outer layer materials is not complex enough, resulting in slightly poor peel strength performance. Although Example 8 used vibration assistance during the foaming process, the vibration frequency of 45Hz and the vibration amplitude of 120um were too high, resulting in uneven material filling and excessive dispersion, affecting the internal structure and performance of the material. In addition, the vibration that changes direction every 10 seconds results in a small distribution of fibers in different directions, and the mesh fiber structure is not complex enough, which affects the peel strength and tensile properties. Example 9 uses a vibration unit for intermittent vibration of 5s / time, and only vibrates perpendicular to the injection direction. This vibration mode results in a single direction of fiber precipitation, and a mesh structure cannot be formed, and the bonding strength between the inner and outer layers is poor.

[0091] The above is based on the ideal embodiment of the present invention. Through the above description, relevant personnel can make various changes and modifications without departing from the technical concept of the present invention. The technical scope of the present invention is not limited to the content in the specification, and the technical scope must be determined according to the scope of the claims.

Claims

1. A molding process for a rubber handlebar sheath, characterized in that: The following steps are involved: S1. 80 parts of polyurethane, 0-20 parts of polyacrylonitrile, 0-5 parts of foaming agent, 0-1 part of stabilizer, 0-2 parts of lubricant and 0-1 part of antioxidant are uniformly blended by weight to obtain an inner layer material, and the inner layer injection material is added into the inner layer injection barrel; S2, 100 parts of outer layer rubber material, 0-2 parts of vulcanizing agent, 0-2 parts of accelerator, 0-3 parts of activator, 0-5 parts of reinforcing injection agent, 0-2 parts of plasticizer and 0-1 part of antioxidant are uniformly blended by weight to obtain an outer layer injection material, and the outer layer material is added into the outer layer injection barrel; S3, injecting the outer layer material into the handle cover mold, the outer layer material adheres to the wall of the handle cover mold cavity to form a wear-resistant layer, and the filling degree is set to 30-40%; S4, injecting the inner layer material into the center of the handle cover mold along with the outer layer material until the handle cover mold is 100% filled, the inner layer material is depressurized and foamed after entering the handle cover mold, and polyacrylonitrile is precipitated from the inner layer material along with the foaming gas and migrates to the contact boundary between the inner layer material and the outer layer material, forming a mesh fiber structure spanning the inner layer material and the outer layer material; S5. Lower the temperature of the handlebar cover mold to room temperature, keep it for 5 to 20 minutes without pressure maintenance, and cool and demould the handlebar cover to obtain a rubber handlebar cover.

2. The molding process of the rubber handlebar sheath according to claim 1 is characterized in that: In said S1, the inner layer materials are blended and the inner layer is injected into the barrel at a temperature of 280-350°C and a pressure of 8-20 MPa.

3. The molding process of the rubber handlebar sheath according to claim 1 is characterized in that: The outer layer rubber material is one of vulcanized rubber, styrene-butadiene rubber or chloroprene rubber.

4. The molding process of the rubber handlebar sheath according to claim 1 is characterized in that: In S4, the foaming process of the inner layer material is controlled by using a staged foaming technology, including the following steps: S41, the initial temperature of the handle cover mold is controlled at 80-100°C, and the pressure is controlled at 10-20MPa; S42, initial foaming stage: after the injection of the inner layer material begins, the temperature increases by 5°C every 5 seconds, and the pressure decreases by 1MPa every 5 seconds; S43, the generation and stabilization stage of foaming gas: When the temperature in the handlebar cover mold is 110-120°C, maintain the temperature and pressure for 30-60 seconds; When the temperature in the handlebar cover mold is 130-140°C, maintain the temperature and pressure for 30-60 seconds; When the temperature in the handlebar cover mold is 150-160°C, maintain the temperature and pressure for 30-60 seconds; S44, inner layer material foam curing: The temperature of the handlebar sheath mold is reduced to 80-100°C, and the pressure is reduced to 0.5-1.5MPa for 2-5min.

5. The molding process of the rubber handlebar sheath according to claim 4 is characterized in that: In the above S42 and S43, the handlebar sheath mold is vibrated: the vibration frequency is 15-30 Hz, the vibration amplitude is 60-100 um, and the vibration is cyclically vibrated in multiple directions for 2-5 seconds.

6. The molding process of the rubber handlebar sheath according to claim 1, characterized in that: In the step S4, the injection rate of the inner layer material is 2 to 3 times the injection rate of the outer layer material.

7. A rubber handlebar sheath molding device, based on a rubber handlebar sheath molding process according to any one of claims 1 to 6, characterized in that: include: An injection system, a handlebar cover mold, and a control system for controlling the operation of the injection system and the handlebar cover mold; The injection system comprises: a plurality of injection barrels, a discharge pipe arranged at one side of the injection barrel, and a nozzle arranged at the other end of the discharge pipe; The discharge pipe is a multi-outlet structure, each of which is connected to a plurality of nozzles; The nozzle comprises: a discharge port, an inner material flow channel and an outer material flow channel connected to a discharge pipe; The discharge port is connected to the handle cover mold to inject material therein; The inner layer material flow channel is arranged at the central part of the outer layer material flow channel; The handlebar cover mold comprises: an upper mold and a lower mold combined into a tubular structure cavity, which are used for molding the rubber handlebar cover; The control system includes: a temperature control module, a pressure control module, an injection barrel control module and an automation control module; The temperature control module includes: a plurality of temperature monitoring units and a temperature regulating unit; the plurality of temperature monitoring units are used to monitor the temperature of the injection barrel and the handlebar cover mold respectively, and the plurality of temperature regulating units are used to regulate the temperature of the injection barrel and the handlebar cover mold respectively; The pressure control module includes: a plurality of pressure monitoring units and a pressure regulating unit; the plurality of pressure monitoring units are used to monitor the pressure of the injection barrel and the handlebar cover mold respectively, and the plurality of pressure regulating units are used to regulate the pressure of the injection barrel and the handlebar cover mold respectively; The injection barrel control module is used to control the injection rates of a plurality of injection barrels; The automation control module is used to integrate and control the operation of the injection system, the handle cover mold and the control system, and accurately execute the molding process steps of the rubber handle cover.

8. The rubber handlebar sheath molding device according to claim 7, characterized in that: The plurality of injection barrels include: an inner injection barrel and an outer injection barrel which are independent of each other.

9. The rubber handlebar sheath molding device according to claim 7, characterized in that: The automation control module is provided with a staged foaming mechanism, including: The initial temperature of the handlebar cover mold is controlled at 80-100°C, and the pressure is controlled at 10-20MPa; In the initial foaming stage after the injection of the inner layer material begins: the temperature increases by 5°C every 5s, and the pressure decreases by 1MPa every 5s; Foaming gas generation and stabilization stage: When the temperature in the handlebar cover mold is 110-120° C., the temperature and pressure are maintained for 30-60 seconds; When the temperature in the handlebar cover mold is 130-140° C., the temperature and pressure are maintained for 30-60 seconds; When the temperature in the handlebar cover mold is 150-160° C., the temperature and pressure are maintained for 30-60 seconds; Inner material foam curing: The temperature of the handlebar sheath mold is reduced to 80-100° C., and the pressure is reduced to 0.5-1.5 MPa for 2-5 minutes.

10. The rubber handlebar sheath molding device according to claim 7, characterized in that: The control system further comprises a vibration module, and the vibration module comprises: a plurality of vibration units; the plurality of vibration units are evenly distributed on the outer surface of the handlebar cover mold.

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