Injection mold for helical gears

Abstract

The utility model belongs to injection mold technical field, concretely relates to a helical gear injection mold, including upper die plate and lower die plate, be provided with at least one opening of cylindrical forming cavity of lower die plate to upper die plate in upper die plate, be equipped with the first forming groove, second forming groove and the forming boss, recess, boss of coaxial setting of forming cavity in upper die plate one end away from upper die core, one side of upper die plate and upper die core is equipped with the first forming area, second forming area, the lower die plate is equipped with the installation groove of opening to upper die plate in corresponding with forming cavity in lower die plate, be provided with lower die core in the installation groove, be provided with upper die core in the installation groove between lower die core and upper die plate, one side of upper die core to upper die plate is equipped with the third forming groove with the first forming area, second forming area corresponding, through the setting of above -mentioned component, not only promotes the forming quality when helical gear production and improves production efficiency.

Description

Technical Field

[0001] This utility model belongs to the technical field of injection mold equipment, and specifically relates to a helical gear injection mold. Background Technology

[0002] Injection molding, as a core processing technology for mass production of complex structural components in precision manufacturing, is widely used in the manufacturing of parts for automotive components, intelligent devices, and precision instruments due to its advantages of one-time molding of complex structures, high production efficiency, and good dimensional stability. Its working principle is as follows: after heating and melting the polymer material, the molten material is injected into a mold with a pre-set cavity using an injection molding machine under high pressure. After the material cools and solidifies within the cavity, forming a structure consistent with the shape of the cavity, the mold is opened, and the molded part is removed through a demolding mechanism, ultimately obtaining the desired finished product.

[0003] In the field of precision transmission, internal helical gears, due to their characteristics of smooth transmission, high load-bearing capacity, and high space utilization, have become key core components in equipment such as miniature reducers, intelligent lock mechanisms, and small servo motors. For example... Figure 11 , 12 As shown, the teeth of the internal helical gear are distributed in a spiral shape on the inner wall of the gear hole, which is different from the external tooth structure of the conventional external helical gear. The forming process of the internal helical gear requires the mold to form a spiral tooth cavity inside the gear. At the same time, the internal helical gear has a through hole structure in the middle and some protrusions on the outside of the internal helical gear for positioning, connection or cooperation with other components.

[0004] However, there is currently no specific industry standard for such... Figure 11 , 12 The image shows an injection mold for an internal helical gear. Existing molds used for internal helical gear production are mostly simple modifications of external helical gear injection molds. For example, an internal gear forming structure is added directly inside the mold core of the original external helical gear mold, or the position of the ejection mechanism is adjusted to suit the demolding requirements of the internal gear. However, such modifications have significant drawbacks: Firstly, the cavity design, force distribution, and material filling path of the external helical gear mold are all centered around the external tooth shape. After modification, it is difficult to match the forming requirements of the internal helical gear's inner tooth cavity, resulting in internal helical gears often exhibiting problems such as incomplete tooth shape, helix angle deviation, and out-of-tolerance inner hole dimensions, leading to a low product qualification rate. Secondly, the modified mold lacks demolding guides and cavity positioning structures adapted to the internal helical gear structure, making it prone to uneven filling of material in the corners of the inner tooth cavity during production, resulting in low production efficiency, a low product qualification rate, and increased production costs.

[0005] In summary, regarding such Figure 11 , 12The existing modification schemes for the internal helical gear shown cannot meet the requirements for molding accuracy and production efficiency. Currently, there is a lack of dedicated injection molds in the industry to ensure the stability of mass production and high-quality production of this internal helical gear. Summary of the Invention

[0006] The purpose of this invention is to provide a helical gear injection mold, aiming to solve the problems of existing internal helical gear injection molds in terms of... Figure 11 , 12 The technical problems shown are poor forming quality and low production efficiency in the production of internal helical gears.

