Injection mould for a cylindrical plastic part with staggered step core pulling

Abstract

The application discloses an injection mold, which comprises an upper mold group, a lower mold group, a male mold assembly and a female mold assembly forming a cylindrical plastic part forming cavity, the male mold assembly comprises a male mold inner core and an inner core pulling mechanism, the male mold inner core forms a hollow cylinder area inside the cylindrical plastic part, the inner core pulling mechanism comprises a small inner core pulling piece, a large inner core pulling piece and a driving assembly, the small inner core pulling piece and the large inner core pulling piece enclose to form an annular main groove on the inner wall of the cylindrical plastic part, the female mold assembly comprises an outer core pulling piece and a driving assembly, and the outer core pulling piece encloses to form the outer wall of the cylindrical plastic part; when the mold is opened, the male mold inner core is first separated from the hollow cylinder area, the outer core pulling piece is horizontally outward, and the small inner core pulling piece is horizontally inward; the large inner core pulling piece drives the cylindrical plastic part to vertically lift, so that the large inner core pulling block is dislocated from the small inner core pulling block, and then the large inner core pulling piece is horizontally inward; when the mold is closed, each core pulling piece reversely slides and resets to form the forming cavity. Through the dislocation step-by-step core pulling, the injection mold can orderly pull the core inside the narrow cylindrical plastic part, and the motion interference problem of the synchronous core pulling of multiple inner core pulling pieces is avoided.

Description

Technical Field

[0001] This invention relates to the field of injection mold technology, and specifically to a cylindrical plastic part injection mold with staggered step-by-step core pulling and demolding. Background Technology

[0002] In the plastic injection molding industry, cylindrical plastic parts are widely used basic components, mainly used in assembly scenarios such as pipe fitting docking, component sleeve connection, and axial positioning and locking. They have advantages such as simple structure, convenient assembly, and strong adaptability. The plastic part has a cylindrical structure. The cylindrical plastic part 100 has a hollow cylindrical area 101 inside. The inner wall of the lower end is provided with an annular main groove 102 in the circumferential direction. The opening of the inner side of the main groove is connected to the hollow cylindrical area inside the cylindrical plastic part. Some annular main grooves have a continuous structure around the whole circumference. Some annular main grooves 102 are composed of multiple groove segments 1021 distributed in the circumferential direction. Each adjacent groove segment 1021 is separated by a wall 1022. One end of each groove segment 1021 is provided with a downward relief opening 1023. The relief opening 1023 extends downward along the axial direction of the plastic part. The inner wall of the cylindrical plastic part 100 is also provided with an annular upper groove 103 in the circumferential direction. The annular upper groove 103 has a continuous structure around the whole circumference. The opening of the lower end of the upper groove is connected to the hollow cylindrical area inside the cylindrical plastic part. The annular upper groove 103 is located on the inner side of the upper end of the annular main groove 102.

[0003] For cylindrical plastic parts with annular grooves on their inner walls, the grooves are located on the inner wall surface. Due to the overall shape of the part and the position of the grooves, conventional demolding structures such as external core pulling, angled ejection, and side parting cannot complete the molding and demolding of these grooved sections. The industry solution is to install multiple independent internal core pulling mechanisms inside the mold to individually injection mold each grooved section. After the part has cooled, all the internal core pulls retract inwards towards the center of the part, disengaging from the grooved cavity. Only then can the part be successfully ejected from the mold cavity to complete the demolding process. The internal hollow space of cylindrical plastic parts is inherently limited. The closer to the center of the plastic part, the smaller the available space for movement. The multiple sets of internal core pulls equipped with multiple groove sections can only be densely arranged in the narrow internal mold cavity. When all the internal core pulls move synchronously towards the center, as the shrinkage stroke continues to advance, the activity space of each internal core pull continues to shrink. The movement stroke and activity range of different sets of internal core pulls intertwine and overlap, which easily leads to movement interference problems such as mutual contact and squeezing between the core pull parts. This directly causes malfunctions such as movement stagnation and jamming of the internal core pull mechanism. Not only can the core pull demolding action not be completed smoothly, but the plastic parts will also have poor molding problems such as sticking to the mold and deformation, which greatly reduces the product yield and overall production efficiency. In addition, the internal core pull parts will be worn, deformed or even damaged during long-term repeated interference and collision, which greatly shortens the overall service life of the mold. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art. This invention provides a cylindrical plastic injection mold with staggered step-by-step core pulling and demolding. Through the staggered step-by-step core pulling and demolding design of the annular main groove, the core pulling action of each core pulling component can be completed in an orderly manner in the narrow internal space of the cylindrical plastic part, completely avoiding the motion interference problem when multiple internal core pulling is performed simultaneously.

[0005] The technical solution of the present invention: a cylindrical plastic injection mold for staggered step-by-step core pulling and demolding, including an upper mold assembly and a lower mold assembly, and further including a punch assembly and a die assembly that cooperate to enclose and form a cylindrical plastic molding cavity; The punch assembly includes a punch core and an inner core pulling mechanism. The punch core is used to form the hollow cylindrical area inside the cylindrical plastic part. The inner core pulling mechanism includes a small inner core pulling component, a large inner core pulling component, a small inner core pulling drive assembly for driving the small inner core pulling component to slide horizontally, a linkage lifting assembly for driving the large inner core pulling component to rise and fall vertically, and a large inner core pulling drive assembly for driving the large inner core pulling component to slide horizontally. Each of the small inner core pulling components and the large inner core pulling component are arranged circumferentially below the punch core. The small inner core pulling blocks on each small inner core pulling component and the large inner core pulling blocks on the large inner core pulling component enclose and form an annular main groove on the inner wall of the cylindrical plastic part. The cavity mold assembly includes several outer core-pulling parts and an outer core-pulling drive assembly for driving the outer core-pulling parts to slide horizontally. The several outer core-pulling parts are arranged circumferentially and are surrounded by the molding surfaces on the inner ends of each outer core-pulling part to form the outer wall of the cylindrical plastic part. During mold opening, the inner core of the punch is vertically lifted to detach from the hollow cylindrical area of ​​the plastic part. The outer core-pulling drive assembly drives the outer core-pulling component to slide horizontally outward and retract, causing the molding surface on the inner end of the outer core-pulling component to separate from the outer wall of the cylindrical plastic part for demolding. The small inner core-pulling drive assembly first drives the small inner core-pulling component to slide horizontally inward and retract, causing the small inner core-pulling blocks on each small inner core-pulling component to separate from the annular main groove on the inner wall of the cylindrical plastic part for demolding. Then, the connecting rod lifting linkage assembly drives the large inner core-pulling component to lift the injection-molded cylindrical plastic part vertically together, so that the large inner core-pulling blocks on the large inner core-pulling component and the small inner core-pulling blocks on the small inner core-pulling components form a high-low misalignment structure. Then, the large inner core-pulling drive assembly drives the large inner core-pulling component in the lifted state to slide horizontally inward and retract, causing the large inner core-pulling blocks on each large inner core-pulling component to separate from the annular main groove on the inner wall of the cylindrical plastic part for demolding. During mold closing, several external core-pulling parts, small internal core-pulling parts, and large internal core-pulling parts slide and reset in reverse order to form a cylindrical plastic part molding cavity.

[0006] Using the above technical solution, a cylindrical plastic part molding cavity is formed by enclosing the punch assembly and the die assembly. The inner core of the punch is used to mold the hollow cylindrical area inside the plastic part. Each small inner core pull part cooperates with the large inner core pull part to form the inner wall annular main groove. Each outer core pull part cooperates to form the outer wall of the plastic part. The overall structure can meet the complete molding requirements of the cylindrical plastic part with the annular inner groove.

