A tubular insert injection mold

Abstract

This application relates to the technical field of molding materials in a plastic state, and provides a tubular insert injection mold, including a mold body with a cavity for accommodating the insert, a positioning block and an internal support mechanism. The positioning block has a positioning hole, and one end of the insert is detachably connected to the positioning hole. One end of the mold cavity has a positioning groove for the positioning block to fit into. The internal support mechanism includes a first internal support rod and a second internal support rod arranged opposite to each other. The first internal support rod is slidably disposed at the end of the mold cavity away from the positioning block, and the second internal support rod is slidably disposed at the end of the mold cavity near the positioning block, and the second internal support rod extends into the insert through the positioning hole. The first internal support rod and the second internal support rod are respectively inserted into the inner cavity of the insert from both ends of the insert and are mated inside the insert. This application can improve the installation accuracy of the insert in the mold cavity before injection molding and improve the compressive strength of the insert tube wall during injection molding.

Description

Technical Field

[0001] This application relates to the technical field of molding materials in a plastic state, and in particular to an injection mold for a tubular insert. Background Technology

[0002] Insert injection molding, as a mature plastic processing technology, is widely used in many industrial fields such as electronics, automotive parts, and medical devices. The core of this process lies in precisely positioning a pre-made insert into a mold cavity, then closing the mold and injecting molten plastic. After cooling, the plastic body encapsulates and solidifies around the insert, forming a structurally and functionally integrated overmolded part. Overmolding is particularly common for tubular and rod-shaped inserts, such as when an insulating or cushioning layer needs to be coated onto the outer wall of a metal tube.

[0003] However, because the mold cavity itself needs to leave space for the injected molten plastic to fill, its size is inevitably larger than the outer dimensions of the insert. This results in a certain amount of movement allowance for the insert after it is placed in the cavity. During the placement of the insert, minute positioning errors can easily occur, affecting the uniformity of the overlay thickness and the product qualification rate.

[0004] In addition, during the injection of molten plastic, the melt exerts significant radial pressure on the insert's tube wall from all sides. For thin-walled or insufficiently rigid inserts, the pressure of the melt can cause indentation defects on the insert's tube wall, resulting in uneven wall thickness of the overlay layer and affecting the performance of the overlay part.

[0005] Therefore, in the current processing of overmolded parts, there are inherent deficiencies in both the installation and positioning of inserts within the mold cavity and the radial compressive deformation support, which restricts the stable production of high-quality, highly consistent overmolded parts. Summary of the Invention

[0006] In order to improve the installation accuracy of the insert in the mold cavity before injection molding and to improve the compressive strength of the insert tube wall during injection molding, this application provides a tubular insert injection mold.

[0007] The following technical solution is adopted: A tubular insert injection mold includes a mold body, wherein a cavity for receiving the insert is formed within the mold body, and further includes: The positioning block has a positioning hole, and one end of the insert is detachably connected to the positioning hole. One end of the mold cavity has a positioning groove for the positioning block to fit into. The internal support mechanism includes a first internal support rod and a second internal support rod arranged opposite to each other. The first internal support rod is slidably disposed at the end of the mold cavity away from the positioning block, and the second internal support rod is slidably disposed at the end of the mold cavity close to the positioning block. The second internal support rod extends into the insert through the positioning hole. The first inner support rod and the second inner support rod are inserted into the inner cavity of the insert from both ends of the insert and are joined together inside the insert.

[0008] By adopting the above technical solution, the positioning block is embedded in the positioning groove at the end of the mold cavity to form a precise fitting and positioning constraint. After one end of the insert is connected to the positioning block through the positioning hole, the axial position of the insert is limited by the fitting of the positioning block, which effectively eliminates the axial positioning error caused by the reserved filling space of the mold cavity during the placement of the insert, and ensures the uniformity of the thickness of the overlay layer. In the internal support mechanism, the first internal support rod and the second internal support rod are inserted into the inner cavity from both ends of the insert and docked, so that the insert obtains effective internal support throughout its entire length. During the injection molding process, they jointly resist the radial pressure of the injection liquid, effectively prevent the tube wall from being concave and deformed inward, and improve the dimensional accuracy and quality stability of the finished overlay part.

[0009] Optionally, the positioning hole includes a threaded hole section and an alignment hole section in sequence along the axial direction. The alignment hole section is coaxially arranged with the inner cavity of the insert. One end of the insert is set as an external thread end and is machined with external threads. The threaded hole section is threadedly connected to the external threaded end of the insert, and the alignment hole section is for the second inner support rod to pass through.

[0010] By adopting the above technical solution, the threaded hole section and the external threaded end of the insert form a detachable threaded connection, generating a stable axial preload, further eliminating the axial movement gap between the insert and the positioning block, ensuring reliable and repeatable positioning; the coaxial setting of the alignment hole section and the inner cavity of the insert is provided by the inlet guide provided by the second inner support rod, avoiding the second inner support rod from deviating and scratching the inner wall or causing uneven support force when it enters the insert; after injection molding, the insert can be easily separated from the positioning block by unscrewing it from the threaded hole section, making the operation simple.

[0011] Optionally, one end of the second inner support rod is provided with a snap-fit ​​protrusion, which is tapered, and one end of the first inner support rod is provided with a snap-fit ​​groove for the snap-fit ​​protrusion to be inserted.