[0007] To achieve the above objectives, this utility model provides a helical gear injection mold, comprising an upper mold plate and a lower mold plate. The upper mold plate has at least one cylindrical molding cavity with its opening facing the lower mold plate. The upper mold plate has a first molding groove, a second molding groove, and molding protrusions, grooves, and bosses coaxially arranged with the molding cavity at the end of the molding cavity away from the upper mold core. The side of the upper mold plate adjacent to the upper mold core has a first molding area and a second molding area. The upper mold plate also has multiple injection holes that penetrate the molding cavity. The lower mold plate has corresponding injection holes... The device has an installation groove with an opening facing the upper template. A lower mold core is provided in the installation groove. An upper mold core is provided between the lower mold core and the upper template, located in the installation groove. A third forming groove is provided on the side of the upper mold core facing the upper template, corresponding to the first forming area and the second forming area. A through hole is provided coaxially with the upper mold core and the lower mold core, penetrating the upper mold core and the lower mold core. A base is rotatably provided in the through hole. A forming insert is provided at the end of the base facing the upper mold core. The forming insert protrudes from the through hole in the upper mold core. A mating post is provided at the end of the forming insert away from the lower mold core.

[0008] Preferably, the boss is located in the forming protrusion and the height of the boss is less than the height of the forming protrusion, and the groove is located around the boss.

[0009] Preferably, the molding protrusion is provided with molding posts, and there are multiple molding posts. When the internal helical gear is injection molded, the molding posts abut against the side of the molding insert facing the upper template.

[0010] Preferably, the mating post and the boss are coaxially arranged, and when the internal helical gear is injection molded, the mating post and the boss are abutted together.

[0011] Preferably, the first forming area includes a first notch corresponding to the first forming groove along the height direction of the forming cavity. The first notch is connected to the forming cavity. A first sector block is provided in the first notch. The inner arc diameter of the first sector block is the same as the diameter of the forming cavity. A second sector block is provided on the outer surface of the first sector block on the side adjacent to the upper template and the upper mold core. The first sector block protrudes from the side adjacent to the upper template and the upper mold core. The end of the second sector block away from the upper template protrudes from the first sector block.

[0012] Preferably, the third molding groove is a fan-shaped groove with its opening facing the upper mold plate, and the third molding groove is not connected to the through hole in the upper mold core. When the internal helical gear is injection molded, the inner surface of the first fan-shaped block abuts against the surface of the third molding groove near the through hole.

[0013] Preferably, the side of the upper mold core facing the upper template and the side of the lower template facing the upper template are on the same horizontal plane.

[0014] Preferably, the mounting groove is a first rectangle, a trapezoid with an upper base larger than the lower base, and a second rectangle stacked sequentially in the vertical direction; the lower surface of the first rectangle is in contact with the upper surface of the trapezoid, and the lower surface of the trapezoid is in contact with the upper surface of the second rectangle; the bottom of the mounting groove is provided with a receiving groove, which is used to receive the bearing and the base portion protruding from the bearing.

[0015] Preferably, the through hole in the upper mold core is frustum-shaped, and the diameter of the end near the upper mold core is smaller than the diameter of the end near the lower mold core. The through hole in the lower mold core is cylindrical. The base is a combination of frustum and cylinder shapes that match the through holes in the upper and lower mold cores.

[0016] Preferably, a bearing is fitted around the outer edge of the end of the base facing the lower mold core, and the outer ring of the bearing is fixedly connected to the lower mold core so that the base can rotate in the through hole.

[0017] The above-mentioned technical solutions in a helical gear injection mold provided by this utility model embodiment have at least one of the following technical effects: This utility model discloses a helical gear injection mold, which, with the cooperation of the upper mold plate's molding cavity, first molding groove, second molding groove, first molding area, and second molding area, can mold gears such as... Figure 11The external positioning and connecting parts of the internal helical gear shown are integrally injection molded with the internal helical gear structure, avoiding splicing errors and tooth shape defects caused by traditional mold split molding. At the same time, it allows the molten raw material to flow evenly along the unobstructed molding space during injection, ensuring that the raw material can fully fill the tooth cavity, end holes and other fine structures of the internal helical gear, reducing problems such as air bubbles and material shortages caused by obstructed material flow, thereby improving the integrity of the part molding, improving molding quality and reducing the defect rate.

