A mold for helical gears

Abstract

This invention discloses a mold for helical gears, belonging to the field of gear mold technology. It includes an upper mold assembly and a lower mold assembly. The lower mold assembly has a middle mold core and a lower mold core on its upper side. The middle mold core is rotatably positioned above the lower mold core, and its inner side has internal helical teeth corresponding to the helical gear. A sprue is installed at the center of the lower mold core, with its upper end extending into the middle mold core and connecting with the upper sprue. The upper mold core, upper sprue, middle mold core, lower mold core, and sprue combine to form a molding cavity for the helical gear. The upper end of the lower mold core has several protrusions formed on a concentric circle centered on the center of the middle mold core. A spacer groove is formed between adjacent protrusions, and a guide hole is provided within the spacer groove. An ejector pin is slidably installed within the guide hole, and its lower end is connected to a top plate. The top plate is connected to the output end of a lifting device, which is installed within the lower mold assembly. This invention can reduce the demolding difficulty of helical gears.

Description

Technical Field

[0001] This invention belongs to the field of gear mold technology, and specifically relates to a mold for helical gears. Background Technology

[0002] Unlike spur gears, helical gears have a helix angle in their tooth profile. This means that during demolding, either the tooth cavity plate or the gear part itself needs to rotate to avoid damaging the tooth profile. When the helix angle of the gear is small, the simultaneous rotation of the gear may require a large ejection force, making gear demolding difficult. Summary of the Invention

[0003] In view of this, the purpose of the present invention is to provide a mold for helical gears that can reduce the difficulty of demolding helical gears.

[0004] To achieve the above objectives, the present invention provides the following technical solution: This invention discloses a mold for helical gears, comprising an upper mold assembly and a lower mold assembly. The upper mold assembly has an upper mold core on its lower side, with an upper sprue at its center. The lower mold assembly has a middle mold core and a lower mold core on its upper side. The middle mold core is rotatably positioned above the lower mold core, and its inner side has internal helical teeth corresponding to the helical gear. The lower mold core has a lower sprue at its center, with its upper end extending into the middle mold core and connecting with the upper sprue. The upper mold core, upper sprue, middle mold core, lower mold core, and lower sprue combine to form a molding cavity for the helical gear. The upper end of the lower mold core has several protrusions formed on a concentric circle centered on the center of the middle mold core. A spacer groove is formed between adjacent protrusions, and a guide hole is provided within the spacer groove. An ejector pin is slidably installed within the guide hole, with its lower end connected to a top plate. The top plate is connected to the output end of a lifting device, which is installed within the lower mold assembly.

[0005] Furthermore, the ejector pin includes a limiting plate, a cylindrical section, and a flat section integrally connected from bottom to top. The flat section is slidably disposed within the guide hole, and the width direction of the flat section is along the radial direction of the lower mold core.

[0006] Furthermore, the upper and lower gating columns cooperate to form a collecting cavity. A main channel is formed on the inner side of the upper gating column. The upper end of the main channel extends along the axial direction of the upper gating column and connects to the gate. The lower end of the main channel connects to the collecting cavity. Several branch channels are formed on the lower gating column along the circumferential direction. The branch channels are used to connect the collecting cavity and the molding cavity.

[0007] Furthermore, the protrusion has a vertical air pressure hole, and a piston is slidably disposed within the air pressure hole. A fixing plate is fixed at the upper opening of the air pressure hole, and a first through hole distributed circumferentially is formed on the fixing plate. A rotating plate abuts against the lower side of the fixing plate and is rotatably disposed within the air pressure hole. A piston cavity is formed between the rotating plate and the piston. An air inlet hole communicating with the piston cavity is formed on the lower mold core, and a one-way valve is installed in the air inlet hole. A second through hole distributed circumferentially is formed on the rotating plate, and the first and second through holes correspond to each other. The ejector pin is connected to the piston via a support rod, and the piston is connected to the rotating plate via a linkage assembly. When the ejector pin moves to be flush with the protrusion, the piston acts on the linkage assembly, and the linkage assembly drives the rotating plate to rotate at a certain angle, so that the first and second through holes are aligned.

