A vulcanization mold for a rubber case with a metal insert

Abstract

The application discloses a vulcanization mold for rubber shell with metal inserts, which comprises a lower mold, a middle mold and an upper mold, the lower mold, the middle mold and the upper mold are surrounded to form a mold cavity, the upper mold is provided with a plurality of downward arranged upper positioning pins, the upper mold is further provided with an upper mold pressing plate, a spring is arranged on each upper positioning pin in one-to-one correspondence, the lower end of the spring is in abutment with the upper end of the upper positioning pin, and the upper end of the spring is in abutment with the upper mold pressing plate; a downward arranged lower positioning pin in one-to-one correspondence with the upper positioning pin is arranged in the middle mold cavity, the number of the lower positioning pins is consistent with the number of the metal inserts to be placed, and when the metal inserts are placed in the mold cavity of the middle mold, the corresponding upper positioning pins and lower positioning pins are respectively inserted into the inner cavities at the upper and lower ends of the metal inserts and position the metal inserts. The vulcanization mold can adapt to the semi-automatic production of a 3RT vulcanization machine, can quickly fill glue, quickly demold and does not need to clean the residual glue in the internal cylindrical holes of the inserts.

Description

Technical fields:

[0001] This invention relates to the field of mold design and development technology, specifically to a vulcanizing mold with a rubber shell and metal inserts. Background technology:

[0002] To enhance performance, inserts are sometimes added to rubber products for integral vulcanization molding. However, the addition of inserts increases the complexity of the process, specifically in terms of fixing and positioning the inserts in the mold, deformation of the inserts under pressure, and protection of the internal space of the inserts.

[0003] To prevent inserts from being compressed or misaligned, a method of injecting adhesive is typically used to guide the adhesive material away from the insert, thus solving both compression and misalignment issues. There are two existing methods: one is to use the material cylinder built into the vulcanizing machine for injection, and the other is to add a material hopper outside the mold cavity, with the hopper connected to the cavity by a hole. Both methods result in some material loss.

[0004] The characteristics of the insert itself, such as its pressure-bearing capacity and geometry, also affect the mold design. In particular, when the insert is a hollow cylinder, it is axially oriented and placed upright during vulcanization. During the pressurized filling stage, the rubber material will enter the internal space of the insert, causing difficulties for the post-processing of the product.

[0005] Furthermore, there are two common methods for fixing inserts: one is bolt fixing, which is time-consuming and labor-intensive for disassembling and assembling the mold; the other is to design locating pins on the mold and make clearance fit with the inserts, which can interfere with the filled adhesive and makes cleaning excess adhesive inconvenient.

[0006] With the development of the vulcanizing machine industry, there are now 3RT vulcanizing machines on the market that can achieve semi-automatic production, reduce the labor intensity of workers, reduce labor costs, and improve production efficiency. In order for the 3RT vulcanizing machine to play its due role, it is important to design a matching vulcanizing mold. Therefore, the vulcanizing mold with a rubber shell and metal inserts designed in this patent is the key. It is necessary to design an operable mold that can achieve the process, is easy to operate, and is suitable for mass production. Summary of the Invention:

[0007] The technical problem to be solved by the present invention is to provide a vulcanizing mold for a rubber shell with metal inserts. This vulcanizing mold for a rubber shell with metal inserts can be adapted to semi-automatic production of a 3RT vulcanizing machine, and can quickly fill rubber, quickly demold, and eliminate the need to clean excess rubber from the cylindrical holes inside the inserts.

[0008] The technical solution of this invention is to provide a vulcanizing mold for a rubber shell with metal inserts, comprising a lower mold, a middle mold, and an upper mold. The lower mold, middle mold, and upper mold together form a cavity. The upper mold is provided with a plurality of downwardly positioned upper positioning pins and an upper mold pressure plate. A spring is correspondingly mounted on each upper positioning pin, with the lower end of the spring abutting against the upper end of the upper positioning pin and the upper end of the spring abutting against the upper mold pressure plate. The middle mold cavity is provided with upwardly positioned lower positioning pins corresponding to the upper positioning pins. The number of lower positioning pins is consistent with the number of metal inserts to be placed. When a metal insert is placed into the middle mold cavity, the corresponding upper and lower positioning pins are respectively inserted into the inner cavities at the upper and lower ends of the metal insert and position the metal insert. This structure overcomes the traditional method of fixing inserts in existing technologies, solving problems such as deformation under pressure, displacement under pressure, internal residual adhesive cleaning, and adhesive waste in hollow insert structures.