[0012] By adopting the above technical solution, the tapering of the snap-fit ​​protrusion plays an automatic centering and guiding role when the first and second inner support rods complete blind docking inside the insert, guiding the snap-fit ​​protrusion to smoothly insert into the snap-fit ​​groove, reducing the requirements for docking accuracy. After the first and second inner support rods complete docking through the cooperation of the snap-fit ​​protrusion and the snap-fit ​​groove, they form a continuous and stable support body inside the insert, avoiding local support gaps caused by gaps at the docking point of the two rods. The tapering shape also allows the snap-fit ​​protrusion to smoothly disengage from the snap-fit ​​groove along the conical surface when the mold is opened and retracted, reducing the exit resistance.

[0013] Optionally, it also includes a locking structure and a pushing structure, the pushing structure being used to drive the first inner support rod to slide along the axial direction of the insert; The pushing structure includes a push block and a push rod. The push block is slidably disposed in the mold body, and one end of the first inner support rod is connected to the push block. The push rod is also slidably disposed within the mold body, with one end of the push rod extending outside the mold body and the other end connected to the push block; The locking structure is used to lock the position of the push block and the push rod after they have slid.

[0014] By adopting the above technical solution, the push rod extends to one end outside the mold body to facilitate external force application. The thrust is transmitted to the push block via the push rod, and then the push block directly drives the first inner support rod to insert into the inner cavity of the insert along the insert axis, realizing the controllable transmission of the insertion action of the first inner support rod. The locking structure locks the position of the push block and push rod after they are pushed into place, preventing the high pressure of the injection liquid from pushing back the first inner support rod and ensuring that the position of the inner support remains stable during the injection process.

[0015] Optionally, the locking structure includes a retaining plate and a locking block. The retaining plate is detachably connected to the outer wall of the mold body and is used to press against the end of the push rod located outside the mold body. The push block is provided with a guide slope, and the locking block is provided with a driving slope that matches the guide slope. When the driving slope pushes against the guide slope, the push block slides towards the mold cavity. In the mold closing state, the driving slope and the guide slope are completely in contact.

[0016] By adopting the above technical solution, the driving inclined surface of the locking pressure block and the guiding inclined surface of the push block cooperate with each other to convert the vertical closing motion during mold closing into the horizontal thrust of the push block. This drives the push block, together with the first inner support rod, to axially insert into the inner cavity of the insert, realizing the mechanical linkage between the mold closing action and the insertion action of the first inner support rod. There is no need to configure an additional independent driving device for the first inner support rod. When the mold is closed, the driving inclined surface and the guiding inclined surface are completely in contact. The self-locking effect generated by the contact of the inclined surfaces keeps the position of the push block stable. The clamping plate restricts the axial displacement of the push rod from the outside of the mold body, forming a double locking inside and outside, which effectively prevents the first inner support rod from retracting during injection molding.

[0017] Optionally, the pushing structure further includes a reset member, which is used to drive the first inner support rod to retract along its own axis when the mold is opened.

[0018] By adopting the above technical solution, the reset component automatically provides a reverse restoring force to the push block when the mold is opened, driving the push block together with the first inner support rod to actively exit the insert cavity, eliminating the need for manual removal by the operator, thus realizing the automatic reset of the first inner support rod and simplifying the operation steps; at the same time, the reset component keeps the push structure in the retracted position when not in operation, preventing the first inner support rod from accidentally extending and interfering with the part removal operation.

[0019] Optionally, it also includes a driving component, which includes a driving source and a driving slider. The driving slider is slidably disposed within the mold body. One end of the second inner support rod is connected to the driving slider. The driving source is used to drive the driving slider to slide along the axis of the second inner support rod.

[0020] By adopting the above technical solution, the drive component provides automatic driving force for the axial movement of the second inner support rod, reducing manual intervention and improving production efficiency.

[0021] Optionally, it also includes an alignment structure, which includes an alignment plate and an alignment insert. The alignment plate is disposed below the drive slider and has an alignment slot. In the mold closing state, the alignment insert is inserted into the alignment slot.

[0022] By adopting the above technical solution, the alignment structure limits the end point of the drive slider's stroke through the insertion and engagement of the alignment strip and the alignment slot, ensuring that the second inner support rod enters the insert cavity with a consistent insertion depth in each injection cycle to complete the docking, avoiding the two rods failing to dock or over-push interference due to stroke deviation, and improving the consistency and reliability of the injection molding operation.

[0023] Optionally, the second inner support rod includes, in sequence along the axial direction, a butt joint section, a contact support section, a non-contact support section, and a connecting section; The connecting rod section, contact support rod section, and non-contact support rod section are all used to pass through the insert. The outer diameter of the contact support rod section is adapted to the inner radial direction of the insert. The outer diameter of the non-contact support rod section is smaller than that of the contact support rod section. The axial length of the non-contact support rod section is greater than that of the contact support rod section. The outer diameter of the connecting rod segment is larger than the outer diameter of the non-contact support rod segment, and the end of the connecting rod segment near the non-contact support rod segment is inserted into the positioning hole. The non-contact support rod section is provided with an air intake channel arranged along the axial direction. Multiple rows of air injection hole groups are arranged circumferentially on the outer wall of the non-contact support rod section. Each air injection hole group includes multiple air injection holes distributed along the axial direction. The air injection holes are connected to the air intake channel, and the air intake channel is connected to the outside. An annular air cavity is formed between the outer wall of the non-contact support section and the inner wall of the insert. The mold body is also provided with an exhaust structure for discharging the gas in the annular air cavity outward.