[0007] During mold opening, the outer core-pulling component slides outward synchronously, quickly releasing the constraint of the outer wall of the plastic part, thus achieving demolding of the outer wall first; the inner core of the punch is first vertically lifted to detach from the interior of the plastic part, avoiding friction, scratches, or deformation with the inner wall of the plastic part; the small inner core-pulling component is first pulled inward, allowing the small inner core-pulling block to detach from the annular main groove in advance; then, the large inner core-pulling component, driven by the linkage lifting assembly, drives the plastic part to be vertically lifted together, so that the large inner core-pulling block and the small inner core-pulling block form a height misalignment, completely eliminating motion interference during horizontal core pulling from a spatial structure perspective; finally, the large inner core-pulling component is pulled inward in the lifted state, allowing the large inner core-pulling block to smoothly detach from the annular main groove, completing the complete inner core pulling demolding. By employing a staggered, step-by-step core-pulling method—first pulling out the smaller inner core, then raising the larger inner core, and finally pulling out the larger inner core—orderly and interference-free demolding can be achieved within the confined space inside the plastic part. This fundamentally avoids problems such as interference, jamming, and stuckness caused by the simultaneous retraction of multiple sets of inner cores, effectively preventing plastic parts from sticking to the mold, being pulled, or deformed. It significantly improves demolding stability, product molding accuracy, and production yield. When the mold is closed, each component resets in reverse order, accurately reconstructing the molding cavity and ensuring consistency in continuous production and extending the mold's lifespan.

[0008] A further provision of the present invention includes a plurality of relief port inserts for forming relief ports on the inner wall of the cylindrical plastic part. Multiple large and small inner core pullers are provided, with each small inner core puller, large inner core puller, and relief port insert arranged alternately in the circumferential direction. Each large inner core puller is equipped with a large inner core puller block, and each small inner core puller is equipped with a small inner core puller block. A unit group is formed by sequentially arranging a small inner core puller, a large inner core puller, and a relief port insert. The small inner core puller and the large inner core puller within the unit group cooperate to form a groove segment of the annular main groove. The relief port insert within the same group correspondingly forms a relief port communicating with the end of the groove segment. Furthermore, the relief port insert of any unit group is spaced apart from the small inner core puller block of another circumferentially adjacent unit group to form a wall forming cavity between adjacent groove segments.

[0009] By further configuring the above-mentioned components, and by adding a clearance insert, and arranging the small inner core-pulling components, large inner core-pulling components, and clearance inserts alternately and evenly along the circumference, the annular main groove forms a segmented molding structure. Each group of small inner core-pulling components, large inner core-pulling components, and clearance inserts corresponds to forming a groove segment and a matching clearance, realizing segmented molding and segmented core-pulling of the annular main groove. This further reduces the movement space required for a single group of core-pulling and improves the smoothness of the core-pulling action. The clearance inserts and adjacent groups of small inner core-pulling blocks are arranged alternately to form the walls between adjacent groove segments, ensuring the integrity of the inner wall structure of the plastic part. At the same time, the layout ensures that the movement trajectories of the small inner core-pulling and large inner core-pulling do not overlap or interfere with each other. Combined with the step-by-step sequence of first pulling the small inner core-pulling, then offset lifting, and then pulling the large inner core-pulling, the core-pulling actions are further guaranteed to be independent, improving the reliability of the structure. This ensures that multiple groups of inner core-pulling can smoothly complete the pulling and resetting within the narrow cylindrical cavity, improving the overall operational stability and reliability of the injection mold.

[0010] A further provision of the present invention includes an upper groove insert for forming an annular upper groove on the inner wall of a cylindrical plastic part. The clearance insert is divided into clearance insert one and clearance insert two. Clearance insert one is disposed on the small inner core pull part. The upper groove insert is connected to clearance insert two. Clearance insert two extends downward and penetrates the small inner core pull part and is linked with the connecting rod lifting linkage assembly. A clearance space is formed inside the small inner core pull part to avoid clearance insert two. The clearance space is adapted to the horizontal sliding stroke of the small inner core pull part.

[0011] By further configuring the above-mentioned components, an annular upper groove is formed on the inner wall of the plastic part by adding an upper groove insert. The relief insert is divided into relief insert one and relief insert two. Relief insert one moves synchronously with the small inner core pull component, while relief insert two is connected to the upper groove insert and passes through the small inner core pull component downwards, forming a linkage with the connecting rod lifting linkage component. The small inner core pull component has a relief space inside that is adapted to the horizontal sliding stroke. This ensures that the small inner core pull component can be freely withdrawn, while keeping relief insert two stationary in the horizontal direction, avoiding defects such as cavity size deviation, flash, and burrs caused by insert displacement. This split insert structure integrates multi-cavity molding functions in a limited space, simplifies the overall mold structure, reduces the number of parts, improves assembly accuracy and molding stability, and does not interfere with the step-by-step misalignment movement of the inner core pull component, ensuring smooth and reliable demolding.

[0012] A further provision of the present invention: the upper module includes an upper mold base and an upper mold plate; the lower module includes a lower mold base and a lower mold plate; the inner core of the punch assembly passes through the upper mold plate and is connected to the upper mold base; a small inner core puller and a large inner core puller are horizontally slidably disposed on the upper surface of the lower mold plate, and the large inner core puller can also be vertically raised and lowered relative to the lower mold plate; the outer core puller of the concave mold assembly is horizontally slidably disposed on the upper surface of the upper mold plate; the connecting rod lifting linkage assembly is disposed on the lower module; a timing mold opening assembly is provided between the upper mold plate and the lower mold plate, the timing mold opening assembly being used to limit the opening sequence of the upper mold base and the upper mold plate, so that the upper mold base opens first relative to the upper mold plate, and then the upper mold base drives the upper mold plate to open. The upper mold plate opens relative to the lower mold plate; during the initial opening stroke of the upper mold base, the inner core of the punch is vertically raised to disengage from the hollow cylindrical area of ​​the plastic part, causing the outer core-pulling drive assembly to synchronously drive the outer core-pulling component to slide outward horizontally and retract, and the small inner core-pulling drive assembly to synchronously drive the small inner core-pulling component to slide inward horizontally and retract; then the upper mold plate opens the first stroke relative to the lower mold plate to create clearance space for the large inner core-pulling component to drive the cylindrical plastic part to rise vertically; the upper mold plate opens the second stroke, causing the connecting rod lifting linkage assembly to drive the large inner core-pulling component to drive the injection-molded cylindrical plastic part to rise vertically together; the upper mold plate opens the third stroke, causing the large inner core-pulling drive assembly to drive the large inner core-pulling component in the raised state to slide inward horizontally and retract.

[0013] By further configuring the above-mentioned components, a segmented timing control is achieved through a time-sequential mold opening assembly, where the upper mold base opens first and the upper mold platen opens subsequently. This precisely binds the mold opening stroke with the core-pulling and lifting actions: the initial opening stage completes the lifting of the inner core of the punch, the outward retraction of the outer core puller, and the inward retraction of the small inner core puller; the first stage of the upper mold platen opening creates clearance space to facilitate the subsequent vertical lifting of the large inner core puller, avoiding interference with the position of the upper mold platen during the lifting process; the second stage of the upper mold platen opening triggers the linkage lifting assembly, precisely driving the large inner core puller and the plastic part to lift synchronously to complete the height misalignment; the third stage of the upper mold platen opening triggers the large inner core puller to slide inward and retract, achieving precise linkage between the mold opening stroke and the misalignment step-by-step core-pulling action. No additional complex power control components are needed; each step can be triggered sequentially simply by changes in the timing of the mold opening stroke. This simplifies the overall mold control structure, reduces mold production costs, and ensures precise timing of each action, avoiding motion interference caused by misaligned actions.

[0014] A further feature of the present invention is that each external core-pulling component is driven by a corresponding external core-pulling drive assembly. The external core-pulling drive assembly includes a sliding component A connected to the upper mold base and an oblique guide hole A opened on the outer end of the external core-pulling component. The sliding component A passes downward through the upper mold plate and has an oblique guide mating part A at its lower end. The oblique guide mating part A is inserted into the oblique guide hole A, and the oblique guide mating part A and the oblique guide hole A form an oblique sliding fit. When the sliding component A moves vertically with the upper mold base, it abuts against the oblique guide hole A through the oblique sliding fit, driving the corresponding external core-pulling component to slide in the horizontal direction.

[0015] With the above-mentioned further configuration, the external core-pulling drive assembly adopts an oblique guide mating structure between the sliding part A and the oblique guide hole A. The sliding part A moves vertically with the upper mold base. Through the oblique sliding mating part and the oblique guide hole, the vertical mold opening motion is stably converted into the horizontal retraction motion of the external core-pulling part. The transmission is direct and the synchronization is good. It can complete the demolding of the outer wall simultaneously during the opening stage of the upper mold base, without occupying the subsequent internal core-pulling sequence, thus improving the overall efficiency of mold opening. The oblique guide mating surface has high guiding accuracy and stable operation, which can ensure that the retraction stroke of the external core-pulling part is accurate and the reset is reliable. When the mold is closed, it can be smoothly locked in place, effectively avoiding defects such as scratches, burrs, and shrinkage marks on the outer wall of the plastic part.