[0009] Specifically, the spring properties are used to keep the upper positioning pin and the metal insert with the rubber shell of the metal insert in a state of increasing pressure. During the vulcanization molding process, excess rubber material will not be squeezed into the cylindrical hole inside the metal insert, thus eliminating the need to repair excess rubber in the cylindrical hole inside the metal insert. At the same time, the combination of the internal pressure spring and the positioning pin is used to fix the cylindrical hollow metal insert. Since the metal insert and the mold are connected by a soft connection of spring and positioning pin, mutual damage or deformation between the metal insert and the mold can be avoided.

[0010] Alternatively, a more reasonable approach is to accommodate the spring through a through-hole in the upper mold, preventing it from shifting during compression. The spring is assembled between the upper locating pin and the upper mold pressure plate. Based on the spring's characteristics, the closing pressure is transmitted to the middle mold, ensuring that the middle and lower molds remain in a state of increasing pressure during the closing process. This reduces the amount of plastic material squeezed into the mold gap between the middle and lower molds, ensuring the product dimensions and the amount of flash. Preferably, a mold-specific spring is used. The appropriate specification and model can be selected based on the formula: Ultimate Pressure ÷ (Length × Compression Ratio) = Force Generated per Millimeter of Compression. The number of springs selected should be the same as the number of metal inserts.

[0011] Preferably, the outer diameter of the insertion portion of the upper and lower locating pins that engages with the metal insert is clearance-fitted with the inner diameter of the metal insert. In other words, the portion of the upper and lower locating pins used to engage with the cylindrical hole of the metal insert can be designed as a conical structure or a tapered guide portion, as well as a constant-diameter portion that perfectly matches the inner diameter of the metal insert. This completely blocks both ends of the metal insert, preventing excess adhesive from being squeezed into the cylindrical hole inside the metal insert during the vulcanization molding process.

[0012] Preferably, a variable material hopper is provided on the upper part of the middle mold. The variable material hopper is located above the middle mold cavity, and its inner cross-section is clearance-fitted with the cross-section of the middle mold cavity. Considering the mold closing requirements of the upper and middle molds, the inner cavity of the variable material hopper is not smaller than the cross-section of the middle mold cavity. Thus, during the mold closing process, as the upper mold moves downwards, the space for storing rubber in the variable material hopper gradually decreases until it reaches zero. Using the variable material hopper design, there is no need for rubber injection molding equipment with a barrel. The rubber is filled by pressure applied by the upper mold boss. During this process, the volume of the variable material hopper gradually decreases until it disappears when the mold is fully closed. The variable material hopper uses an easily machinable straight-face clearance fit, meaning that the connection between the variable material hopper and the upper part of the middle mold is outwards to form a stepped surface, which is also the mold bearing surface. Furthermore, with the variable material hopper designed in this middle mold, pre-cut pieces of rubber of a certain weight according to the hopper size are placed into the hopper to complete the filling process, achieving rapid filling.

[0013] Preferably, the inner wall of the middle mold cavity is also equipped with a middle mold parting surface. The inclined surface of the middle mold parting surface and the inclined surface of the lower mold protrusion form the mold cavity. The parting surface of the middle mold and the lower mold have a 9° die-off angle and a clearance fit. The middle mold parting surface is designed around the inner wall of the product. When the middle mold and the lower mold separate, the product is quickly pulled out by the middle mold, and then ejected by the demolding frame installed on the lower part of the 3RT vulcanizing machine, achieving rapid demolding.

[0014] Preferably, the middle mold is also equipped with lifting lugs on both sides that are compatible with the medium lifting mechanism of the vulcanizing machine. When the mold moves forward and backward with the lower hot plate, the lifting lugs of the middle mold can freely enter and exit the medium lifting mechanism of the 3RT vulcanizing machine. After the lifting lugs of the middle mold enter the medium lifting mechanism of the 3RT vulcanizing machine, the middle mold can move up and down with the medium frame of the 3RT vulcanizing machine. When the product is demolded, the middle mold moves up to separate the product from the lower mold, which can realize the demolding of the mold driven by the vulcanizing machine without manual operation.