[0018] The helical gear injection mold of this utility model can form a closed outer molding space by the abutting cooperation between the first sector block in the first molding area and the third molding groove of the upper mold core. This allows for the molding of the spiral protrusion on the outer side of the inner helical gear, avoiding dimensional deviations or structural defects on the outer side of the plastic part, and further improving the stability of the molding quality of the plastic part.

[0019] The helical gear injection mold of this utility model, with the cooperation of the molding insert, the base and the bearing, allows the molding insert to rotate flexibly around the bearing axis. During demolding, the rotation of the molding insert enables the plastic part to be smoothly released, avoiding damage to the internal teeth of the plastic part caused by forced demolding and improving molding efficiency.

[0020] The helical gear injection mold of this utility model, with its modular design of the molding mechanism, allows for quick replacement of suitable molding inserts for helical gears of different specifications, without the need to replace the entire mold, thus reducing mold idle costs and maintenance cycles, and lowering the equipment investment costs for producing multi-specification plastic parts.

[0021] The helical gear injection mold of this utility model, with the cooperation of the three-section mounting groove of the lower mold plate and the outer shape of the upper and lower mold cores, can guide the upper and lower mold cores to quickly align with the installation position, and facilitate the removal or insertion of the upper and lower mold cores from the mounting groove, simplifying the mold assembly and disassembly process and reducing the difficulty of operation for operators.

[0022] The helical gear injection mold of this utility model, with the cooperation of the frustum-shaped through hole of the upper mold core, the cylindrical through hole of the lower mold core and the base, can form radial limit and rotation guide for the base, avoid the base from deflection or shaking when rotating, ensure the coaxiality stability of the molded insert, reduce the frictional wear between the base and the inner wall of the through hole, and extend the overall service life of the mold. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 A side view of a helical gear injection mold provided for an embodiment of this utility model.

[0025] Figure 2 for Figure 1 Sectional view at point AA.

[0026] Figure 3 A perspective view of the upper template in a helical gear injection mold provided for an embodiment of this utility model.

[0027] Figure 4 for Figure 3 Enlarged view of point B in the middle.

[0028] Figure 5 A perspective view of the upper template in a helical gear injection mold provided for an embodiment of this utility model.

[0029] Figure 6 for Figure 5 A magnified view of point C in the middle.

[0030] Figure 7 A perspective view of the upper mold core in a helical gear injection mold provided for an embodiment of this utility model.

[0031] Figure 8 A perspective view of the lower mold core in a helical gear injection mold provided for an embodiment of this utility model.

[0032] Figure 9 A perspective view of the molding mechanism in a helical gear injection mold provided for an embodiment of this utility model.

[0033] Figure 10 A perspective view of the lower template in a helical gear injection mold provided for an embodiment of this utility model.

[0034] Figure 11 A perspective view of a helical gear in a helical gear injection mold provided for an embodiment of this utility model.

[0035] Figure 12 A perspective view of a helical gear in a helical gear injection mold provided for an embodiment of this utility model.

[0036] The following are the labeling elements in the figure: 10—Upper template 11—Forming cavity 12—First forming groove 13—Second forming groove 14—Injection hole; 15—Molding protrusion; 151—Molding pillar; 16—Groove 17—Boss; 18—First Molding Area; 181—First Notch 182—First sector block; 183—Second sector block; 19—Second forming area 191—Second notch 20—Upper mold core 21—Third forming groove 22—Third forming groove 30—Lower mold core; 40—Forming mechanism; 41—Forming insert; 411—Matching column 42—Base; 43—Bearing; 50—Lower template; 51—Mounting groove. Detailed Implementation

[0037] The embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the embodiments of the present invention, and should not be construed as limiting the present invention.