[0024] By adopting the above technical solution, the second inner support rod is designed as a segmented structure. The connecting rod segment is responsible for engaging with the first inner support rod. The outer diameter of the contact support rod segment is adapted to the inner diameter of the insert, and the outer wall is in close contact with the inner wall of the insert. On the one hand, it provides direct physical support for part of the tube wall of the insert, and on the other hand, it isolates the two sides in the axial direction to prevent the injection molding liquid from entering the annular air cavity formed between the outer wall of the non-contact support rod segment and the inner wall of the insert. The air inlet channel delivers external gas to the multi-row air injection hole group and sprays it evenly into the air cavity to form a circumferentially distributed air column. This provides non-contact pressure equalization support for the inner wall of the longer tube section of the insert, effectively improving the problem of radial shrinkage of the insert and inner support rod during the injection cooling stage caused by the difference in thermal expansion coefficients of the materials, which leads to demolding difficulties and even scratches on the inner wall of the insert. The exhaust structure continuously discharges excess gas from the air cavity, maintains stable air cavity pressure, and prevents overpressure damage to the insert.

[0025] Optionally, the connecting rod section is provided with an air supply channel and an air venting channel. One end of the air supply channel is connected to the air inlet channel, and the other end is connected to an air supply pipe. The air supply pipe is located outside the mold body. One end of the venting channel is connected to the annular air cavity, and the other end is connected to a venting pipe, which is located outside the mold body. The exhaust structure includes the venting channel and the venting pipe, and the venting pipe is provided with a flow control element.

[0026] By adopting the above technical solution, both the air supply channel and the air venting channel are integrated inside the connecting rod section, forming an integrated air path layout for air intake and exhaust. The structure is compact and does not occupy additional space inside the mold body. Both the air supply pipe and the air venting pipe extend outside the mold body, which facilitates flexible connection to external air sources and exhaust without changing the mold body structure. The flow control component adjusts the exhaust rate at the outlet of the air venting pipe to maintain the air cavity pressure within a range that can effectively support the insert tube wall without overpressure. After injection molding and cooling, fully opening the flow control component can quickly release the air cavity pressure, significantly reducing the resistance to the second inner support rod's withdrawal and ensuring smooth demolding operation.

[0027] In summary, this application includes at least one of the following beneficial effects: 1. This application constrains the axial degree of freedom of the insert when it is placed into the mold cavity by precisely fitting the positioning block and the positioning groove, and by detachably connecting the insert and the positioning hole. This significantly reduces the axial positioning error of the insert and ensures the consistency of the outer coating thickness of the injection-molded parts and the product qualification rate. 2. This application uses a first inner support rod and a second inner support rod to be inserted from both ends of the insert and to complete the docking in the inner cavity of the insert, providing continuous internal support for the entire length of the insert, resisting the radial high pressure of the injection molding liquid, effectively preventing the insert tube wall from concave and deforming inward, and improving the tube wall roundness and the uniformity of the wall thickness of the adhesive layer of the finished coated part. 3. This application introduces a non-contact pneumatic support scheme between the inner wall of the insert and the second inner support rod through a non-contact support rod segment. This improves the cooling jamming and demolding difficulties caused by the difference in thermal expansion coefficients between the insert and the second inner support rod to a certain extent, and improves the smoothness of the second inner support rod when it retracts. Attached Figure Description

[0028] Figure 1 This is a cross-sectional view of the tubular insert injection mold in Embodiment 1 of this application; Figure 2 This is a schematic diagram of the structure of the male mold and the female mold when they are closed in Embodiment 1 of this application; Figure 3 This is a schematic diagram of the molding master mold structure illustrating the mold cavity structure in Embodiment 1 of this application; Figure 4 This is a cross-sectional view of the male mold and female mold in Embodiment 1 of this application; Figure 5 This is a schematic diagram of the molding master mold in Embodiment 2 of this application; Figure 6 This is a schematic diagram of the structure when the second inner support rod and the positioning block are engaged in Embodiment 2 of this application; Explanation of reference numerals in the attached figures: 1. Mold body; 11. Upper mold; 111. Injection port; 12. Lower mold; 121. Alignment strip; 13. Molding male mold; 14. Molding female mold; 15. Mold cavity; 151. Molding cavity; 152. Injection runner; 1521. Main runner; 1522. Branch runner; 16. Positioning groove; 161. Fitting groove section; 162. Receiving groove section; 17. Guide bracket; 171. Mounting back plate; 18. Mounting bracket; 19. Alignment plate; 191. Alignment slot; 2. Positioning block; 21. Positioning part; 22. Insert rod part; 23. Positioning hole; 231. Threaded hole section; 232. Alignment hole section; 24. Air inlet passage; 25. Air outlet passage; 3. First inner support rod; 31. Locking rod. 4. Receiving groove; 4. Second inner support rod; 41. Snap-fit ​​protrusion; 42. Connecting rod section; 43. Support rod section; 431. Contact support rod section; 432. Non-contact support rod section; 44. Connecting rod section; 45. Air inlet channel; 46. Air injection hole; 47. Air supply channel; 48. Air venting channel; 5. Pushing structure; 51. Push block; 511. Guide slope; 52. Push rod; 521. Limiting head; 53. Reset component; 6. Locking structure; 61. Pressing plate; 62. Locking pressure block; 621. Driving slope; 7. Driving assembly; 71. Driving source; 72. Driving slider; 8. Insert; 81. External thread end; 82. Annular air chamber; 9. Air venting pipe; 91. Flow control component; 10. Air supply pipe. Detailed Implementation

[0029] The following is in conjunction with the appendix Figure 1 -Appendix Figure 6 This application will be described in further detail.