[0015] Preferably, the upper mold has four connecting rollers on both sides for connecting and cooperating with the upper mold lifting mechanism of the vulcanizing machine. By setting the connecting rollers, it is convenient to connect and cooperate with the upper mold lifting mechanism of the vulcanizing machine, thereby realizing the upward, flipping and downward movement of the upper mold.

[0016] Preferably, a demolding frame is also included, which has protrusions that mate with the inner cavity of the rubber housing with metal inserts. The outline and dimensions of the protrusions are slightly smaller than the inner cavity dimensions of the rubber housing with metal inserts, and the height of the protrusions is also designed based on the inner cavity height of the rubber housing with metal inserts and the parting surface height of the middle mold, so as to eject the product during demolding.

[0017] Preferably, the lower mold has four mounting and fixing slots, and four standard guide pillars are assembled on the upper surface of the lower mold. The four standard guide pillars cooperate with four standard guide sleeves set on the lower surface of the middle mold, thereby fixing the middle mold on the lower mold.

[0018] Preferably, the upper mold and the upper mold platen are connected and positioned by guide pillars and connected as one piece by hexagonal screws.

[0019] Compared with the prior art, the present invention has the following advantages after adopting the above structure: The spring in this mold design is assembled between the upper positioning pin and the upper mold platen. Utilizing the spring's characteristics, the upper positioning pin and the metal insert with the metal insert rubber shell are always kept in a compressed state. During the vulcanization molding process, excess rubber material will not be squeezed into the internal cylindrical hole of the metal insert, eliminating the need for repairing excess rubber in the internal cylindrical hole of the metal insert; and based on the spring's characteristics, the mold closing pressure is transmitted to the middle mold, ensuring that the middle mold and lower mold are always in a state of increasing pressure during the mold closing process, reducing the amount of rubber material squeezed into the mold closing gap between the middle mold and lower mold, and ensuring… This invention ensures product dimensions and flash glue quantity; it solves problems such as deformation under pressure, pressure-induced misalignment, internal residual glue cleaning, and glue waste in hollow structure inserts; simultaneously, the variable hopper design eliminates the need for rubber injection molding equipment with a hopper, allowing the glue to fill the mold through pressure applied by the upper mold boss. During this process, the variable hopper volume gradually decreases until it disappears when the mold is fully closed; furthermore, this invention utilizes an internal pressure spring and locating pin combination to fix the metal insert. Because the metal insert and mold are connected by a soft connection using a spring and locating pin combination, mutual damage or deformation between the metal insert and the mold is avoided. Attached image description:

[0020] Figure 1 This is an assembly diagram of a vulcanizing mold for a rubber shell with metal inserts according to an embodiment of the present invention.

[0021] Figure 2 for Figure 1 Enlarged schematic diagram at point I in the middle.

[0022] Figure 3 This is a three-dimensional partial cross-sectional view of the vulcanization mold for the rubber shell with metal inserts of the present invention.

[0023] Figure 4 This is a three-dimensional view of the middle mold of the vulcanizing mold for the rubber shell with metal inserts of the present invention.

[0024] Figure 5 This is a partial assembly view of the upper locating pin, lower locating pin, spring, and metal insert of the present invention.

[0025] Figure 6 This is a partial three-dimensional cross-sectional view of the rubber housing with metal inserts of the present invention. Detailed implementation method:

[0026] The present invention will be further described below with reference to the accompanying drawings and specific embodiments:

[0027] like Figure 1-6As shown in the figure, this embodiment of a vulcanizing mold for a rubber shell with metal inserts includes a lower mold 1, a middle mold 2, an upper mold 3, an upper mold pressure plate 4, a standard guide post 5, a standard guide sleeve 6, a guide post 7, a lower positioning pin 8, an upper positioning pin 9, a spring 10, a connecting roller 11, and a demolding frame 12. The lower mold 1, the middle mold 2, and the upper mold 3 constitute the mold cavity.