[0008] Furthermore, the linkage assembly includes a central rod, a reset torsion spring, and a rotating seat. The upper end of the central rod passes through the central hole of the piston and is fixedly connected to the center of the rotating plate. The lower end of the central rod is rotatably connected to the rotating seat fixed to the inner wall of the air pressure hole. A reset torsion spring is installed between the rotating seat and the central rod. An external thread is provided on the outer side of the upper end of the central rod, and an internal thread that mates with the external thread is provided in the central hole of the piston.

[0009] Furthermore, the inner sides of the internal helical teeth are provided with corresponding inclined grooves, and a semiconductor cooling chip is installed at the lower end of the middle mold core. The semiconductor cooling chip is connected to a power supply, and the cold end of the semiconductor cooling chip faces upward and is connected to an inclined heat sink. The inclined heat sink is installed in the inclined groove.

[0010] Furthermore, the two connecting ends of the semiconductor cooling chip are respectively connected to the first contact and the second contact on the outer side of the middle mold core, and the inner side of the lower mold assembly is provided with a first contact ring and a second contact ring corresponding to the first contact and the second contact ring respectively, and the first contact ring and the second contact ring are connected to the power supply.

[0011] Furthermore, the lower mold core is provided with a heat dissipation port corresponding to the hot end of the semiconductor cooling chip. The heat dissipation port corresponds to the heat dissipation channel provided on the lower mold assembly, and a fan is provided on the inner side of the heat dissipation channel.

[0012] The beneficial effects of this invention are as follows: This invention discloses a mold for helical gears. The outer circle of the bottom sprue forms the hole of the helical gear, and the inner helical gear and several mold cores are combined to form the molding cavity of the helical gear. During the casting and molding of the helical gear, since a gap groove is formed between two adjacent protrusions, after the product is formed, the protrusions can be inserted into the bottom of the product to hinder the rotation of the gear. After the gear is lifted by the ejector pin, it can drive the middle mold core to rotate through the cooperation of the spiral groove, realizing demolding while rotating, thus avoiding the demolding difficulty problem of conventional molds.

[0013] In the mold disclosed in this invention, the ejector pin is located in the spacer groove, thus avoiding the protrusion. When the product is lifted, the flat section of the ejector pin corresponds to the length of the spacer groove, thereby increasing the lifting area and making it more convenient for the product to be demolded.

[0014] The mold of the present invention has a coaxial upper and lower sprue, both located at the center of the molding cavity. The upper end of the lower sprue extends into the middle mold core and connects with the upper sprue, allowing for radiating pouring from the center outwards. This makes the product molding more uniform and reduces the demolding difficulty caused by errors.

[0015] Other advantages, objectives, and features of the invention will be set forth in the following description and will be apparent to those skilled in the art in some respects, or may be learned by practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0016] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the following figures are provided for illustration: Figure 1 This is a schematic diagram of the structure of the mold of the present invention; Figure 2 This is a cross-sectional view of the mold core and lower mold core assembly in this invention; Figure 3 for Figure 2 Enlarged view of point A in the middle; Figure 4 This is a schematic diagram of the structure of the inner core. Figure 5 An exploded view of the central model core; Figure 6 This is a schematic diagram of the lower mold core. Figure 7 for Figure 6 Enlarged view of point B in the middle; Figure 8 This is a schematic diagram of the structure of a thimble.

[0017] The following components are labeled in the attached diagram: Upper mold assembly 1, Lower mold assembly 2, Upper mold core 3, Upper sprue 4, Middle mold core 5, Lower mold core 6, Internal inclined tooth 7, Lower sprue 8, Protrusion 9, Spacer groove 10, Guide hole 11, Ejector pin 12, Top plate 13, Lifting device 14, Limiting plate 16, Cylindrical section 17, Flat section 18, Gathering cavity 19, Main runner 20, Sprue 21, Runner 22, Air pressure hole 23, Piston 24, Fixed plate 25, First through hole 26, Rotating plate 27, Piston cavity 28, Air inlet 29, Second through hole 30, Support rod 31, Center rod 32, Return torsion spring 33, Rotating seat 34, External thread 35, Inclined groove 36, Semiconductor cooling chip 37, Inclined heat sink 38, First contact 39, Second contact 40, First connecting ring 41, Second connecting ring 42, Heat dissipation port 43, Heat dissipation channel 44, Fan 45. Detailed Implementation