[0030] Example 1

[0031] Embodiment 1 of this application provides a tubular insert injection mold.

[0032] refer to Figure 1 and Figure 2 The linear insert injection mold provided in this application includes a mold body 1, which includes an upper mold 11 and a lower mold 12. A molding male mold 13 is embedded in the bottom end of the upper mold 11 and is fixedly connected to the upper mold 11 by bolts. A molding female mold 14 is embedded in the top end of the lower mold 12 and is fixedly connected to the lower mold 12 by bolts. When the upper mold 11 and the lower mold 12 are closed, the molding male mold 13 and the molding female mold 14 are also closed, forming a mold cavity 15 between the molding male mold 13 and the molding female mold 14.

[0033] Reference Figure 1 and Figure 3 The mold cavity 15 includes a molding cavity 151 and an injection runner 152. The injection runner 152 includes a main runner 1521 and multiple branch runners 1522 connected to the main runner 1521. The multiple branch runners 1522 are distributed along the periphery of the molding cavity 151. An injection port 111 is provided on the upper end face of the upper mold 11, and the injection port 111 is connected to the main runner 1521. In this embodiment, two molding cavities 151 are machined, and the main runner 1521 is located between the two molding cavities 151. After the mold is closed, the injection molding liquid is injected from the injection port 111, so that the two molding cavities 151 can be injected simultaneously.

[0034] refer to Figure 3 and Figure 4 This application also includes a positioning block 2. A positioning groove 16 is provided at one end of the molding cavity 151, and the positioning groove 16 fits into the shape of the positioning block 2. The positioning block 2 includes an integrally formed positioning part 21 and an insert rod part 22. The positioning part 21 is wedge-shaped, and the insert rod part 22 is rod-shaped, with the cross-section of the insert rod part 22 being smaller than the cross-section of the positioning part 21. The positioning groove 16 includes a fitting groove section 161 and a receiving groove section 162. The cross-sectional shape of the fitting groove section 161 precisely matches the outer contour of the positioning part 21, and their fitting together constrains the positioning block 2 on a horizontal plane. The receiving groove section 162 allows the insert rod part 22 to pass through, and the cross-section of the insert rod part 22 is slightly smaller than the area enclosed by the inner wall of the receiving groove section 162, facilitating mold closing.

[0035] In other embodiments, the positioning block 2 may include only the positioning part 21, and the positioning groove 16 may include only the fitting groove section 161, so that the positioning part 21 and the positioning groove 16 are precisely fitted together.

[0036] refer to Figure 1and Figure 4 The positioning part 21 has a positioning hole 23, which includes a threaded hole section 231 and an alignment hole section 232 along the axial direction of the insert 8. One end of the insert 8 is provided as an external threaded end 81, and the outer wall of the external threaded end 81 is machined with external threads. The threaded hole section 231 is threadedly engaged with the external threaded end 81 of the insert 8. When the positioning block 2 is assembled into the positioning groove 16, the alignment hole section 232 remains coaxial with the inner cavity of the insert 8. Before injection molding, the operator screws the external threaded end 81 of the insert 8 into the threaded hole section 231 of the positioning block 2. After tightening, the insert 8 and the positioning block 2 form a detachable rigid threaded connection. Then, the positioning block 2 together with the insert 8 is placed into the lower mold 12. The positioning block 2 is embedded in the positioning groove 16 at the end of the mold cavity 15, thereby realizing the axial positioning of the insert 8 in the mold cavity 15.

[0037] In other embodiments, an annular groove can be machined at the end of the insert 8, and an elastic claw can be installed in the positioning hole 23 of the positioning block 2. After the insert 8 is inserted into the positioning hole 23, the elastic claw locks into the groove to achieve a snap-fit ​​detachable connection.

[0038] refer to Figure 3 and Figure 4 This application also includes an internal support mechanism, the number of which corresponds one-to-one with the molding cavity 151, specifically two of them. The internal support mechanism includes a first internal support rod 3 and a second internal support rod 4 arranged opposite to each other. One end of the first internal support rod 3 passes through the molding male mold 13 and the molding female mold 14 to the end of the molding cavity 151 away from the positioning block 2, and the first internal support rod 3 can slide into or out of the inner cavity of the insert 8 along the axial direction of the insert 8.

[0039] refer to Figure 3 and Figure 4 The second inner support rod 4 passes through the male mold 13 and the female mold 14 to the end of the molding cavity 151 near the positioning block 2. The second inner support rod 4 is slidably engaged with the male mold 13 and the female mold 14, and can pass through the alignment hole section 232 of the positioning block 2 and be inserted axially into the inner cavity of the insert 8. The end of the second inner support rod 4 near the first inner support rod 3 is provided with a snap-fit ​​protrusion 41, which is tapered towards the end. The end of the first inner support rod 3 near the second inner support rod 4 is provided with a snap-fit ​​groove 31, the inner contour of which matches the tapered shape of the snap-fit ​​protrusion 41.