[0028] In this embodiment, it is illustrated that one mold can be used to form 9 vulcanized products. The upper mold 3 is provided with 9*4=36 downwardly positioned upper positioning pins 9. The upper mold 3 is also provided with an upper mold pressure plate 4. The upper mold 3 and the upper mold pressure plate 4 are connected and positioned by guide pillars 7 and connected as one piece by internal hexagon screws. A spring 10 is provided on each of the upper positioning pins 9. The lower end of the spring 10 abuts against the upper end of the upper positioning pin 9, and the upper end of the spring 10 abuts against the lower surface of the upper mold plate 4. The cavity of the middle mold 2 is provided with 36 lower positioning pins 8 that are provided upwardly and correspond one-to-one with the upper positioning pins 9. The number of lower positioning pins 8 is the same as the number of metal inserts 13 to be placed. When the metal insert 13 is placed into the cavity of the middle mold 2, the corresponding upper positioning pins 9 and lower positioning pins 8 are respectively inserted into the cylindrical cavities at the upper and lower ends of the metal insert 13 and position the metal insert 13. That is to say, the upper positioning pins 9 and lower positioning pins 8 are respectively inserted into the upper and lower ends of the metal insert 13 and completely block its opening. This can prevent excess rubber material from being squeezed into the cylindrical hole inside the metal insert during the vulcanization molding process. At the same time, with the cooperation of the springs 10, a soft connection can be achieved between the metal insert 13 and the mold by using a combination of springs and positioning pins, so as to avoid mutual damage or deformation between the metal insert 13 and the mold. The above structure breaks through the traditional method of fixing inserts in existing technologies, and solves problems such as deformation under pressure, displacement under pressure, internal residual adhesive cleaning, and adhesive waste of hollow structure inserts.

[0029] Additionally, a more reasonable approach is to accommodate the spring 10 through a through-hole in the upper mold, preventing it from shifting during compression. The spring 10 is assembled between the upper locating pin 9 and the upper mold pressure plate 4. Based on the spring's characteristics, the closing pressure is transmitted to the middle mold 2, ensuring that the middle mold 2 and the lower mold 1 remain in a state of increasing pressure during mold closing, reducing the amount of adhesive material squeezed into the mold gap between the middle mold 2 and the lower mold 1, and ensuring the product dimensions and the amount of flash adhesive. Preferably, the spring 10 is a mold-specific spring, and its appropriate specification and model can be selected according to the formula: ultimate pressure ÷ (length × compression ratio) = force generated per millimeter of compression. The number of springs 10 selected is the same as the number of metal inserts 13.

[0030] Nine variable material bins 21 are provided on the upper part of the middle mold 2 for filling rubber compound. The variable material bins 21 are located above the mold cavity of the middle mold 2. The cross-section of the inner cavity of the variable material bins 21 is adapted to the cross-section of the cavity of each vulcanized product of the middle mold 2. In this embodiment, the cross-section of the inner cavity of the variable material bins 21 is consistent with the cross-sectional shape and size of the mold cavity of the middle mold 2. The cavity size is determined according to the shrinkage rate of the rubber compound used and the product drawing size. The bottom of the variable material bins 21, i.e., the parting surface between the upper mold 3 and the middle mold 2, is also the mold bearing surface. The theoretical calculation formula for the minimum bearing area of ​​the mold is as follows:

[0031]

[0032] In the formula, Amin represents the minimum bearing area of ​​the mold (cm²). 2 );

[0033] In the formula, F represents the hydraulic tonnage of the mold vulcanizing machine (kN).

[0034] In the formula, [σ] represents the allowable stress (MPa) of the material used in the mold.

[0035] The rationality of the bearing area is verified by calculating the results of this formula. After the design is completed, it is processed by a CNC machining center. The variable material hopper 21 design eliminates the need for rubber injection molding equipment with a material cylinder. The rubber material can be filled into the mold by applying pressure through the upper mold boss. During this process, the volume of the variable material hopper gradually decreases until it disappears when the mold is fully closed.