[0018] like Figures 1-8 As shown, the present invention discloses a mold for helical gears, comprising an upper mold assembly 1 and a lower mold assembly 2. The upper mold assembly 1 is located above the lower mold assembly and is generally square. It can be understood that the structures of the upper mold assembly 1 and the lower mold assembly 2 can also be circular or other polygonal, but they correspond to each other at the mold closing point. An upper mold core 3 is provided on the lower side of the upper mold assembly 1. The upper mold assembly 1 includes an upper template, an upper support plate for mounting the upper template, etc. The upper mold core 3 is located at the center of the upper template, and an upper sprue 4 is installed at the center of the upper mold core 3. The upper end of the upper sprue 4 forms a gate 21, and the lower end extends toward the lower end face of the lower mold core 6.

[0019] Similarly, the upper side of the lower mold assembly 2 is provided with a middle mold core 5 and a lower mold core 6. The upper mold core 3, middle mold core 5, and lower mold core 6 are all circular structures for easy installation. The upper end face of the middle mold core 5 is higher than the upper end face of the lower mold core 6, thus forming part of the molding cavity. The middle mold core 5 is coaxially rotatably positioned on the upper side of the lower mold core 6. The inner side of the middle mold core 5 is provided with an internal helical tooth 7 corresponding to the helical gear. A sprue 8 is installed at the center of the lower mold core 6. The upper end of the sprue 8 extends into the middle mold core 5 and connects with the upper sprue 4. The upper mold core 3, upper sprue 4, middle mold core 5, lower mold core 6, and sprue 8 combine to form the molding cavity for the helical gear.

[0020] In some other embodiments, the upper sprue 4 and the lower sprue 8 can extend into the molding cavity, and an intermediate sprue can be provided between the upper sprue 4 and the lower sprue 8 to replace the mold core of the helical gear, which can facilitate demolding.

[0021] In this invention, the upper end of the bottom sprue 8 extends into the middle mold core 5 and then connects with the top sprue 4, allowing for a radiating pouring from the center outwards. This results in more uniform product molding and reduces demolding difficulties caused by errors. In some other embodiments, the top sprue 4 can also extend downwards into the middle mold core 5 and then connect with the top sprue 4. Using the method of this embodiment, the upper end of the bottom sprue 8 can be flush with the upper end of the middle mold core 5, thus facilitating installation.

[0022] The lower mold core 6 disclosed in this invention has several protrusions 9 on its upper end. The cross-section of the protrusions is trapezoidal, but can also be rectangular or other polygonal. However, the protrusion direction of the protrusions 9 is vertical. The protrusions 9 are formed on a concentric circle with the center of the middle mold core 5 as the center. A spacer groove 10 is formed between two adjacent protrusions 9. A guide hole 11 is provided in the spacer groove 10. An ejector pin 12 is slidably installed in the guide hole 11. The ejector pin 12 can be ejected from the guide hole 11 to achieve demolding. The lower end of the ejector pin 12 is connected to the top plate 13. The top plate 13 is connected to the output end of the lifting device 14. The lifting device 14 is a hydraulic cylinder or a linear motor or other device that can drive the ejector pin 12 to lift. The lifting device 14 is installed in the lower mold assembly 2. After the gear is lifted by the ejector pin 12, it can drive the middle mold core 5 to rotate through the action of the spiral groove, realizing demolding while rotating, thus avoiding the demolding difficulties of conventional molds.

[0023] In this embodiment, the ejector pin 12 includes a limiting plate 16, a cylindrical section 17, and a flat section 18 integrally connected from bottom to top. The flat section 18 is slidably disposed within the guide hole 11, and the width direction of the flat section 18 is along the radial direction of the lower mold core 6. The limiting plate 16 is used to connect the ejector pin 12 to the lower mold assembly 2. The sliding engagement between the cylindrical section 17 and the lower mold assembly 2 facilitates the guidance of the ejector pin 12. The flat section 18 of the ejector pin 12 corresponds to the length of the spacer groove 10, thereby increasing the lifting area without changing the area of ​​the protrusion 9, which can better facilitate the demolding of the product.