[0040] After the insert 8 is assembled, the first inner support rod 3 and the second inner support rod 4 are inserted into the inner cavity from both ends of the insert 8. The snap-fit ​​protrusion 41 is inserted into the snap-fit ​​groove 31 at the end of the first inner support rod 3 under the guidance of the tapered conical surface, thus completing the snap-fit ​​connection of the first inner support rod 3 and the second inner support rod 4 in the inner cavity of the insert 8, so that the two rods form a continuous rigid inner support body along the entire length of the insert 8.

[0041] Specifically, the length of the first inner support rod 3 within the insert 8 is less than the length of the second inner support rod 4 within the insert 8. In this embodiment, the portion of the first inner support rod 3 inserted into the insert 8 occupies one-quarter of the total length of the insert 8. The outer diameter of the portion of the first inner support rod 3 inserted into the insert 8 is smaller than the inner diameter of the insert 8. The second inner support rod 4 includes, along the axial direction, an integrally formed mating rod segment 42, a support rod segment 43, and a connecting rod segment 44. A snap-fit ​​protrusion 41 is located at one end of the mating rod segment 42, and the outer diameter of the mating rod segment 42 is smaller than the inner diameter of the insert 8. The outer diameter of the support rod segment 43 is slightly larger than that of the mating rod segment 42, allowing the support rod segment 43 to fully fit against the insert 8. The connecting rod segment 44 is located outside the insert 8. One end of the connecting rod segment 44 is inserted into the alignment hole segment 232. The outer diameter of the connecting rod segment 44 is larger than that of the support rod segment 43. The outer diameter step surface stop formed between the connecting rod segment 44 and the inner wall of the alignment hole segment 232 constitutes an axial limit to prevent the second inner support rod 4 from being pushed excessively into the inner cavity of the insert 8.

[0042] Refer to Figure 2 and Figure 3 To drive the first inner support rod 3 to slide axially along the insert 8, a pushing structure 5 is also provided. The pushing structure 5 includes a push block 51, a push rod 52, and a reset member 53. The push block 51 and the push rod 52 are both located on one side of the forming mold 14 and are slidably fitted between the upper mold 11 and the lower mold 12. One end of the push rod 52 is fixedly connected to the push block 51. The upper end face of the lower mold 12 is also fixedly connected to a guide bracket 17 by bolts. The guide bracket 17 includes a mounting plate 171, which is located outside the mold body 1. One end of the push rod 52 passes through and is slidably fitted onto the mounting plate 171, and the end of the push rod 52 passing through the mounting plate 171 is fixedly connected to a limiting head 521. The limiting head 521 can abut against the mounting plate 171 to prevent the push rod 52 from slipping off. The reset member 53 is a reset spring, which is sleeved on the outside of the push rod 52 and fixedly connected between the limiting head 521 and the mounting plate 171. The end of the first inner support rod 3 furthest from the second inner support rod 4 is fixedly connected to the push block 51, and the two slide synchronously. One end of the push rod 52 extends outside the mold body 1, and the other end is connected to the push block 51; the pushing force is applied from the end of the push rod 52 located outside the mold body 1, transmitted to the push block 51 via the push rod 52, and then the push block 51 drives the first inner support rod 3 to axially insert into the inner cavity of the insert 8. The reset member 53 accumulates elastic restoring force after being compressed, and drives the push block 51 together with the first inner support rod 3 to return to the initial position axially when the mold opening locking force is released, thereby achieving automatic reset.

[0043] In other embodiments, the reset member 53 may also be an elastic rubber sleeve.

[0044] refer to Figure 1 and Figure 3The mold body 1 has a locking structure 6 at one end where the pushing structure 5 is located. The locking structure 6 includes a pressing plate 61 and a locking block 62. The locking block 62 is fixed to the upper mold 11 by bolts. A driving inclined surface 621 is machined on the locking block 62. A guide inclined surface 511 is correspondingly provided on the push block 51. The inclination direction of the driving inclined surface 621 and the guide inclined surface 511 are adapted to each other. During the mold closing process, the upper mold 11 moves towards the lower mold 12. The locking block 62 moves down synchronously with the upper mold 11. The driving inclined surface 621 and the guide inclined surface 511 gradually come into contact and squeeze, generating a horizontal component force to push the push block 51 and the first inner support rod 3 axially towards the inner cavity of the insert 8, realizing the mechanical linkage between the mold closing action and the insertion action of the first inner support rod 3. When the mold is closed in place, the driving inclined surface 621 and the guide inclined surface 511 are completely in contact, and the push block 51 is locked at the push termination position. The self-locking effect of the inclined surface prevents the push block 51 from sliding back due to the injection liquid pressure. The clamping plate 61 is detachably connected to the outer wall of the mold body 1 by bolts. Its end face abuts against the end of the push rod 52 that extends outside the mold body 1, preventing the push rod 52 from moving outward along the axial direction. Together with the inclined self-locking, it forms a double locking of the pushing structure 5. The mold closing structure design and mold closing operation are common technical means in the industry and are known to those skilled in the art. This application will not describe them in detail.