[0038] In the description of the embodiments of this utility model, it should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. They are only for the convenience of describing the embodiments of this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0039] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of embodiments of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0040] In this embodiment of the invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this embodiment of the invention according to the specific circumstances.

[0041] In one embodiment of this utility model, such as Figure 11As shown, the internal helical gear is a cylindrical structure with a through hole at the bottom. The teeth are distributed in a spiral shape on the inner wall of the cylinder. The forming process of the internal helical gear requires a mold to form a tooth cavity inside its cylindrical part. At the same time, some protruding structures are provided at the bottom and top of the internal helical gear for positioning, connection or cooperation with other components.

[0042] like Figure 1-2 As shown, a helical gear injection mold is provided, including an upper mold plate 10, an upper mold core 20, a lower mold core 30, a molding mechanism 40, and a lower mold plate 50. The lower mold plate 50 is the mounting base of the entire internal helical gear injection mold. The upper mold core 20 and the lower mold core 30 are arranged sequentially from top to bottom in the lower mold plate 50. The molding mechanism 40 is arranged through the upper mold core 20 and the lower mold core 30 and is rotatably connected to the bottom of the lower mold plate 50. The upper mold plate 10 is openable and closable above the lower mold plate 50. During the internal helical gear injection molding, the top surfaces of the upper mold plate 10 and the upper mold core 20 are tightly fitted together. The upper mold plate 10, the upper mold core 20, and the molding mechanism 40 together enclose a closed cavity for internal helical gear molding. The upper template 10 is the upper mold closing component of the mold. The bottom of the upper template 10 abuts against the top surface of the upper mold core 20. The shape of the upper template 10 is adapted to the upper mold core 20. The upper template 10 and its cooperation with the upper mold core 20 form the forming space for the external positioning and connecting parts of the internal helical gear. The lower template 50 is the lower base component. The mounting structure inside the lower template 50 forms a positioning support for the lower mold core 30, and at the same time provides bottom mounting and rotation limit for the forming mechanism 40. The upper mold core 20 and the lower mold core 30 are stacked on top of each other and are coaxially and abutting each other. The through holes in the upper mold core 20 and the lower mold core 30 form the installation channel of the forming mechanism 40. The cooperation between the upper mold core 20 and the lower mold core 30 realizes the stable assembly of the forming mechanism 40. The forming mechanism 40 passes through the upper mold core 20 and the lower mold core 30. The top of the forming mechanism 40 extends into the interior of the upper template 10 to form the inner hole and tooth shape of the internal helical gear. The bottom of the forming mechanism 40 is rotatably connected to the lower template 50 to realize forming and assist demolding. Through the mutual cooperation of the upper template 10, the upper mold core 20, the lower mold core 30, the forming mechanism 40 and the lower template 50, the forming deviation caused by the chaotic structure of traditional molds is avoided. The modular assembly relationship simplifies the mold disassembly and assembly process. At the same time, it ensures the coaxiality and stability of the forming mechanism when rotating for demolding, effectively improving the forming accuracy and production efficiency of the internal helical gear.

[0043] like Figure 3 , 4As shown, the upper template 10 includes a molding cavity 11, a first molding groove 12, a second molding groove 13, an injection hole 14, a molding protrusion 15, a groove 16, a boss 17, a first molding area 18, and a second molding area 19. There are two molding cavities 11, which are symmetrically arranged on the side of the upper template 10 facing the lower template 50. The molding cavity 11 is cylindrical and its opening faces the lower template 50. The molding cavity 11 provides a basic molding space for the main outline of the internal helical gear. The molding cavity 11 cooperates with the top surface of the upper mold core 20 and the top of the molding mechanism 40 to form the radial molding boundary of the internal helical gear, ensuring the dimensional accuracy of the gear body.