[0024] In some other embodiments, the ejector pin 12 may also be a cylindrical shape extending along its axis, thereby facilitating manufacturing. The invention, by designing a flat segment 18, allows for easier placement within the spacer groove 10, thereby facilitating effective lifting of the product during demolding.

[0025] In this embodiment, the upper gating column 4 and the lower gating column 8 cooperate to form a collecting cavity 19. A main channel 20 is formed on the inner side of the upper gating column 4. The upper end of the main channel 20 extends along the axial direction of the upper gating column 4 and connects to the gate 21. The lower end of the main channel 20 connects to the collecting cavity 19. Several branch channels 22 are formed circumferentially on the lower gating column 8. The branch channels 22 are used to connect the collecting cavity 19 and the molding cavity. By dividing the flow through the smaller branch channels 22, it is more conducive to the rapid demolding of the product after molding, reducing material waste. The branch channels 22 spread outward from the center of the collecting cavity 19, which can make the pouring more uniform.

[0026] In this embodiment, a vertical air pressure hole 23 is provided on the protrusion 9, and a piston 24 is slidably disposed in the air pressure hole 23. A fixing plate 25 is fixed at the upper opening of the air pressure hole 23. A first through hole 26 distributed circumferentially is provided on the fixing plate 25. A rotating plate 27 is abutted against the lower side of the fixing plate 25. The rotating plate 27 is rotatably disposed in the air pressure hole 23. A piston cavity 28 is formed between the rotating plate 27 and the piston 24. An air inlet hole 29 communicating with the piston cavity 28 is provided on the lower mold core 6. A one-way valve is installed in the air inlet hole 29. A second through hole 30 distributed circumferentially is provided on the rotating plate 27. The first through hole 26 and the second through hole 30 correspond to each other. The ejector pin 12 is connected to the piston 24 through the support rod 31. The piston 24 is connected to the rotating plate 27 through the linkage assembly. When the ejector pin 12 moves to be flush with the protrusion 9, the piston 24 acts on the linkage assembly. The linkage assembly drives the rotating plate 27 to rotate a certain angle, so that the first through hole 26 and the second through hole 30 are aligned.

[0027] In practical use, when the ejector pin 12 rises under the action of the lifting device 14, the ejector pin 12 can drive the piston 24 to rise together to compress the piston chamber 28. Since the first through hole 26 and the second through hole 30 are staggered and close the air pressure hole 23, the piston 24 has a large air pressure in the piston chamber 28 after it moves. When the piston 24 moves to the upper end, the piston 24 acts on the linkage assembly. After the linkage assembly drives the rotating plate 27 to rotate a certain angle, the first through hole 26 and the second through hole 30 are aligned. At this time, the gas in the piston chamber 28 is suddenly released from the air pressure hole 23. Through the action of instantaneous air pressure, it can be used to assist demolding, and through demolding by air pressure, the surface accuracy of the product can be improved.

[0028] In this embodiment, the linkage assembly includes a central rod 32, a return torsion spring 33, and a rotating seat 34. The central rod 32 is coaxially installed inside the air pressure hole 23. The upper end of the central rod 32 passes through the central hole of the piston 24 and is fixedly connected to the center of the rotating plate 27. The lower end of the central rod 32 is rotatably connected to the rotating seat 34, which is fixed to the inner wall of the air pressure hole 23. A return torsion spring 33 is installed between the rotating seat 34 and the central rod 32. An external thread 35 is provided on the outer side of the upper end of the central rod 32, and an internal thread that mates with the external thread 35 is provided in the central hole of the piston 24. In the normal state, the return torsion spring 33 provides an elastic restoring force to the central rod 32, keeping the central rod 32 in a position where the second through hole 30 on the rotating plate 27 and the first through hole 26 on the fixed plate 25 are offset from each other. The piston 24 engages with the protruding ridge inside the air pressure port 23, allowing for linear movement. When the piston 24 moves upward, its internal thread engages with its external thread 35, causing the piston 24 to rotate the central rod 32 and the rotating plate 27. After rotation, the rotating plate 27 aligns the second through hole 30 with the first through hole 26, thus opening the air pressure port 23. Using this purely mechanical method, the device operates stably, is more suitable for high-temperature environments, and is more cost-effective.