[0036] The inner wall of the middle mold 2 cavity is also surrounded by middle mold parting surfaces 22. The inclined surface of the middle mold parting surface 22 and the inclined surface of the protruding part of the lower mold 1 cooperate to form the mold cavity. The parting surface of the middle mold parting surface 22 and the lower mold 1 are fitted with a 9° mold-removal angle and a clearance fit. The middle mold parting surface 22 is designed around the inner wall of the product. When the middle mold 2 and the lower mold 1 separate, the middle mold 2 quickly pulls out the product, and then the demolding frame 12 installed on the lower part of the 3RT vulcanizing machine moves upward to eject the product, achieving rapid demolding.

[0037] The following is a detailed explanation of the use of this mold in conjunction with the vulcanizing machine: Based on the equipment interface provided by the lower hot plate of the 3RT vulcanizing machine, four mounting slots are designed on the lower mold 1. The lower mold 1 is fixed to the lower hot plate of the 3RT vulcanizing machine using T-nuts, flat washers, and hex socket screws. The mold will not move when it moves forward or backward with the lower hot plate. Four standard guide pillars 5 are installed on the upper surface of the lower mold 1, which cooperate with the four standard guide sleeves 6 designed and installed on the lower surface of the middle mold 2 to fix the middle mold 2 onto the lower mold 1.

[0038] Based on the equipment interface provided by the 3RT vulcanizing machine's intermediate frame, the intermediate mold 2 is designed with lifting lugs on both sides. As the mold moves forward and backward with the lower hot plate, the lifting lugs of the intermediate mold 2 can freely enter and exit the 3RT vulcanizing machine's intermediate lifting mechanism. After entering the 3RT vulcanizing machine's intermediate lifting mechanism, the intermediate mold 2 can move upward and downward with the 3RT vulcanizing machine's intermediate lifting mechanism. During product demolding, the intermediate mold 2 moves upward, separating the product from the lower mold 1, allowing the vulcanizing machine to drive the mold demolding without manual operation. Each product's mold cavity bottom of the intermediate mold 2 has four lower positioning pins 8 at the four corners for installing metal inserts 13. The intermediate mold 2 is designed with nine variable material bins 21. Pre-cut pieces of rubber material of a certain weight are placed into the bins according to the bin size for rapid filling. The upper surface of the intermediate mold 2 is designed to be equipped with four standard guide sleeves 6, which cooperate with the lower surface of the upper mold 3, which is equipped with four standard guide pillars 5, achieving the mold closing requirements between the intermediate mold 2 and the upper mold 3.

[0039] The upper mold 3 of this mold is embedded with 36 upper positioning pins 9 and springs 10. The upper mold 3 and the upper mold pressure plate 4 are positioned by guide pillars 7 and connected as a whole by 9 hexagonal screws. According to the equipment interface provided by the upper mold frame of the 3RT vulcanizing machine, the upper mold 3 is designed with 4 connecting rollers 11 on both sides to connect and cooperate with the rollers of the upper mold lifting mechanism of the vulcanizing machine. By setting the connecting rollers, it is easy to connect and cooperate with the upper mold lifting mechanism of the vulcanizing machine, thereby realizing the upward, flipping and downward movement of the upper mold. When the upper mold lifting mechanism of the 3RT vulcanizing machine moves upward, it supports the 4 connecting rollers 11 to separate the upper mold 3 and the upper mold pressure plate 4 from the middle mold 2 of the mold, thus achieving the purpose of demolding.

[0040] The mold is designed with a demolding frame 12. According to the equipment interface provided by the lower platen of the 3RT vulcanizing machine, the demolding frame 12 has four countersunk holes for cylindrical head screws at its four corners. The demolding frame is fixed to the lower platen of the 3RT vulcanizing machine through these four holes. The demolding frame is designed with nine protrusions whose outer contour dimensions are slightly smaller than the inner cavity dimensions of the rubber shell with metal inserts. The height of the protrusions is designed according to the inner cavity height of the rubber shell with metal inserts and the height of the middle mold parting surface 22.