[0045] refer to Figure 1 , Figure 2 and Figure 3 To drive the second inner support rod 4 to slide axially along the insert 8 and to ensure that the second inner support rod 4 is inserted into place, the mold body 1 is also provided with a drive assembly 7 and an alignment structure. The drive assembly 7 includes a drive source 71 and a drive slider 72. Both the drive slider 71 and the drive source 72 are located on the side of the forming mold 14 away from the push structure 5. The drive slider 72 is slidably fitted between the upper mold 11 and the lower mold 12. The drive source 71 is located outside the mold body 1. The upper end face of the lower mold 12 is fixed to a mounting bracket 18 by bolts, and the drive source 71 is fixed to the mounting bracket 18. The end of the second inner support rod 4 away from the first inner support rod 3 is fixedly connected to the drive slider 72. The drive source 71 can be a hydraulic cylinder. The piston rod of the hydraulic cylinder is directly connected to the drive slider 72. By introducing or discharging hydraulic oil into the hydraulic cylinder, the piston rod is driven to extend or retract, thereby driving the drive slider 72 and the second inner support rod 4 to move forward and backward.

[0046] The alignment structure includes an alignment plate 19 and alignment inserts 121. The alignment plate 19 is located below the drive slider 72 and is fixed to the lower mold 12 by bolts. Alignment slots 191 are provided on the alignment plate 19. One end of the alignment insert 121 is fixed to the upper mold 11 by bolts, and two alignment inserts 121 are spaced apart. Two alignment slots 191 are also provided on the alignment plate 19 corresponding to the alignment inserts 121. In the mold-closed state, the alignment inserts 121 are inserted into the lower mold 12 through the alignment slots 191, limiting the sliding termination position of the drive slider 72 and ensuring that the second inner support rod 4 penetrates the inner cavity of the insert 8 with a consistent insertion depth each time, thus ensuring reliable docking of the first inner support rod 3 and the second inner support rod 4.

[0047] The implementation principle of a tubular insert injection mold according to an embodiment of this application is as follows: Before injection molding, the operator screws the external threaded end 81 of the insert 8 into the threaded hole section 231 of the positioning block 2, completing the threaded connection between the insert 8 and the positioning block 2. Then, the positioning block 2, together with the insert 8, is placed into the molding cavity 151. The positioning block 2 is embedded in the positioning groove 16, realizing the axial positioning of the insert 8 in the mold cavity 15. The drive source 71 is started, first driving the drive slider 72 to push the second inner support rod 4 through the alignment hole section 232 into the inner cavity of the insert 8. The drive slider 72 stops when it reaches the limited position. Then, the push rod 52 is pushed, driving the push block 51 to push the first inner support rod 3 into the inner cavity of the insert 8 until the push block 51 slides to the end of its stroke. Then, the mold is closed.

[0048] During mold closing, the upper mold 11 moves the locking block 62 and the alignment strip 121 downwards. The driving slope 621 of the locking block 62 gradually contacts the guide slope 511 of the push block 51, generating a horizontal thrust. The push block 51 further drives the first inner support rod 3 to axially insert into the inner cavity of the insert 8. After the mold is closed, the driving slope 621 and the guide slope 511 are fully engaged, and the alignment strip 121 is inserted into the alignment slot 191. Then, the mounting clamping plate 61 is used to press against the protruding end of the push rod 52, completing the locking of the insertion state of the first inner support rod 3 and the second inner support rod 4.

[0049] The snap-fit ​​protrusion 41 at the end of the second inner support rod 4 is guided by the tapered conical surface and inserted into the snap-fit ​​groove 31 at the end of the first inner support rod 3. The two rods are snapped together in the inner cavity of the insert 8, providing continuous internal support for the entire length of the insert 8.

[0050] Subsequently, molten injection molding liquid is injected into the mold cavity 15. The first inner support rod 3 and the second inner support rod 4 work together to resist the radial pressure of the injection molding liquid on the tube wall of the insert 8, preventing the tube wall of the insert 8 from being concave and deformed inward.

[0051] After cooling, the drive source 71 reverses the direction to drive the second inner support rod 4 out of the inner cavity of the insert 8; when the mold opens, the clamping plate 61 is removed, the upper mold 11 rises, the locking block 62 disengages from the guide slope 511, and the reset member 53 pushes the push block 51 together with the first inner support rod 3 back to the initial position, and the first inner support rod 3 exits the inner cavity of the insert 8; the insert 8 together with the outer rubber layer is taken out from the mold cavity 15, and the insert 8 is screwed out from the threaded hole section 231 of the positioning block 2 to complete one injection molding process.

[0052] Example 2

[0053] Embodiment 2 of this application provides a tubular insert injection mold.

[0054] The difference between Embodiment 2 and Embodiment 1 of this application is as follows: refer to Figure 5 and Figure 6 The support rod segment 43 in the second inner support rod 4 includes a contact support rod segment 431 and a non-contact support rod segment 432 connected in sequence. After the first inner support rod 3 and the second inner support rod 4 are connected in the insert 8, the connecting rod segment 42, the contact support rod segment 431 and the non-contact support rod segment 432 are all inserted into the inner cavity of the insert 8.