[0044] The first forming groove 12 and the second forming groove 13 are located at the end of the forming cavity 11 away from the upper mold core 20, that is, at the top of the forming cavity 11. The first forming groove 12 and the second forming groove 13 are evenly distributed around the axis of the forming cavity 11. There are three first forming grooves 12 and one second forming groove 13. The three first forming grooves 12 and one second forming groove 13 are arranged in a circumferential array. The first forming groove 12 is an arc-shaped groove and the second forming groove 13 is a fan-shaped groove. The second forming groove 13 is provided with a protrusion protruding from the second forming groove 13. The three first forming grooves 12 are used to form three positioning connectors of the same specification at the bottom of the internal helical gear. The one second forming groove 13 is used to form a positioning connector of another specification on the gear. The first forming grooves 12 and the second forming groove 13, through differentiated layout and quantity configuration, match the multi-positioning structure requirements of the internal helical gear and avoid the fitting problems caused by the size deviation of the positioning parts during subsequent assembly.

[0045] The injection holes 14 are provided in three evenly spaced parts that penetrate the upper template 10 and communicate with the molding cavity 11. One end of the injection hole 14 is connected to the discharge port of the injection molding machine, and the other end leads to the interior of the molding cavity 11. The injection holes 14 serve to inject molten polymer raw materials into the molding cavity 11. The distributed design of multiple injection holes 14 can balance the material filling pressure and avoid problems such as insufficient filling of cavity corners and air bubble residue caused by single injection.

[0046] The forming protrusion 15, groove 16, and boss 17 are all coaxially arranged with the forming cavity 11, and the boss 17 is located inside the forming protrusion 15. The height of the boss 17 is less than the height of the forming protrusion 15. The groove 16 forms an annular gap around the boss 17. The forming protrusion 15 is also uniformly provided with a plurality of forming pillars 151. When the mold is closed to injection mold the internal helical gear, the bottom end of the forming pillar 151 abuts against the top surface of the forming insert 41 in the forming mechanism 40. The boss 17 abuts coaxially with the mating pillar 411 at the top of the forming insert 41. The boss 17, groove 16, and forming protrusion 15 cooperate with each other to form a hole-like structure and stepped contour on the bottom end face of the internal helical gear. The coaxial abutment of the boss 17 with the mating pillar 411 at the top of the forming insert 41 further strengthens the axial positioning during molding and avoids the gear inner hole eccentricity caused by the offset of the forming insert 41.

[0047] like Figure 5 , 6 As shown, the first forming area 18 and the second forming area 19 are both located on the side adjacent to the upper template 10 and the upper mold core 20, that is, the bottom surface of the upper template 10, and the first forming area 18 and the second forming area 19 respectively correspond to the forming requirements of different structures on the outer side of the opening end of the internal helical gear.

[0048] The first forming area 18 includes a first notch 181 corresponding to the first forming groove 12 along the height direction of the forming cavity 11. The first notch 181 is in communication with the forming cavity 11, and a first sector block 182 is fixedly provided inside the notch. The inner arc diameter of the first sector block 182 is the same as the diameter of the forming cavity 11. A second sector block 183 is integrally provided on the outer surface of the upper template 10, and the first sector block 182 protrudes from the bottom surface of the upper template 10. The end of the second sector block 183 away from the upper template 10 protrudes from the first sector block 182. The cooperation of the first notch 181, the first sector block 182, and the second sector block 183 makes the internal helical gear form a connecting mechanism located outside the opening end of the internal helical gear during forming.

[0049] The structure of the second forming area 19 is basically the same as that of the first forming area 18. The difference is that the second forming area 19 is provided with a second notch 191 on the basis of the first notch 181. The second notch 191 extends along the height direction of the first notch 181. The second notch 191 serves to form a protruding positioning block at the corresponding forming position, so that the connecting part at that position on the internal helical gear has a positioning function. The extension design of the notch realizes the integral forming of the positioning block and the connecting part, without the need for subsequent secondary processing, thereby improving the overall positioning accuracy and production efficiency of the gear.