[0041] When the set vulcanization time is reached, the lower heating plate of the 3RT vulcanizing machine lowers the mold as a whole downwards. Once in position, the lower heating plate retracts the mold as well. Then, the upper lifting mechanism of the 3RT vulcanizing machine raises the upper mold 3 and upper mold pressure plate 4 as a whole, separating the upper mold 3 from the middle mold 2. After reaching the upper position, the middle lifting mechanism of the 3RT vulcanizing machine raises the middle mold 2. The middle mold 2, through the middle mold parting surface 22, detaches the rubber shell with metal inserts from the lower mold 1. After reaching the upper position, the lower heating plate of the 3RT vulcanizing machine moves the lower mold 1 forward, creating space for the lower platen of the 3RT vulcanizing machine to raise the mold release frame 12. The mold release frame 12 then ejects the rubber shell with metal inserts, achieving complete demolding. This achieves semi-automatic production.

[0042] The process of mold working in conjunction with 3RT vulcanizing machine is as follows:

[0043] 1. After preheating is complete, the pressure is released, the entire mold is withdrawn, and the upper mold lifting mechanism lifts the upper mold;

[0044] 2. Install the metal insert;

[0045] 3. Cut appropriate amounts of rubber material and fill them into the variable material hopper of the middle mold;

[0046] 4. The upper lifting mechanism descends, and the upper mold is guided into the middle mold through the guide pillars. The standard guide pillars and guide sleeves determine the positioning relationship with the middle mold.

[0047] 5. Push the mold into the vulcanizing machine, raise the mold to the set position, lower the vacuum hood of the vulcanizing machine to create a vacuum, close the mold and apply pressure;

[0048] 6. Vulcanization;

[0049] 7. Release the pressure and remove the entire mold;

[0050] 8. The upper lifting mechanism moves upward, and the upper mold disengages;

[0051] 9. The middle mold rises and separates from the lower mold;

[0052] 10. The lower mold moves forward;

[0053] 11. The lower mold, along with the demolding frame, moves upwards to eject the product and remove it from the mold.

[0054] The lower mold exits and overlaps with the middle and upper molds in the vertical direction, entering the next mold cycle.

Claims

1. A vulcanizing mold for a rubber shell with metal inserts, comprising a lower mold, a middle mold, and an upper mold, characterized in that: The lower mold, middle mold, and upper mold are assembled to form a cavity. The upper mold has several downward-facing upper positioning pins and an upper mold pressure plate. Each upper positioning pin has a corresponding spring, with the lower end of the spring abutting against the upper end of the upper positioning pin and the upper end of the spring abutting against the upper mold pressure plate. The middle mold cavity has upward-facing lower positioning pins that correspond to the upper positioning pins. The number of lower positioning pins is the same as the number of metal inserts to be placed. When a metal insert is placed into the middle mold cavity, the corresponding upper and lower positioning pins are inserted into the inner cavities at the upper and lower ends of the metal insert and position the metal insert. The upper part of the middle mold has a variable material bin, which is located above the middle mold cavity and its inner cross-section is adapted to the cross-section of the middle mold cavity. The inner wall of the middle mold cavity is also distributed with middle mold parting surfaces. The inclined surface of the middle mold parting surface and the inclined surface of the lower mold protrusion parting surface cooperate to form the mold cavity. The middle mold parting surface and the lower mold cooperating part adopt a 9° mold-removing angle and clearance fit. The upper mold and the upper mold pressure plate are connected and positioned by guide pillars.

2. The vulcanizing mold with a rubber shell and metal insert as described in claim 1, characterized in that: The outer diameter of the insertion part of the upper and lower positioning pins that engages with the metal insert is adapted to the inner diameter of the metal insert.

3. The vulcanizing mold with a rubber shell and metal insert as described in claim 1, characterized in that: The middle mold is also equipped with lifting lugs on both sides to match the medium lifting mechanism of the vulcanizing machine.

4. The vulcanizing mold with a rubber shell and metal insert as described in claim 1, characterized in that: The upper mold has four connecting rollers on both sides for connecting and cooperating with the upper mold lifting mechanism of the vulcanizing machine.

5. The vulcanizing mold with a rubber shell and metal insert according to claim 1, characterized in that: It also includes a demolding frame, which has protrusions that mate with the inner cavity of the rubber housing of the metal insert.

6. The vulcanizing mold with a rubber shell and metal insert according to claim 1, characterized in that: The lower mold has four mounting and fixing slots, and four standard guide pillars are assembled on the upper surface of the lower mold. The four standard guide pillars cooperate with four standard guide sleeves set on the lower surface of the middle mold to fix the middle mold on the lower mold.

Images