[0016] A further feature of the present invention is that each small inner core-pulling component is driven by a corresponding small inner core-pulling driving assembly. The small inner core-pulling driving assembly includes a sliding component B fixed on the inner core of the punch and an oblique guide hole B opened on the inner end of the small inner core-pulling component. The lower end of the sliding component B has an oblique guide mating part B, which extends downward and is inserted into the oblique guide hole B, and the oblique guide mating part B and the oblique guide hole B form an oblique sliding fit. When the sliding component B moves vertically with the inner core of the punch, it abuts against the oblique guide hole B through the oblique sliding fit, driving the corresponding small inner core-pulling component to slide horizontally. The sliding components B of the plurality of small inner core-pulling driving assemblies are arranged circumferentially on the inner core of the punch.

[0017] With the above-mentioned further configuration, the small inner core pulling drive assembly adopts a sliding component B and a slanted guide hole B slanted guide fit structure. The sliding component B is fixed in the inner core of the punch and moves vertically synchronously with it. Through the inclined sliding fit between the slanted guide fit part and the slanted guide hole, the vertical lifting motion of the inner core of the punch is accurately converted into the horizontal pulling motion of the small inner core pulling component. This realizes that the inner core of the punch is removed from the cavity and the small inner core pulling is pulled out synchronously. The action is compact, the timing is reasonable, and the response is rapid. Multiple sets of sliding components B are evenly arranged in the circumferential direction. The inner core of the punch can simultaneously drive the sliding components B to lift vertically synchronously, so that multiple small inner core pulling components can be pulled out inward synchronously with consistent stroke. This avoids local jamming or incomplete pulling out, and ensures that the small inner core pulling block is completely separated from the annular main groove.

[0018] A further feature of this invention is that each of the major inner core-pulling components is driven by a corresponding major inner core-pulling drive assembly. The major inner core-pulling drive assembly includes a sliding component C connected to the upper template and a sliding seat located at the outer end of the major inner core-pulling component. The sliding seat and the major inner core-pulling component are vertically slidingly engaged via vertical guide rails and guide grooves, and the sliding seat is horizontally slidingly engaged with the lower template. The sliding seat has an oblique guide hole C. The sliding component C is vertically inserted into the lower module. The sliding component C includes an upper locking portion, a middle straight rod portion, and a lower oblique guide engagement portion C. The locking portion has a locking inclined surface on its outer side. The sliding component C is inserted into the oblique guide hole C, and the oblique guide engagement portion C and the oblique guide hole C form an inclined sliding relationship. In conjunction with the locking mechanism, the locking bevel and the inclined guide hole C also form an inclined sliding fit. When the slide member C moves with the upper template for the first and second strokes, it slides vertically within the inclined guide hole C via the straight rod to prevent the slide seat from driving the large inner core pull member to slide horizontally. When the slide member C moves with the upper template for the third stroke, the inclined guide fit C slides vertically within the inclined guide hole C. The inclined guide fit C, through the inclined sliding fit, abuts against the inclined guide hole C, driving the slide seat to drive the large inner core pull member to slide horizontally. When the mold is closed, the locking part inserts downward into the inclined guide hole C, and the locking bevel abuts against the inclined guide hole C, providing the slide seat with an outward horizontal sliding driving force, thus locking the large inner core pull member in the mold-closed position.

[0019] With the above further configuration, the inner core pulling drive assembly adopts a cooperative structure of sliding component C, sliding seat, and its upper inclined guide hole C. Vertical sliding cooperation between the inner core pulling and the sliding seat is achieved through vertical guide rails and guide grooves. The inner core pulling can be lifted vertically independently of the sliding seat, and the sliding seat can drive the inner core pulling to slide horizontally. The structural cooperation is clear, ensuring that the inner core pulling can first complete vertical lifting and then horizontal retraction, with clear layered actions that do not interfere with each other. The sliding component C is divided into a locking part, a straight rod part, and an inclined guide cooperation part. During the first and second strokes of the upper template, the straight rod part is in the inclined guide hole... The internal vertical sliding does not drive the horizontal movement of the slide seat, allowing the large internal core pull to move vertically but not horizontally. Only during the third mold opening stroke, the inclined guide mating part C engages with the inclined guide hole C, driving the slide seat to move the large internal core pull part horizontally. This perfectly matches the timing requirements of staggered step-by-step core pulling, ensuring precise triggering of the action and preventing premature or delayed core pulling, thus avoiding interference caused by premature core pulling. When the mold is closed, the locking inclined surface of the locking part presses against the wall of the inclined guide hole, pushing the slide seat outward and locking it, ensuring that the large internal core pull part remains stably in the molding position and will not shift during injection molding, thus guaranteeing the yield of the plastic part.

[0020] A further provision of the present invention: the linkage lifting assembly includes a pull rod and a cam-linkage transmission assembly. The cam-linkage transmission assembly includes a transmission plate, a linkage main shaft, and a lifting cam and a swing arm cam mounted on the linkage main shaft. The transmission plate is vertically movable inside the lower module. The linkage main shaft is rotatably mounted inside the lower module. A transmission link is hinged between the lifting cam and the transmission plate. When the linkage main shaft rotates, it drives the transmission plate to move vertically through the lifting cam and the transmission link. The transmission plate supports and connects the major inner core-pulling components circumferentially, thereby driving all the major inner core-pulling components to lift vertically synchronously. The pull rod... The upper end is fixed to the outside of the upper template, and the lower end of the pull rod is provided with a stroke groove. The swing arm cam is exposed on the outside of the lower module, and the swing arm cam is provided with a lever that extends into the stroke groove. When the upper template drives the pull rod to move upward for the first stroke, the stroke groove on the pull rod slides vertically relative to the lever until the bottom wall of the stroke groove abuts against the lever. At this time, the swing arm cam remains stationary. When the upper template drives the pull rod to continue moving upward for the second stroke, the pull rod pushes against the lever through the bottom wall of the stroke groove, thereby causing the swing arm cam to drive the linkage spindle to rotate. When the upper template drives the pull rod to continue moving upward for the third stroke, the lever of the swing arm cam disengages from the stroke groove.

[0021] With the above-mentioned further configuration, the linkage lifting assembly adopts a structure that combines a tie rod and a cam linkage transmission assembly. The segmented control of the mold opening stroke is achieved through the interaction of the tie rod's stroke groove and the rocker arm cam's actuating rod: In the first stroke segment, the cam rotation is not triggered. The length of the stroke groove meets the clearance space requirements for lifting the large inner core-pulling component. The stroke groove slides vertically relative to the actuating rod until its bottom wall just touches the actuating rod. At this point, it will not push the actuating rod to rotate, thus preventing premature triggering of the lifting action and avoiding timing errors. In the second stroke segment, the bottom wall of the tie rod pushes the actuating rod upwards, causing the rocker arm cam to rotate, which in turn drives the main shaft. The lifting cam rotates, which in turn drives the transmission plate to rise vertically via the transmission linkage. This simultaneously lifts all the large inner core-pulling parts into position, ensuring good synchronicity and stable power transmission. It can accurately complete the high-low misalignment at the preset mold opening stage without requiring additional power input, relying entirely on the mold opening stroke for drive. During the third stroke, the actuating rod disengages from the stroke slide, maintaining its position after lifting and ceasing further rotation. This does not interfere with the subsequent horizontal retraction of the large inner core-pulling parts. The overall structure is perfectly suited to the timing requirements of misaligned step-by-step core pulling, with reliable linkage and a simple structure, significantly reducing the control complexity and manufacturing cost of the mold.

[0022] A further feature of the present invention is that the lower module is also provided with a product ejection component, which is linked with the transmission plate. When the transmission plate is raised, it can drive the product ejection component to move upward synchronously. After the mold is opened, the product ejection component ejects the formed cylindrical plastic part.