[0050] Through integrated and collaborative design, the upper template 10 completes the molding of the main outline of the internal helical gear, multi-specification positioning connectors, end hole-shaped structures, and differentiated protrusions on the outside in one go. This not only avoids the splicing errors caused by the traditional mold split molding, but also ensures sufficient material filling through the cooperation of each structure, significantly improving the molding integrity and dimensional stability of the internal helical gear.

[0051] like Figure 7 As shown, the upper mold core 20 is an intermediate forming component that adapts to the upper template 10 and the lower mold core 30. The upper mold core 20 is set in the lower template 50. The side of the upper mold core 20 facing the upper template 10 and the side of the lower template 50 facing the upper template 10 are on the same horizontal plane to ensure that the upper template 10 is subjected to uniform force when the mold is closed. The upper mold core 20 has a combination shape of cuboid and trapezoid. The end of the upper mold core 20 near the upper template 10 is cuboid and the end near the lower mold core is trapezoidal. The upper mold core 20 is provided with a through hole 21 and a third forming groove 22.

[0052] The through hole 21 is provided through the axis of the upper mold core 20 and is in the shape of a frustum. The diameter of the end facing the upper mold plate 10 is smaller than the diameter of the end near the lower mold core 30. The through hole 21 provides space for the installation of the molding mechanism 40. Its frustum-shaped structure is adapted to the frustum part of the base 42 in the molding mechanism 40. It can not only provide radial limit for the base 42 to prevent the base 42 from shifting or shaking when rotating, but also guide the base 42 to rotate stably. At the same time, it reduces the frictional wear between the base 42 and the inner wall of the through hole 21 and extends the service life of the mold.

[0053] The third molding groove 22 is located on the side of the upper mold core 20 facing the upper template 10. The third molding groove 22 is a fan-shaped groove with its opening facing the upper template 10 and does not communicate with the through hole 21. When the mold is closed to injection mold the internal helical gear, the third molding groove 22 abuts against the inner surface of the first fan-shaped block 182 and the two sides of the second fan-shaped block 183 in the first molding area 18 and the second molding area 19 of the upper template 10. The third molding groove 22 is a protrusion positioning mechanism for molding the outer side of the opening end of the internal helical gear. By cooperating with the fan-shaped block of the upper template 10, it ensures the dimensional accuracy and shape integrity of the protrusion, avoids dimensional deviations or structural defects on the outer side of the plastic part, and improves the molding quality stability of the internal helical gear.

[0054] like Figure 8As shown, the lower mold core 30 is disposed in the lower template 50 and located below the upper mold core 20. It is stacked vertically with the upper mold core 20, coaxially aligned, and abutting against it. The lower mold core 30 is a cuboid, and the lower mold core 30 and the upper mold core 20 cooperate to form the support and positioning structure of the molding mechanism 40. The lower mold core 30 has a cylindrical through hole, which is coaxially connected to the frustum-shaped through hole 21 of the lower mold core 30 and the upper mold core 20. Together, the lower mold core 30 and the upper mold core 20 form the installation channel of the molding mechanism 40. The cylindrical through hole of the lower mold core 30 is adapted to the cylindrical part of the base 42 in the molding mechanism 40 and cooperates with the frustum-shaped through hole 21 of the upper mold core 20 to achieve positioning of the base 42, ensuring that the base 42 always maintains coaxiality during rotation and avoiding out-of-tolerance of the inner hole size of the internal helical gear due to the offset of the base 42.

[0055] like Figure 9 As shown, the forming mechanism 40 is the main component for forming the inner hole and inner teeth of the internal helical gear. The forming mechanism 40 is provided through the through hole of the upper mold core 20 and the lower mold core 30. The forming mechanism 40 includes a forming insert 41, a base 42 and a bearing 43.

[0056] The molding insert 41 is disposed at one end of the base 42 facing the upper mold core 20. The molding insert 41 protrudes from the through hole 21 of the upper mold core 20. The molding insert 41 is detachably connected to the base 42 by a screw. The end of the molding insert 41 away from the lower mold core 30, that is, the top of the molding insert 41, is provided with a mating post 411.