[0055] The outer diameter of the contact support section 431 is adapted to the inner radial direction of the insert 8, and the outer wall of the contact support section 431 is in close contact with the inner wall of the insert 8. This provides direct physical support to the pipe wall of the insert 8 near the positioning block 2, and also isolates the areas on both sides of the contact support section 431 axially, preventing the injection molding liquid from intruding into the area where the non-contact support section 432 is located along the inner wall of the insert 8. The outer diameter of the non-contact support section 432 is smaller than that of the contact support section 431, and an annular air cavity 82 for distributing the air column is formed between the outer wall of the non-contact support section 432 and the inner wall of the insert 8. The axial length of the non-contact support section 432 is greater than that of the contact support section 431, covering the internal support requirements within the main length range of the insert 8.

[0056] refer to Figure 5 and Figure 6 An air intake channel 45 extends axially within the non-contact support section 432. Multiple rows of air injection holes are spaced circumferentially on the outer wall of the non-contact support section 432. Each air injection hole group includes multiple air injection holes 46 evenly distributed axially, and each air injection hole 46 is connected to the air intake channel 45. The air intake channel 45 is supplied with air from an external air source. The gas is evenly ejected into the annular air cavity 82 through the air injection hole group, forming a circumferentially evenly distributed supporting air column within the annular air cavity 82, applying a uniform radial air pressure support force to the inner wall of the insert 8. In this embodiment, the air injection hole group has four rows evenly distributed circumferentially.

[0057] refer to Figure 5 and Figure 6The connecting rod section 44 is machined with an air supply channel 47 and an air venting channel 48. In this embodiment, the insert rod portion 22 in the positioning block 2 is strip-shaped and extended, with one end of the insert rod portion 22 extending out of the mold body 1 (not shown in the figure) facing upwards towards the mold 11. The positioning block 2 is machined with an air inlet passage 24 and an air outlet passage 25. The insert rod portion 22 is connected to an air supply pipe 10 and an air venting pipe 9 via quick connectors. One end of the air inlet passage 24 is connected to the air supply pipe 10, and one end of the air outlet passage 25 is connected to the air venting pipe 9. One end of the air supply channel 47 is connected to the air inlet channel 45, and the other end is connected to the air inlet passage 24, so as to indirectly realize the connection between the air supply channel 47 and the air inlet channel 45. One end of the air supply pipe 10 is connected to an external air source; the external air source delivers gas to the air inlet channel 45 through the air supply pipe 10 and the air supply channel 47 to maintain the air column pressure in the annular air chamber 82.

[0058] One end of the venting channel 48 is connected to the annular air chamber 82, and the other end is connected to the outlet air passage 25, thereby indirectly connecting the venting channel 48 to the venting pipe 9. The venting channel 48, the outlet air passage 25, and the venting pipe 9 are connected in sequence to form an exhaust structure. A flow control element 91 is installed on the venting pipe 9. By adjusting the opening of the flow control element 91, the exhaust rate of the annular air chamber 82 is controlled, so that the air column pressure of the annular air chamber 82 is stably maintained within a preset safe range, preventing overpressure damage to the insert 8. The flow control element 91 can be in the form of a needle valve, a stop valve, or a proportional regulating valve, etc. By adjusting the opening of the valve core, the airflow passage area at the outlet of the venting pipe 9 is changed, thereby controlling the exhaust rate of the annular air chamber 82.

[0059] During injection molding, the exhaust rate is adjusted to balance the intake rate by controlling the opening of the flow control element 91, ensuring that the pressure in the annular air chamber 82 is stably maintained near the target air column pressure. This guarantees uniform support for the insert 8 tube wall and prevents the pressure in the annular air chamber 82 from continuously accumulating and exceeding the safety threshold. After injection molding and cooling, the flow control element 91 is fully opened to quickly remove the residual air pressure in the annular air chamber 82, significantly reducing the resistance to the retraction of the second inner support rod 4.

[0060] After injection molding and cooling, the external air source is shut off, and the flow control component 91 is fully opened. The residual gas in the annular air chamber 82 is quickly discharged to the outside through the vent pipe 9, and the air chamber pressure quickly drops to a level close to the outside atmospheric pressure. After the air chamber is completely depressurized, the second inner support rod 4 is driven to exit the inner cavity of the insert 8. Since the annular air chamber 82 has been depressurized and the outer wall of the non-contact support rod section 432 has no contact with the inner wall of the insert 8 throughout the process, the non-contact support rod section 432 of the second inner support rod 4 experiences very little resistance during exit. Although the contact support rod section 431 is in contact with the inner wall of the insert 8, its axial length is relatively short, and the contact friction resistance is limited. Therefore, the entire exit process of the second inner support rod 4 is smooth, which significantly improves the problems of cooling seizing and demolding difficulties caused by the difference in thermal expansion coefficients between the insert 8 and the second inner support rod 4. The portion of the first inner support rod 3 located inside the insert and the connecting rod section 42 of the second inner support rod 4 are covered by the plastic body obtained after the injection molding liquid is cooled after injection molding. Since the plastic body has a certain elasticity, the connecting rod section 42 of the first inner support rod 3 and the second inner support rod 4 can be removed smoothly and is less likely to damage the insert 8.

[0061] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A tubular insert injection mold comprising a mold body (1) in which a mold cavity (15) for accommodating an insert (8) is formed, characterized in that, Also includes: The positioning block (2) has a positioning hole (23) and one end of the insert (8) is detachably connected to the positioning hole (23). One end of the mold cavity (15) is provided with a positioning groove (16) for the positioning block (2) to fit into. The internal support mechanism includes a first internal support rod (3) and a second internal support rod (4) arranged opposite to each other. The first internal support rod (3) is slidably disposed at one end of the mold cavity (15) away from the positioning block (2), and the second internal support rod (4) is slidably disposed at one end of the mold cavity (15) close to the positioning block (2). The second internal support rod (4) passes through the positioning hole (23) and extends into the insert (8). The first internal support rod (3) and the second internal support rod (4) are respectively inserted into the inner cavity of the insert (8) from both ends of the insert (8) and are connected in the insert (8).