[0023] By adopting the above-mentioned further settings, a product ejection component is set inside the lower module and linked with the transmission plate. When the transmission plate is raised, it can drive the product ejection component to move upward synchronously, so that the lifting of the inner core pulling and the preparatory action of the ejection system are completed simultaneously. After the mold is opened, the product can be ejected directly without additional waiting, shortening the molding cycle and improving production efficiency.

[0024] A further embodiment of the present invention: the timing mold opening assembly includes a positioning seat, a locking pin, a main control rod, and a positioning control rod. The upper end of the main control rod is fixedly connected to the side wall of the upper mold base, and the lower end is provided with a first hook. The lower end of the positioning control rod is fixedly connected to the side wall of the lower mold plate, and the upper end is provided with a second hook. The positioning seat is fixed to the side wall of the upper mold plate and is provided with a first vertical channel, a second vertical channel, and a horizontal channel. The main control rod and the positioning control rod are respectively inserted into the corresponding vertical channels. The locking pin is slidably assembled in the horizontal channel and abuts against the elastic reset member. During the initial opening stroke of the upper mold base, the locking pin engages with the positioning control rod under the action of the elastic reset member to lock the relative position of the upper and lower mold plates. The main control rod moves vertically upward with the upper mold base. When the first hook of the main control rod pushes the locking pin to overcome the elastic force and slides horizontally, the locking pin releases the engagement limit of the positioning control rod, and the upper mold base continues to move upward. At this time, the upper and lower mold plates separate, realizing segmented timing mold opening.

[0025] By further configuring the above-mentioned mechanism, the upper mold base opens first, while the upper and lower mold plates remain closed, through the engagement and limiting of the locking hook and the positioning control rod. When the main control rod moves upward to the first hook head, pushing the locking hook to overcome the elastic force and slide laterally, the locking limit is precisely released, and the upper and lower mold plates separate smoothly. This purely mechanical timing control structure requires no electrical control or complex sensing components, ensuring that the segmented mold opening sequence matches the core pulling action, avoiding collisions, interference, and damage to parts caused by timing errors, and improving the long-term stability of the mold. Attached Figure Description

[0026] Figure 1 This is a structural diagram of the cylindrical plastic part of the present invention; Figure 2 This is a cross-sectional view of the cylindrical plastic part of the present invention; Figure 3 This is a schematic diagram of the overall structure of the mold closing mechanism of the present invention; Figure 4 This is a schematic diagram of the overall structure of the mold closing mechanism of the present invention; Figure 5 This is a schematic diagram of the upper module structure of the mold of the present invention; Figure 6 This is an assembly drawing of the punch core of the mold of the present invention; Figure 7 This is a schematic diagram of the lower module structure of the mold of the present invention; Figure 8 This is a schematic diagram of the punch assembly and die assembly of the mold of the present invention; Figure 9 This is a diagram showing the mating of the outer core-pulling component and the outer core-pulling drive assembly of the mold of the present invention; Figure 10This is an exploded view of the outer core-pulling component and the outer core-pulling drive assembly of the mold of the present invention; Figure 11 This is a diagram showing the assembly of the punch core, small inner core-pulling component, and large inner core-pulling component of the mold of the present invention. Figure 12 This is a diagram showing the fit between the small inner core-pulling component and the large inner core-pulling component of the mold of the present invention; Figure 13 This is a structural diagram of a small inner core-pulling component and a large inner core-pulling component of the mold of the present invention; Figure 14 This is a diagram showing the mating of the small inner core-pulling component and the small inner core-pulling drive assembly in the mold of the present invention. Figure 15 This is an exploded view of the small inner core-pulling component and the small inner core-pulling drive assembly of the mold of the present invention; Figure 16 This is an exploded view of the inner core-pulling component and the inner core-pulling drive assembly of the mold of the present invention. Figure 17 This is a diagram showing the fit between the inner core-pulling component and the connecting rod lifting linkage assembly of the mold of the present invention. At this time, the mold is in the closed state. Figure 18 This is a diagram showing the fit between the inner core-pulling component and the connecting rod lifting linkage assembly of the mold of the present invention. At this time, the upper template is in the second stage of its upward stroke. Figure 19 This is a schematic diagram of the linkage lifting assembly structure of the mold of the present invention; Figure 20 This is a schematic diagram of the timing mold opening component structure of the mold of the present invention; Figure 21 This is a schematic diagram of the mold upper base of the present invention in the pre-opened state; Figure 22 This is a schematic diagram of the first stage of the upward stroke of the upper template of the mold according to the present invention; Figure 23 This is a schematic diagram of the second stage of the upward stroke of the upper template of the mold according to the present invention; Figure 24 This is a schematic diagram of the third stage of the upward stroke of the upper template of the mold of the present invention.

[0027] In the figure: cylindrical plastic part 100, hollow cylindrical area 101, annular main groove 102, groove section 1021, wall 1022, clearance opening 1023, annular upper groove 103; Upper module 1, lower module 2, punch core 31, upper mold base 11, upper template 12, lower mold base 21, lower template 22, punch assembly 3, die assembly 4, inner core pulling mechanism 32, small inner core pulling part 321, large inner core pulling part 322, small inner core pulling drive assembly 323, connecting rod lifting linkage assembly 324, large inner core pulling drive assembly 325, small inner core pulling block 3211, large inner core pulling block 3221, clearance space 3212, outer core pulling part 41, outer core pulling drive assembly 42, sliding part A421, oblique guide hole A422, oblique guide mating part A4211, clearance slot insert 5, clearance insert one 51, clearance insert two 52, wall forming cavity 30, upper groove insert 6, timing mold opening assembly 7, positioning seat 71, locking pin 72, main control lever 73, positioning control lever 74. First vertical channel 711, second vertical channel 712, transverse channel 713, first hook 731, second hook 741, sliding component B3231, oblique guide hole B3232, oblique guide mating part B32311, sliding component C3251, sliding seat 3252, guide rail 32521, guide groove 32522, oblique guide hole C32523, locking part 32511, straight rod part 32512, oblique guide mating part C32513, locking inclined surface 325111, pull rod 3241, stroke slide groove 32411, cam connecting rod transmission assembly 3242, transmission plate 32421, linkage spindle 32422, lifting cam 32423, swing arm cam 32424, transmission connecting rod 32425, actuating rod 324241, product ejection assembly 8. Detailed Implementation