[0057] The mating post 411 is coaxially arranged with the boss 17 of the upper template 10. When the internal helical gear is injection molded, the mating post 411 abuts against the boss 17. On the one hand, it realizes the axial positioning of the molded insert 41 and avoids the molded insert 41 from shifting due to injection pressure. On the other hand, the mating post 411 and the boss 17 work together to form a hole-like structure on the end face of the internal helical gear.

[0058] The outer surface of the molding insert 41 is provided with helical teeth that match the internal tooth profile of the internal helical gear. The part of the molding insert 41 that protrudes from the upper mold core 20 extends into the molding cavity 11 and together with the molding cavity 11 forms the internal tooth profile cavity of the internal helical gear.

[0059] The base 42 is generally shaped as a combination of a frustum and a cylinder. The base 42 is adapted to the frustum-shaped through hole 21 of the upper mold core 20 and the cylindrical through hole of the lower mold core 30, and the base 42 can rotate within the through hole. The top of the base 42 is connected to the molding insert 41, and the bottom is fitted with a bearing 43. During injection molding, the base 42 maintains the coaxiality of the molding insert 41 by adapting to the through hole. When the molded internal helical gear is removed, the base 42 drives the molding insert 41 to rotate synchronously, so that the internal teeth of the internal helical gear can be smoothly removed along the helical direction, avoiding damage to the teeth caused by forced demolding.

[0060] The bearing 43 is sleeved on the outer periphery of the end of the base 42 facing the lower mold core 30. The outer ring of the bearing 43 is fixedly connected to the lower mold core 30, and the inner ring is fixedly connected to the base 42. The bearing 43 ensures that the base 42 drives the molding insert 41 to rotate smoothly. At the same time, the fixing effect of the bearing 43 restricts the axial displacement of the base 42, preventing the molding insert 41 from axially moving during injection molding or demolding, thus ensuring the molding accuracy and demolding stability of the internal helical gear.

[0061] The structural design of the forming mechanism 40 not only realizes the forming of the inner hole and inner tooth shape of the internal helical gear, but also solves the damage problem of traditional forced demolding by rotating demolding. At the same time, the modular structural design can be quickly adapted to different specifications of internal helical gears, reducing the equipment investment cost for multi-specification production.

[0062] like Figure 10 As shown, the lower template 50 is the overall mounting base of this helical gear injection mold. The lower template 50 has a mounting groove 51 that is compatible with the upper mold core 20, the lower mold core 30, and the molding mechanism 40. The mounting groove 51 is located on the side of the lower template 50 facing the upper template 10, with its opening facing the upper template 10. The mounting groove 51 is a composite structure consisting of a first rectangle, a trapezoid with an upper base larger than the lower base, and a second rectangle stacked vertically. The lower surface of the first rectangle is flush with... The upper surface of the trapezoid fits into the mold core, and the lower surface of the trapezoid fits into the upper surface of the second rectangle. The three-section mounting groove 51 matches the shape of the upper mold core 20 and the lower mold core 30. The first rectangle and trapezoid are adapted to the upper mold core 20, and the second cuboid is adapted to the lower mold core 30, so that the upper mold core 20 and the lower mold core 30 can be quickly aligned with the installation position, simplifying the mold assembly process. At the same time, the three-section structure can form multi-directional limiting for the upper and lower mold cores, avoiding mold core displacement during mold closing and injection molding, and ensuring molding accuracy.

[0063] The bottom of the mounting groove 51 is also provided with a receiving groove, which is used to accommodate the bearing 43 and the base 42 part protruding from the bearing 43. The outer ring of the bearing 43 is fixed to the inner wall of the receiving groove. The receiving groove provides a fixed space for the bearing 43 and avoids rotation interference caused by the bottom of the base 42 being exposed, thus ensuring the compactness and stability of the overall assembly of the molding mechanism 40.

[0064] The lower mold plate 50, through the design of the mounting groove 51, provides a stable assembly base for the upper mold core 20, the lower mold core 30 and the molding mechanism 40. At the same time, the lower mold plate 50 serves as a mold base and can be fixedly connected to the injection molding machine worktable to ensure the overall stability of the entire mold during the injection molding process.