[0029] In this embodiment, the inner sides of the internal helical teeth 7 are provided with corresponding inclined grooves 36. A semiconductor cooling chip 37 is installed at the lower end of the middle mold core 5. The semiconductor cooling chip 37 is connected to a power source, with its cold end facing upwards and connected to an inclined heat sink 38, which is installed within the inclined grooves 36. The inclined heat sink 38, connected to the cold end of the semiconductor cooling chip 37, can cool the internal helical teeth 7, creating a temperature difference between the internal helical teeth 7 and the helical teeth of the product. During demolding, the surface of the helical teeth of the product undergoes slight shrinkage deformation, and the internal force causes the surface of the helical teeth to slide between the surface of the helical teeth and the internal helical teeth 7, thus facilitating demolding.

[0030] In this embodiment, the two connecting ends of the thermoelectric cooler 37 are respectively connected to the first contact 39 and the second contact 40 on the outer side of the middle mold core 5. The inner side of the lower mold assembly 2 is provided with a first ring 41 and a second ring 42 corresponding to the first contact 39 and the second contact 40, respectively. The first ring 41 and the second ring 42 are connected to a power supply. Even after the middle mold core 5 rotates, the first ring 41 and the second ring 42 can still maintain contact with the first contact 39 and the second contact 40 at all times. Connecting to the controller via the power supply allows for more convenient control. In some other embodiments, the thermoelectric cooler 37 can be directly connected to a power supply, which is directly mounted on the middle mold core 5 and rotates with it, thus avoiding the problem of ineffective power supply installation. While this method is beneficial for a compact structure, it makes it difficult to replace the power supply in a timely manner, resulting in inconvenience.

[0031] In this embodiment, the lower mold core 6 has a heat dissipation port 43 corresponding to the hot end of the thermoelectric cooler 37. The heat dissipation port 43 dissipates heat from the hot end of the thermoelectric cooler 37. The heat dissipation port 43 corresponds to a heat dissipation channel 44 on the lower mold assembly 2. A fan 45 is provided inside the heat dissipation channel 44. The fan 45 can be connected to an external motor and can be used to dissipate heat from the hot end of the thermoelectric cooler 37, maintaining its good working performance at all times. In some other embodiments, the fan 45 can also be other cooling components, the purpose of which is to keep the thermoelectric cooler 37 in good working condition by dissipating heat from the hot end of the thermoelectric cooler 37.

[0032] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made to it in form and detail without departing from the scope defined by the claims of the present invention.