[0028] The technical solutions in this embodiment will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] like Figure 3-24 As shown, the present invention provides a staggered step-by-step core-pulling and demolding cylindrical plastic injection mold. The overall structure can be a horizontal or vertical injection mold frame, including an upper mold assembly 1 and a lower mold assembly 2, as well as a punch assembly 3, a die assembly 4, a relief insert 5, an upper groove insert 6, a timing mold opening assembly 7, and a product ejection assembly 8. The product ejection assembly 8 is located in the lower mold assembly 2. After the mold is opened to the correct position, the product ejection assembly 8 ejects the formed cylindrical plastic part. The product ejection assembly is a conventional design and will not be described in detail here. The punch assembly 3 and the die assembly 4 cooperate to form a cylindrical plastic part molding cavity. The upper mold assembly 1 includes an upper mold base 11 and an upper mold plate 12. The lower mold assembly 2 includes a lower mold base 21 and a lower mold plate 22. A timing mold opening assembly 7 is provided between the upper mold plate 12 and the lower mold plate 22. The timing mold opening assembly 7 is used to limit the opening sequence of the upper mold base 11 and the upper mold plate 12, so that the upper mold base 11 opens relative to the upper mold plate 12 first, and then the upper mold base 11 drives the upper mold plate 12 to open relative to the lower mold plate 22. Specifically, the timing mold opening assembly 7 includes a positioning seat 71, a locking hook 72, a main control rod 73, and a positioning control rod 74. The upper end of the main control rod 73 is fixedly connected to the side wall of the upper mold base 11 by screws or pins, and the lower end is integrally provided with a first hook head 731. The lower end of the positioning control rod 74 is fixedly connected to the side wall of the lower template 22 by screws or pins, and the upper end is integrally provided with a second hook head 741. The positioning seat 71 is fixed to the side wall of the upper template 12 by screws or pins, and the positioning seat 71 is provided with... There are a first vertical channel 711, a second vertical channel 712, and a horizontal channel 713. The horizontal channel connects the first and second vertical channels. The main control rod 73 and the positioning control rod 74 are respectively inserted into the corresponding vertical channels. The locking pin 72 is slidably assembled in the horizontal channel 713 and abuts against the elastic reset member, which is a spring. During the initial opening stroke of the upper mold base 11, the locking pin 72 engages with the positioning control rod 74 under the action of the elastic reset member to lock the upper mold base 1. 2. The relative position of the main control rod 73 with the lower template 22 is such that the main control rod 73 moves vertically upward with the upper mold base 11. When the first hook 731 of the main control rod 73 pushes the locking hook 72 to overcome the elastic force and slides laterally, the locking hook 72 releases the hook limit of the positioning control rod 74, and the upper mold base 11 continues to move upward. At this time, the upper template 12 and the lower template 22 are separated, realizing segmented sequential mold opening. The main control rod 73 and the positioning control rod 74 are conventional designs, and their hook end faces can be designed as inclined surfaces that are easy to insert into the vertical channel. Specifically, the punch assembly 3 includes a punch inner core 31 and an inner core pulling mechanism 32. The punch inner core 31 passes through the upper template 12 and is connected to the upper mold base 11 by screws or pins. The punch inner core 31 is used to form the hollow cylindrical area inside the cylindrical plastic part. The inner core pulling mechanism 32 includes a small inner core pulling component 321, a large inner core pulling component 322, a small inner core pulling drive assembly 323 for driving the small inner core pulling component 321 to slide horizontally, a linkage lifting assembly 324 for driving the large inner core pulling component 322 to rise and fall vertically, and a mechanism for driving the large inner core pulling component 322 to slide horizontally. The large inner core pulling drive assembly 325, the small inner core pulling parts 321 and the large inner core pulling parts 322 are arranged circumferentially below the inner core of the punch 31, and the small inner core pulling blocks 3211 on each small inner core pulling part 321 and the large inner core pulling blocks 3221 on each large inner core pulling part 322 form an annular main groove on the inner wall of the cylindrical plastic part. The small inner core pulling parts 321 and the large inner core pulling parts 322 can be horizontally slidably disposed on the upper surface of the lower template 22, and the large inner core pulling parts 322 can also be vertically raised and lowered relative to the lower template 22. The linkage lifting assembly 324 is disposed on the lower module 2. Multiple small internal core-pulling components 321 are provided, and each small internal core-pulling component 321 is driven by a corresponding small internal core-pulling driving assembly 323. The small internal core-pulling driving assembly 323 includes a sliding component B3231 fixed on the inner core 31 of the punch and an oblique guide hole B3232 opened on the inner end of the small internal core-pulling component 321. The sliding components B3231 of the multiple small internal core-pulling driving assemblies 323 are arranged circumferentially on the inner core 31 of the punch. The sliding components B3231 are fixed to the inner core of the punch with screws or abutted and positioned after vertical sliding assembly. The lower end of the sliding component B3231 is integrally provided with an oblique guide mating part B32311. 2311 extends downward and is inserted into the inclined guide hole B3232. The inclined guide mating part B32311 and the inclined guide hole B3232 form an inclined sliding fit. When the inner core of the punch moves upward with the upper mold base to open the mold, the sliding part B3231 moves vertically with the inner core of the punch 31. The inclined guide mating part B moves upward synchronously. Through the abutment fit between the inclined surface and the inclined guide hole B, the small inner core pulling part slides horizontally towards the center of the inner core of the punch, so that the small inner core pulling block is pulled out from the corresponding position of the annular main groove in advance, completing the first step of core pulling action, making way for the subsequent lifting of the large inner core pulling part, and avoiding positional interference with the adjacent large inner core pulling block. Multiple large inner core-pulling components are provided, and each large inner core-pulling component 322 is driven by a corresponding large inner core-pulling drive assembly 325. The large inner core-pulling drive assembly 325 includes a sliding component C3251 connected to the upper template 12 by screws or bolts and a sliding seat 3252 located at the outer end of the large inner core-pulling component 322. The sliding seat 3252 and the large inner core-pulling component 322 form a vertical sliding fit through a vertical guide rail 32521 and a guide groove 32522, and the sliding seat 3252 forms a horizontal sliding fit with the lower template 22. A slanted guide hole C32523 is provided on the 252. The sliding member C3251 is vertically inserted into the lower module 2. The sliding member C3251 includes an upper locking part 32511, a middle straight rod part 32512, and a lower slanted guide mating part C32513. The locking part 32511, the straight rod part 32512, and the slanted guide mating part C32513 are integrally formed. The locking part 32511 has a locking inclined surface 325111 on its outer side. The sliding member C3251 is inserted into the slanted guide hole C32523, and the slanted guide mating part... C32513 and the inclined guide hole C32523 form an inclined sliding fit. The locking inclined surface 325111 of the locking part 32511 and the inclined guide hole C32523 also form an inclined sliding fit. When the sliding part C3251 moves with the upper template 12 for the first and second strokes, it slides vertically in the inclined guide hole C32523 through the straight rod part 32512, which will not cause the sliding seat to move horizontally. After the small inner core is pulled out and the large inner core is lifted into place to complete the misalignment avoidance, the sliding part C continues to move upward with the upper template for the third stroke. The inclined guide mating part C32513 slides vertically within the inclined guide hole C32523. Through the inclined sliding fit, the inclined guide mating part C32513 abuts against the inclined guide hole C32523, driving the slide seat 3252 to move the large inner core pull part 322 horizontally. When the mold is closed, the locking part 32511 inserts downward into the inclined guide hole C32523. Through the locking inclined surface 325111 abutting against the inclined guide hole C32523, it provides the slide seat 3252 with an outward horizontal sliding driving force, locking the large inner core pull part 322 in the mold closed position. The linkage lifting assembly 324 includes a pull rod 3241 and a cam-linkage transmission assembly 3242. The cam-linkage transmission assembly 3242 includes a transmission plate 32421, a linkage main shaft 32422, and a lifting cam 32423 and a swing arm cam 32424 mounted on the linkage main shaft 32422. The lifting cam 32423 and the swing arm cam 32424 are fixed or integrally mounted on the linkage main shaft. The transmission plate 32421 is vertically movable inside the lower module 2. The linkage main shaft 32422 is rotatably mounted via bearings. Inside the lower module 2, a transmission link 32425 is hinged between the lifting cam 32423 and the transmission plate 32421. When the linkage spindle 32422 rotates, the lifting cam 32423 and the transmission link 32425 drive the transmission plate 32421 to move vertically. The transmission plate 32421 supports and connects the large inner core-pulling components 322 circumferentially, thereby driving all the large inner core-pulling components 322 to lift vertically synchronously. The product ejection assembly 8 is linked with the transmission plate 32421. When the transmission plate 32421 is lifted, it can drive the product ejection assembly 8 to lift vertically. The ejector assembly 8 moves upward synchronously; the upper end of the pull rod 3241 is fixed to the outside of the upper template 12 by screws or pins, and the lower end of the pull rod 3241 is provided with a stroke groove 32411; the swing arm cam 32424 is exposed on the outside of the lower module 2, and the swing arm cam 32424 is provided with a lever 324241 that extends into the stroke groove 32411; when the upper template 12 drives the pull rod 3241 to move upward for the first stroke, the stroke groove 32411 on the pull rod 3241 slides vertically relative to the lever 324241 until the stroke groove 32411 moves upward. The bottom wall of 411 is exactly against the actuating rod 324241, at which time the rocker arm cam 32424 remains stationary; when the upper template 12 drives the pull rod 3241 to continue moving upward for the second stroke, the pull rod 3241 pushes the actuating rod 324241 through the bottom wall of the stroke slide groove 32411, causing the rocker arm cam 32424 to rotate, thereby driving the linkage spindle 32422 to rotate; when the upper template 12 drives the pull rod 3241 to continue moving upward for the third stroke, the actuating rod 324241 of the rocker arm cam 32424 disengages from the stroke slide groove 32411. Specifically, the cavity mold assembly 4 includes a plurality of outer core-pulling components 41 and an outer core-pulling drive assembly 42 for driving the outer core-pulling components 41 to slide horizontally. The plurality of outer core-pulling components 41 are arranged circumferentially and are horizontally slidably disposed on the upper surface of the upper mold plate 12. The molding surfaces on the inner ends of each outer core-pulling component 41 enclose the outer wall of the cylindrical plastic part. Each outer core-pulling component 41 is horizontally slidably disposed on the upper surface of the upper mold plate 12 and is driven by a corresponding outer core-pulling drive assembly 42. The outer core-pulling drive assembly 42 includes a row of screws connected to the upper mold base 11. The positioning component A421 and the inclined guide hole A422 are opened on the outer end of the outer core-pulling component 41. The positioning component A421 passes downward through the upper template 12 and has an inclined guide fitting part A4211 at its lower end. The inclined guide fitting part A4211 is inserted into the inclined guide hole A422, and the inclined guide fitting part A4211 and the inclined guide hole A422 form an inclined sliding fit. When the positioning component A421 moves vertically with the upper mold base 11, the inclined guide fitting part A4211 abuts against the inclined guide hole A422 through the inclined sliding fit, driving the corresponding outer core-pulling component 41 to slide in the horizontal direction. When the mold is opened, the upper mold base 11 opens first, causing the inner core of the punch 31 to be vertically lifted to separate from the hollow cylindrical area of ​​the plastic part. This causes the sliding part A of the outer core pulling drive assembly 42 to move upward synchronously, driving each outer core pulling part to slide horizontally outward synchronously and pull out, completing the demolding and core pulling of the outer wall of the cylindrical plastic part. At the same time, the inner core of the punch drives the sliding part B of the small inner core pulling drive assembly to move upward synchronously. Through the inclined sliding fit between the inclined guide part B and the inclined guide hole B, each small inner core pulling part is driven to slide horizontally inward, causing the small inner core pulling block to be pulled out from the corresponding position of the annular main groove, completing the first step of inner core pulling. After the above actions are completed, the upper mold base has completed the initial mold opening stroke. At this time, the locking pin is pushed laterally by the first hook of the main control rod, releasing the locking of the positioning control rod, and the upper mold plate moves upward relative to the lower mold plate. During the first stroke of the upper template, the bottom wall of the travel groove on the pull rod just abuts against the actuating rod. The rocker arm cam remains stationary, the main shaft does not rotate, and all the large inner core-pulling components remain in their original positions without lifting. When the pull rod continues to move upward with the upper template to the second stroke, the pull rod drives the actuating rod to move through the bottom wall of the travel groove, causing the rocker arm cam to rotate around the axis of the main shaft. After the main shaft rotates synchronously, it drives the transmission linkage through the lifting cam, pushing the transmission plate to lift vertically as a whole. The transmission plate simultaneously supports and drives all the large inner core-pulling components to lift synchronously along the circumference. The upper platen is lifted so that the large inner core-pulling block is misaligned with the small inner core-pulling block after it has been removed, thus preventing further interference during core pulling. When the pull rod moves upward with the upper platen to the third stroke, the actuating rod disengages from the stroke groove. At this time, the sliding component C continues to move upward with the upper platen, and the inclined guide part C and the inclined guide hole C form an inclined sliding fit, driving the sliding seat to slide inward in the horizontal direction. This causes the large inner core-pulling block, which has been raised to the position, to be simultaneously pulled out horizontally inward, completing the second step of the inner core pulling action. Finally, the product ejection component moves upward synchronously with the transmission plate, ejecting the molded cylindrical plastic part and demolding it. When the mold is closed, several outer core-pulling parts 41, small inner core-pulling parts 321 and large inner core-pulling parts 322 slide and reset in reverse order to form a cylindrical plastic part molding cavity.