[0065] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A helical gear injection mold, characterized in that: The system includes an upper mold plate and a lower mold plate. The upper mold plate has at least one cylindrical molding cavity with its opening facing the lower mold plate. The upper mold plate has a first molding groove, a second molding groove, and molding protrusions, grooves, and bosses coaxially arranged with the molding cavity at the end of the molding cavity away from the upper mold core. The side of the upper mold plate adjacent to the upper mold core has a first molding area and a second molding area. The upper mold plate also has multiple injection holes that penetrate the molding cavity. The lower mold plate has a mounting groove corresponding to the molding cavity, with its opening facing the upper mold plate. The mounting groove contains a lower mold core, and an upper mold core is located in the mounting groove between the lower mold core and the upper mold plate. The side of the upper mold core facing the upper mold plate is provided with a third forming groove corresponding to the first forming area and the second forming area. The upper mold core and the lower mold core are coaxially provided with a through hole penetrating the upper mold core and the lower mold core. A base is rotatably provided in the through hole. A forming insert is provided at the end of the base facing the upper mold core. The forming insert protrudes from the through hole in the upper mold core. A mating post is provided at the end of the forming insert away from the lower mold core.

2. The helical gear injection mold according to claim 1, characterized in that: The boss is located in the forming protrusion and the height of the boss is less than the height of the forming protrusion, and the groove is located around the boss.

3. The helical gear injection mold according to claim 2, characterized in that: The molding protrusion is provided with molding posts, and there are multiple molding posts. When the internal helical gear is injection molded, the molding posts abut against the side of the molding insert facing the upper template.

4. The helical gear injection mold according to claim 1, characterized in that: The mating post and the boss are coaxially arranged, and when the internal helical gear is injection molded, the mating post and the boss are abutted together.

5. A helical gear injection mold according to claim 1, characterized in that: The first forming area includes a first notch corresponding to the first forming groove along the height direction of the forming cavity. The first notch is connected to the forming cavity. A first sector block is provided in the first notch. The inner arc diameter of the first sector block is the same as the diameter of the forming cavity. A second sector block is provided on the outer surface of the first sector block on the side adjacent to the upper template and the upper mold core. The first sector block protrudes from the side adjacent to the upper template and the upper mold core. The end of the second sector block away from the upper template protrudes from the first sector block.

6. A helical gear injection mold according to claim 5, characterized in that: The third molding groove is a fan-shaped groove with its opening facing the upper template, and the third molding groove does not penetrate the through hole in the upper mold core. When the internal helical gear is injection molded, the inner surface of the first fan-shaped block abuts against the surface of the third molding groove near the through hole.

7. The helical gear injection mold according to claim 1, characterized in that: The side of the upper mold core facing the upper template and the side of the lower template facing the upper template are on the same horizontal plane.

8. A helical gear injection mold according to claim 1, characterized in that: The mounting groove is composed of a first rectangle, a trapezoid with an upper base larger than its lower base, and a second rectangle stacked vertically in sequence; the lower surface of the first rectangle is in contact with the upper surface of the trapezoid, and the lower surface of the trapezoid is in contact with the upper surface of the second rectangle; the bottom of the mounting groove is provided with a receiving groove, which is used to receive the bearing and the base portion protruding from the bearing.

9. A helical gear injection mold according to claim 1, characterized in that: The through hole in the upper mold core is frustum-shaped, and the diameter of the end near the upper mold core is smaller than the diameter of the end near the lower mold core. The through hole in the lower mold core is cylindrical. The base is a combination of frustum and cylinder shapes that match the through holes in the upper and lower mold cores.

10. A helical gear injection mold according to claim 1, characterized in that: A bearing is fitted around the end of the base facing the lower mold core, and the outer ring of the bearing is fixedly connected to the lower mold core so that the base can rotate in the through hole.

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