2. A tubular insert injection mold according to claim 1, wherein The positioning hole (23) includes a threaded hole section (231) and a positioning hole section (232) in sequence along the axial direction. The positioning hole section (232) is coaxially arranged with the inner cavity of the insert (8). One end of the insert (8) is set as an external thread end (81) and is machined with external threads. The threaded hole section (231) is threadedly connected to the external threaded end (81) of the insert (8), and the alignment hole section (232) is for the second inner support rod (4) to pass through.

3. A tubular insert injection mold according to claim 2, wherein The second inner support rod (4) has a snap-fit ​​protrusion (41) at one end, the snap-fit ​​protrusion (41) is tapered, and the first inner support rod (3) has a snap-fit ​​groove (31) at one end for the snap-fit ​​protrusion (41) to be inserted.

4. The tubular insert injection mold according to claim 1, characterized in that, It also includes a locking structure (6) and a pushing structure (5), the pushing structure (5) being used to drive the first inner strut (3) to slide along the axial direction of the insert (8); The pushing structure (5) includes a push block (51) and a push rod (52). The push block (51) is slidably disposed inside the mold body (1). One end of the first inner support rod (3) is connected to the push block (51). The push rod (52) is also slidably disposed inside the mold body (1), and one end of the push rod (52) extends outside the mold body (1), while the other end is connected to the push block (51); The locking structure (6) is used to lock the position of the push block (51) and the push rod (52) after they have slid.

5. The tubular insert injection mold according to claim 4, characterized in that, The locking structure (6) includes a clamping plate (61) and a locking block (62). The clamping plate (61) is detachably connected to the outer wall of the mold body (1) and is used to clamp the end of the push rod (52) located outside the mold body (1). The push block (51) is provided with a guide slope (511), and the locking block (62) is provided with a driving slope (621) that is adapted to the guide slope (511). When the driving slope (621) pushes against the guide slope (511), the push block (51) slides towards the mold cavity (15). In the mold closing state, the driving slope (621) and the guide slope (511) are completely in contact.

6. The tubular insert injection mold according to claim 4, characterized in that, The pushing structure (5) also includes a reset member (53), which is used to drive the first inner support rod (3) to retract along its own axis when the mold is opened.

7. A tubular insert injection mold according to any one of claims 1-6, characterized in that, It also includes a drive assembly (7), which includes a drive source (71) and a drive slider (72). The drive slider (72) is slidably disposed inside the mold body (1). One end of the second inner support rod (4) is connected to the drive slider (72). The drive source (71) is used to drive the drive slider (72) to slide along the axis of the second inner support rod (4).

8. A tubular insert injection mold according to claim 7, characterized in that, It also includes a alignment structure, which includes an alignment plate (19) and an alignment insert (121). The alignment plate (19) is located below the drive slider (72), and an alignment slot (191) is provided on the alignment plate (19). In the mold closing state, the alignment insert (121) is inserted into the alignment slot (191).

9. A tubular insert injection mold according to any one of claims 1-6, characterized in that, The second inner support rod (4) includes, in sequence along the axial direction, a butt joint rod section (42), a contact support rod section (431), a non-contact support rod section (432), and a connecting rod section (44). The connecting rod section (42), the contact support rod section (431), and the non-contact support rod section (432) are all used to be inserted into the insert (8). The outer diameter of the contact support rod section (431) is adapted to the inner radial direction of the insert (8). The outer diameter of the non-contact support rod section (432) is smaller than the outer diameter of the contact support rod section (431). The axial length of the non-contact support rod section (432) is greater than the axial length of the contact support rod section (431). The outer diameter of the connecting rod segment (44) is larger than the outer diameter of the non-contact support segment (432), and the end of the connecting rod segment (44) near the non-contact support segment (432) is inserted into the positioning hole (23); The non-contact support rod section (432) is provided with an air intake channel (45) arranged along the axial direction. Multiple rows of air injection hole groups are arranged circumferentially on the outer wall of the non-contact support rod section (432). Each air injection hole group includes multiple air injection holes (46) distributed along the axial direction. The air injection holes (46) are connected to the air intake channel (45). The air intake channel (45) is connected to the outside. An annular air cavity (82) is formed between the outer wall of the non-contact support segment (432) and the inner wall of the insert (8). The mold body (1) is also provided with an exhaust structure for discharging the gas in the annular air cavity (82) outward.

10. A tubular insert injection mold according to claim 9, characterized in that, The connecting rod section (44) is provided with an air supply channel (47) and an air venting channel (48). One end of the air supply channel (47) is connected to the air inlet channel (45), and the other end is connected to an air supply pipe (10). The air supply pipe (10) is located outside the mold body (1). One end of the venting channel (48) is connected to the annular air cavity (82), and the other end is connected to the venting pipe (9). The venting pipe (9) is located outside the mold body (1). The exhaust structure includes the venting channel (48) and the venting pipe (9), and the venting pipe (9) is provided with a flow control element (91).

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