[0030] The aforementioned oblique guide holes and oblique guide mating parts are all conventional designs, as disclosed in patent documents such as CN121157306B and CN121798858A. The oblique guide mating part can be an oblique guide post or a T-shaped oblique guide block, and the oblique guide hole is a matching oblique post hole or a T-shaped oblique guide hole structure. By setting the oblique guide mating part and the oblique guide hole to be inclined inward from top to bottom, when the mold is opened, the oblique guide mating part is vertically displaced by the upward movement of the upper mold, which can drive the corresponding core-pulling part to slide horizontally inward. This structure does not require additional power and can automatically complete the core pulling by relying on the mold opening power. The specific structure of this solution will not be described in detail here.

[0031] Specifically, it also includes several relief port inserts 5 for molding relief ports on the inner wall of cylindrical plastic parts and upper groove inserts 6 for molding annular upper grooves on the inner wall of cylindrical plastic parts. Small inner core pullers 321, large inner core pullers 322, and relief port inserts 5 are arranged alternately circumferentially. Each large inner core puller 322 is fixedly or integrally provided with a large inner core puller block 3221, and each small inner core puller 321 is fixedly or integrally provided with a small inner core puller block 3211. A unit group is formed by sequentially arranging a small inner core puller 321, a large inner core puller 322, and a relief port insert 5. Within a unit group, the small inner core puller 321 and the large inner core puller 322 cooperate to mold a groove segment of the annular main groove. The relief port inserts 5 within the same group correspondingly form a relief port communicating with the end of the groove segment. Furthermore, any unit group... The clearance insert 5 is spaced apart from the small inner core block 3211 of another unit group in the circumferential direction to form the wall forming cavity 30 between adjacent groove segments; the clearance insert 5 is divided into clearance insert one 51 and clearance insert two 52. The clearance insert one 51 is provided on the small inner core block 321. The upper groove insert 6 is integrally connected with the clearance insert two 52. The clearance insert two 52 extends downward and penetrates the small inner core block 321, and is linked with the linkage lifting assembly 324. The clearance insert two 52 is connected to the transmission plate by screws or pins. The transmission plate drives the clearance insert two to be lifted vertically together. The small inner core block 3211 forms a clearance space 3212 to avoid the clearance insert two 52. The clearance space 3212 is adapted to the horizontal sliding stroke of the small inner core block 321.

[0032] The detailed working principle is as follows: After the mold is closed, molten plastic is injected into the cylindrical plastic part molding cavity, and cooled and molded to obtain a cylindrical plastic part with an annular inner wall groove; When the mold opens, the upper mold base moves upward with the injection molding machine. The timing mold opening assembly keeps the upper and lower mold plates locked. At this time, the upper mold base drives the inner core of the punch, slide member A, and slide member B to move upward synchronously. During the upward movement of slide member A, through the inclined engagement of the inclined guide part A and the inclined guide hole A, all the outer core-pulling parts are driven to slide outward horizontally and be pulled away synchronously, completing the demolding of the outer wall of the cylindrical plastic part. During the upward movement of slide member B, through the inclined engagement of the inclined guide part B and the inclined guide hole B, all the small inner core-pulling parts are driven to slide inward horizontally and be pulled away synchronously, so that the small inner core-pulling blocks are pulled away from the corresponding positions of the annular main groove, completing the first step of inner wall core pulling, making way for the subsequent lifting of the large inner core-pulling parts. After the upper mold base completes the aforementioned initial mold opening stroke, the first hook of the main control rod pushes the locking pin to slide laterally, releasing the locking pin from locking the positioning control rod. The upper mold plate moves upward with the upper mold base, beginning the mold opening stroke relative to the lower mold plate. During the upward movement of the upper mold plate, it drives the pull rod and the sliding component C to move upward synchronously. In the first segment of the stroke, the stroke groove slides vertically relative to the actuating rod. The bottom wall of the stroke groove just abuts against the actuating rod without pushing it. The rocker arm cam remains stationary, and the positions of the major internal core-pulling components remain unchanged. No lifting action will occur. At this time, the straight rod part of the sliding component C slides vertically within the inclined guide hole C. The straight rod part is a vertical straight rod structure and will not form a driving engagement with the inclined guide hole C. Therefore, the sliding seat will not cause the large inner core pulling component to move horizontally, keeping the large inner core pulling component in its original position and waiting for lifting. The upper template continues to move upward into the second stroke. The bottom wall of the stroke groove pushes the actuating rod upward, causing the swing arm cam to rotate around the axis of the linkage main shaft. After the linkage main shaft rotates synchronously, it drives the transmission connecting rod to move through the lifting cam, pushing... The transmission plate is raised vertically as a whole, which drives all the large inner core-pulling components to rise vertically simultaneously. This raises the large inner core-pulling blocks to the misaligned position of the smaller inner core-pulling blocks that have already been removed, completely avoiding positional interference from the smaller inner core-pulling blocks. The product ejection assembly also rises vertically synchronously with the transmission plate. At this time, the straight rod of the sliding component C continues to slide vertically within the oblique guide hole C, without forming a driving engagement with the oblique guide hole C. The sliding seat will not cause the large inner core-pulling components to undergo horizontal displacement. When entering the third stage of the stroke, the actuating rod and the stroke... The sliding groove disengages, completing the lifting action. At this point, the sliding component C also moves upward to the position where the inclined guide fitting C and the inclined guide hole C form an inclined sliding fit. As it continues to move upward, the inclined surface abuts against the sliding seat, causing the large inner core-pulling component to slide horizontally inward. This allows the large inner core-pulling block, which has been lifted into position, to be pulled out from the corresponding position in the annular main groove, completing the second step of inner wall core pulling. Afterward, the upper mold base and upper mold plate continue to move upward to open the mold. The product ejection assembly ejects the formed cylindrical plastic part from the punch as a whole, completing the entire demolding and core pulling process. Because the clearance opening on the cylindrical plastic part and the opening of the annular upper groove face downward, the cylindrical plastic part can be ejected directly by the product ejection assembly in one go without interference from the corresponding insert structure.