Claims

1. A mold for helical gears, characterized in that: The mold includes an upper mold core (3), a middle mold core (5), and a lower mold core (6). The upper mold core (3), middle mold core (5), and lower mold core (6) are assembled from top to bottom to form a molding cavity for a helical gear. The middle mold core (5) is rotatably disposed on the upper side of the lower mold core (6). The inner side of the middle mold core (5) is provided with an internal helical tooth (7) corresponding to the helical gear. The upper end of the lower mold core (6) is provided with several protrusions (9). The protrusions (9) are formed on a concentric circle with the center of the middle mold core (5) as the center. An interval groove (10) is formed between two adjacent protrusions (9). A guide hole (11) is provided in the interval groove (10). A push pin (12) is slidably installed inside the device. The lower end of the push pin (12) is connected to the top plate (13), and the top plate (13) is connected to the output end of the lifting device (14). A vertical air pressure hole (23) is opened on the protrusion (9). A piston (24) is slidably installed inside the air pressure hole (23). A fixing plate (25) is fixed at the upper opening of the air pressure hole (23). A first through hole (26) distributed circumferentially is opened on the fixing plate (25). A rotating plate (27) abuts against the lower side of the fixing plate (25). The rotating plate (27) is rotatably installed inside the air pressure hole (23). Between the rotating plate (27) and the piston (24) A piston cavity (28) is formed. An air inlet (29) communicating with the piston cavity (28) is provided on the lower mold core (6). A one-way valve is installed in the air inlet (29). A second through hole (30) distributed circumferentially is provided on the rotating plate (27). The first through hole (26) and the second through hole (30) correspond to each other. The ejector pin (12) is connected to the piston (24) through the support rod (31). The piston (24) is connected to the rotating plate (27) through the linkage assembly. When the ejector pin (12) moves to be flush with the protrusion (9), the piston (24) acts on the linkage assembly. The linkage assembly drives the rotating plate (27) to rotate a certain angle, so that... The first through hole (26) and the second through hole (30) are aligned; the linkage assembly includes a central rod (32), a reset torsion spring (33) and a rotating seat (34). The upper end of the central rod (32) passes through the central hole of the piston (24) and is fixedly connected to the center of the rotating plate (27). The lower end of the central rod (32) is rotatably connected to the rotating seat (34) fixed to the inner wall of the air pressure hole (23). A reset torsion spring (33) is installed between the rotating seat (34) and the central rod (32). An external thread (35) is opened on the outer side of the upper end of the central rod (32). An internal thread that mates with the external thread (35) is opened in the central hole of the piston (24).

2. The mold for helical gears according to claim 1, characterized in that: The mold also includes an upper mold assembly (1) and a lower mold assembly (2). The upper mold assembly (1) has an upper mold core (3) on its lower side. An upper sprue (4) is installed in the center of the upper mold core (3). The lower mold assembly (2) has a middle mold core (5) and a lower mold core (6) on its upper side. A lower sprue (8) is installed in the center of the lower mold core (6). The upper end of the lower sprue (8) extends into the middle mold core (5) and connects with the upper sprue (4). The lifting device (14) is installed in the lower mold assembly (2).

3. The mold for helical gears according to claim 2, characterized in that: The ejector pin (12) includes a limiting plate (16), a cylindrical section (17) and a flat section (18) integrally connected from bottom to top. The flat section (18) is slidably disposed in the guide hole (11), and the width direction of the flat section (18) is along the radial direction of the lower mold core (6).

4. A mold for helical gears according to claim 3, characterized in that: The upper gating column (4) and the lower gating column (8) cooperate to form a collecting cavity (19). A main channel (20) is formed on the inner side of the upper gating column (4). The upper end of the main channel (20) extends along the axial direction of the upper gating column (4) and connects to the gate (21). The lower end of the main channel (20) is connected to the collecting cavity (19). Several branch channels (22) are opened on the lower gating column (8) along the circumferential direction. The branch channels (22) are used to connect the collecting cavity (19) and the molding cavity.

5. A mold for helical gears according to any one of claims 1-4, characterized in that: The inner side of the inner helical tooth (7) is provided with a corresponding inclined groove (36). The lower end of the middle mold core (5) is equipped with a semiconductor cooling chip (37). The semiconductor cooling chip (37) is connected to the power supply. The cold end of the semiconductor cooling chip (37) faces upward and is connected to the inclined heat sink (38). The inclined heat sink (38) is installed in the inclined groove (36).

6. A mold for helical gears according to claim 5, characterized in that: The two connecting ends of the semiconductor cooling chip (37) are respectively connected to the first contact (39) and the second contact (40) on the outside of the middle mold core (5). The inner side of the lower mold assembly (2) is provided with a first ring (41) and a second ring (42) corresponding to the first contact (39) and the second contact (40) respectively. The first ring (41) and the second ring (42) are connected to the power supply.

7. A mold for helical gears according to claim 6, characterized in that: The lower mold core (6) has a heat dissipation port (43) corresponding to the hot end of the semiconductor cooling chip (37). The heat dissipation port (43) corresponds to the heat dissipation channel (44) on the lower mold assembly (2). A fan (45) is provided on the inner side of the heat dissipation channel (44).

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