[0033] When the mold is closed, the upper mold base moves downward, and each component moves in reverse according to the mold opening sequence. The sliding component C first pushes the sliding base to drive the large inner core pull component to reset outward. The transmission plate drives the large inner core pull component to descend and reset. Then the small inner core pull component resets outward, and the outer core pull component resets inward. Finally, all the core pull components surround to form a complete cylindrical plastic part molding cavity, waiting for the next injection molding.

[0034] It should be noted that in the description of this invention, all directional indications such as up, down, forward, backward, etc. are only used to explain the relative positional relationship and movement of the components in a specific posture as shown in the accompanying drawings. If the specific posture changes, the directional indication will also change accordingly.

[0035] Furthermore, in this invention, the use of terms such as "first," "second," etc., is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. In the description of this invention, "a number" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0036] In the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," "fixing," and "fixing" 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 invention based on the specific circumstances.

Claims

1. A cylindrical plastic injection mold for staggered, step-by-step core-pulling demolding, comprising an upper mold assembly (1) and a lower mold assembly (2), characterized in that: It also includes a punch assembly (3) and a die assembly (4) that cooperate to enclose and form a cylindrical plastic part molding cavity; The punch assembly (3) includes a punch core (31) and an inner core pulling mechanism (32). The punch core (31) is used to form the hollow cylindrical area inside the cylindrical plastic part. The inner core pulling mechanism (32) includes a small inner core pulling component (321), a large inner core pulling component (322), a small inner core pulling drive assembly (323) for driving the small inner core pulling component (321) to slide horizontally, and a connecting rod lifting assembly for driving the large inner core pulling component (322) to rise and fall vertically. The moving assembly (324) and the large inner core pulling drive assembly (325) that drives the large inner core pulling component (322) to slide horizontally, the small inner core pulling components (321) and the large inner core pulling component (322) are arranged circumferentially below the inner core of the punch (31), and the small inner core pulling blocks (3211) on each small inner core pulling component (321) and the large inner core pulling blocks (3221) on the large inner core pulling component (322) form the annular main groove on the inner wall of the cylindrical plastic part; The cavity mold assembly (4) includes a plurality of outer core-pulling parts (41) and an outer core-pulling drive assembly (42) for driving the outer core-pulling parts (41) to slide horizontally. The plurality of outer core-pulling parts (41) are arranged circumferentially and are surrounded by the molding surfaces on the inner ends of each outer core-pulling part (41) to form the outer wall of the cylindrical plastic part. When the mold is opened, the inner core (31) of the punch is lifted vertically to detach from the hollow cylindrical area of ​​the plastic part. The outer core pulling drive assembly (42) drives the outer core pulling part (41) to slide outward horizontally and retract, so that the molding surface on the inner end of the outer core pulling part (41) separates from the outer wall of the cylindrical plastic part and demolds it. The small inner core pulling drive assembly (323) first drives the small inner core pulling part (321) to slide inward horizontally and retract, so that the small inner core pulling block (3211) on each small inner core pulling part (321) separates from the annular main groove on the inner wall of the cylindrical plastic part and demolds it. Then the connecting rod lifts in linkage. The component (324) drives the large inner core pull component (322) to lift the injection-molded cylindrical plastic part vertically together, so that the large inner core pull block (3221) on the large inner core pull component (322) and the small inner core pull block (3211) on the small inner core pull component (321) form a high-low misalignment structure. Then, the large inner core pull drive component (325) drives the large inner core pull component (322) in the lifted state to slide and retract horizontally inward, so that the large inner core pull block (3221) on the large inner core pull component (322) separates from the annular main groove on the inner wall of the cylindrical plastic part and demolds it. When the mold is closed, several outer core-pulling parts (41), small inner core-pulling parts (321) and large inner core-pulling parts (322) slide and reset in reverse order to form a cylindrical plastic part molding cavity.

2. The cylindrical plastic injection mold for staggered step-by-step core pulling and demolding according to claim 1, characterized in that: It also includes several relief inserts (5) for the relief openings on the inner wall of the molded cylindrical plastic parts. Multiple large inner core pullers (322) and small inner core pullers (321) are provided. Each small inner core puller (321), large inner core puller (322), and relief insert (5) are arranged alternately in the circumferential direction. Each large inner core puller (322) is equipped with a large inner core puller block (3221), and each small inner core puller (321) is equipped with a small inner core puller block (3211). A series of small inner core pullers (321) are arranged in sequence. A unit group consists of a large inner core puller (322) and a relief port insert (5). The small inner core puller (321) in the unit group cooperates with the large inner core puller (322) to form a groove segment of the annular main groove. The relief port insert (5) in the same group forms a relief port that communicates with the end of the groove segment. The relief port insert (5) of any unit group is spaced apart from the small inner core puller block (3211) of another unit group in the circumferential direction to form the wall forming cavity (30) between adjacent groove segments.

3. The cylindrical plastic injection mold for staggered step-by-step core pulling and demolding according to claim 2, characterized in that: It also includes an upper groove insert (6) for forming an annular upper groove on the inner wall of a cylindrical plastic part. The relief insert (5) is divided into relief insert one (51) and relief insert two (52). The relief insert one (51) is located on the small inner core pull member (321). The upper groove insert (6) is connected to the relief insert two (52). The relief insert two (52) extends downward and penetrates the small inner core pull member (321) and is linked with the linkage lifting assembly (324). The small inner core pull member (321) forms a relief space (3212) to avoid the relief insert two (52). The relief space (3212) is adapted to the horizontal sliding stroke of the small inner core pull member (321).

4. The cylindrical plastic injection mold for staggered step-by-step core pulling and demolding according to claim 1, 2, or 3, characterized in that: The upper module (1) includes an upper mold base (11) and an upper template (12), and the lower module (2) includes a lower mold base (21) and a lower template (22). The punch core (31) of the punch assembly passes through the upper template (12) and is connected to the upper mold base (11). The small inner core puller (321) and the large inner core puller (322) are horizontally slidably disposed on the upper surface of the lower template (22), and the large inner core puller (322) can also be vertically aligned with the lower template (22). The outer core-pulling component (41) of the cavity mold assembly is horizontally slidably disposed on the upper surface of the upper template (12), and the connecting rod lifting linkage assembly (324) is disposed on the lower mold assembly (2); a timing mold opening assembly (7) is provided between the upper template (12) and the lower template (22), and the timing mold opening assembly (7) is used to limit the mold opening sequence of the upper mold base (11) and the upper template (12), so that the upper mold base (11) opens first relative to the upper template (12), and then... The upper mold base (11) drives the upper template (12) to open relative to the lower template (22); during the initial opening stroke of the upper mold base (11), the inner core of the punch (31) is vertically raised to disengage from the hollow cylinder area of ​​the plastic part, causing the outer core pulling drive assembly (42) to synchronously drive the outer core pulling part (41) to slide outward horizontally and retract, and causing the small inner core pulling drive assembly (323) to synchronously drive the small inner core pulling part (321) to slide inward horizontally and retract; subsequently, the upper template (12) opens relative to the lower template (22). 2) Start the first stroke to make room for the large inner core puller (322) to lift the cylindrical plastic part vertically; the upper template (12) starts the second stroke, so that the connecting rod lifting linkage assembly (324) drives the large inner core puller (322) to lift the injection-molded cylindrical plastic part vertically together; the upper template (12) starts the third stroke, so that the large inner core puller drive assembly (325) drives the large inner core puller (322) in the lifted state to slide and retract horizontally inward.

5. The cylindrical plastic injection mold for staggered step-by-step core pulling and demolding according to claim 4, characterized in that: Each external core-pulling component (41) is driven by a corresponding external core-pulling drive assembly (42). The external core-pulling drive assembly (42) includes a sliding component A (421) connected to the upper mold base (11) and an oblique guide hole A (422) opened on the outer end of the external core-pulling component (41). The sliding component A (421) passes downward through the upper mold plate (12) and has an oblique guide mating part A (4211) at its lower end. The oblique guide mating part A (4211) is inserted into the oblique guide hole A (422), and the oblique guide mating part A (4211) and the oblique guide hole A (422) form an oblique sliding fit. When the sliding component A (421) moves vertically with the upper mold base (11), the oblique guide mating part A (4211) abuts against the oblique guide hole A (422) through the oblique sliding fit, driving the corresponding external core-pulling component (41) to slide in the horizontal direction.

6. The cylindrical plastic injection mold for staggered step-by-step core pulling and demolding according to claim 4, characterized in that: Each small inner core-pulling component (321) is driven by a corresponding small inner core-pulling drive assembly (323). The small inner core-pulling drive assembly (323) includes a sliding component B (3231) fixed on the inner core of the punch (31) and an oblique guide hole B (3232) opened on the inner end of the small inner core-pulling component (321). The lower end of the sliding component B (3231) has an oblique guide mating part B (32311). The oblique guide mating part B (32311) 11) It extends downward and is inserted into the inclined guide hole B (3232), and the inclined guide fitting part B (32311) and the inclined guide hole B (3232) form an inclined sliding fit; when the sliding part B (3231) moves vertically with the inner core of the punch (31), the inclined guide fitting part B (32311) abuts against the inclined guide hole B (3232) through the inclined sliding fit, driving the corresponding small inner core pulling part (321) to slide in the horizontal direction; The sliding parts B (3231) of several small inner core pulling drive components (323) are arranged circumferentially on the inner core (31) of the punch.

7. The cylindrical plastic injection mold for staggered step-by-step core pulling and demolding according to claim 4, characterized in that: Each of the major inner core-pulling components (322) is driven by a corresponding major inner core-pulling drive assembly (325). The major inner core-pulling drive assembly (325) includes a sliding component C (3251) connected to the upper template (12) and a sliding seat (3252) located at the outer end of the major inner core-pulling component (322). The sliding seat (3252) and the major inner core-pulling component (322) are vertically slidingly engaged through a vertical guide rail (32521) and a guide groove (32522). The sliding seat (3252) and the lower template (22) are horizontally slidingly engaged. 2) An oblique guide hole C (32523) is provided on the upper part. The sliding member C (3251) is vertically inserted into the lower module (2). The sliding member C (3251) includes a locking part (32511) at the upper end, a straight rod part (32512) in the middle, and an oblique guide mating part C (32513) at the lower end. The locking part (32511) has a locking inclined surface (325111) on the outside. The sliding member C (3251) is inserted into the oblique guide hole C (32523), and the oblique guide mating part C (32513) and the oblique guide hole C (32523) form an inclined plane. The inclined sliding fit is formed by the locking inclined surface (325111) of the locking part (32511) and the inclined guide hole C (32523). When the sliding member C (3251) moves with the upper template (12) for the first and second strokes, it slides vertically in the inclined guide hole C (32523) through the straight rod part (32512) to avoid driving the sliding seat (3252) to drive the large inner core puller (322) to slide horizontally. When the sliding member C (3251) moves with the upper template (12) for the third stroke, the inclined guide fit part C (32513) is in The inclined guide hole C (32523) slides vertically. The inclined guide fitting part C (32513) with inclined sliding fit abuts against the inclined guide hole C (32523), driving the slide seat (3252) to drive the large inner core pull part (322) to slide horizontally. When the mold is closed, the locking part (32511) is inserted downward into the inclined guide hole C (32523). The locking inclined surface (325111) abuts against the inclined guide hole C (32523), providing the slide seat (3252) with an outward horizontal sliding driving force, so that the large inner core pull part (322) is locked in the mold closed position.

8. The cylindrical plastic injection mold for staggered step-by-step core pulling and demolding according to claim 7, characterized in that: The linkage lifting assembly (324) includes a pull rod (3241) and a cam linkage transmission assembly (3242). The cam linkage transmission assembly (3242) includes a transmission plate (32421), a linkage main shaft (32422), and a lifting cam (32423) and a swing arm cam (32424) mounted on the linkage main shaft (32422). The transmission plate (32421) is vertically movable inside the lower module (2), and the linkage main shaft (32422) is rotatably mounted inside the lower module (2). A transmission link (32425) is hinged between the cam (32423) and the transmission plate (32421). When the linkage spindle (32422) rotates, it lifts the cam (32423) and the transmission link (32425) to drive the transmission plate (32421) to move vertically. The transmission plate (32421) supports and connects the large inner core-pulling components (322) circumferentially, thereby driving all the large inner core-pulling components (322) to lift vertically synchronously. The upper end of the pull rod (3241) is fixed to the outside of the upper template (12). 41) A travel groove (32411) is provided at the lower end. The swing arm cam (32424) is exposed outside the lower module (2). The swing arm cam (32424) is provided with a lever (324241) that extends into the travel groove (32411). When the upper template (12) drives the pull rod (3241) to move upward for the first stroke, the travel groove (32411) on the pull rod (3241) slides vertically relative to the lever (324241) until the bottom wall of the travel groove (32411) abuts against the lever (324241). When the upper template (12) drives the pull rod (3241) to continue moving upward for the second stroke, the pull rod (3241) pushes the actuating rod (324241) through the bottom wall of the stroke groove (32411), thereby causing the swing arm cam (32424) to drive the linkage spindle (32422) to rotate; when the upper template (12) drives the pull rod (3241) to continue moving upward for the third stroke, the actuating rod (324241) of the swing arm cam (32424) disengages from the stroke groove (32411).

9. The cylindrical plastic injection mold for staggered step-by-step core pulling and demolding according to claim 8, characterized in that: The lower module (2) is also provided with a product ejection assembly (8). The product ejection assembly (8) is linked with the transmission plate (32421). When the transmission plate (32421) is raised, it can drive the product ejection assembly (8) to move upward synchronously. After the mold is opened, the product ejection assembly (8) ejects the formed cylindrical plastic part.

10. The cylindrical plastic injection mold for staggered step-by-step core pulling and demolding according to claim 4, characterized in that: The timing mold opening assembly (7) includes a positioning seat (71), a locking hook (72), a main control rod (73), and a positioning control rod (74). The upper end of the main control rod (73) is fixedly connected to the side wall of the upper mold base (11), and the lower end is provided with a first hook (731). The lower end of the positioning control rod (74) is fixedly connected to the side wall of the lower template (22), and the upper end is provided with a second hook (741). The positioning seat (71) is fixed to the side wall of the upper template (12). The positioning seat (71) is provided with a first vertical channel (711), a second vertical channel (712), and a horizontal channel (713). The main control rod (73) and the positioning control rod (74) are respectively inserted into the corresponding vertical channels. The locking pin (72) slides and is fitted in the transverse channel (713) and abuts against the elastic reset member. During the initial opening stroke of the upper mold base (11), the locking pin (72) engages with the positioning control rod (74) under the action of the elastic reset member to lock the relative position of the upper template (12) and the lower template (22). The main control rod (73) moves vertically upward with the upper mold base (11). When the first hook head (731) of the main control rod (73) pushes the locking pin (72) to overcome the elastic force and slides laterally, the locking pin (72) releases the engagement limit of the positioning control rod (74). The upper mold base (11) continues to move upward. At this time, the upper template (12) and the lower template (22) separate, realizing segmented sequential mold opening.

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