Injection mold stub bar self-cutting-off time-delay rotary ejection mechanism

Abstract

The utility model discloses an injection mold stub bar self-cutting delay rotary ejection mechanism, which comprises an ejector plate, a back-off type delay ejector mechanism and a rotary type delay ejector mechanism, the back-off type delay ejector mechanism comprises a back-off needle and a first delay ejection device arranged at one end of the back-off needle, the other end of the back-off needle is provided with a back-off forming part, and the rotary type delay ejector mechanism is arranged at the other end of the back-off needle. A stub bar formed at the sprue position of the injection mold can form a part with an inverted buckle in the mold opening and closing direction through the inverted buckle forming part; the rotary delay ejector pin mechanism comprises a rotary pin, a second delay ejection device arranged at one end of the rotary pin and a rotary limiting device; the ejector pin plate is used for driving the back-off pin and the rotating pin to eject the stub bar in a delayed mode through the first delayed ejection device and the second delayed ejection device and forcing the rotating pin to drive the stub bar to rotate through the rotating limiting device. The material head and the product can be automatically cut off, the product is effectively prevented from being scratched by adjusting the direction of the material head, and a manipulator can conveniently take out the product.

Description

Technical Field

[0001] This utility model relates to the field of injection mold technology, and in particular to an injection mold material head self-cutting delayed rotation ejection mechanism. Background Technology

[0002] In the injection molding industry, the traditional method of removing sprue after molding mainly relies on manual operation or the use of shears, which inevitably requires a dedicated post-molding sprue processing step. This process is not only labor-intensive but also extremely inefficient. For example, in the mass production of plastic products, each product requires manual or tool-assisted sprue cutting, which severely limits production speed and makes it difficult to meet the needs of large-scale production, resulting in high production costs.

[0003] Although there are existing technologies for in-mold automatic sprue cutting, for products with extremely high appearance quality requirements, if the sprue ejects and falls off after cutting, it is highly likely to scratch the product's appearance, causing defects and seriously affecting product quality. Since the sprue's position is determined based on mold flow analysis, the sprue's position and angle cannot be arbitrarily changed and must be placed according to the angle and position specified by the mold flow analysis. Therefore, if the sprue is positioned above the product, the ejected sprue will collide with the product, causing appearance defects. Furthermore, when the sprue is in a narrow location, it is difficult for a robotic arm to simultaneously handle the removal of both the product and the sprue. Therefore, it is necessary to improve existing technologies to overcome their shortcomings. Utility Model Content

[0004] The problem to be solved by this utility model is to provide a self-cutting delayed rotation ejection mechanism for injection mold sprues, so as to overcome the defects of existing injection molds in the process of separating and removing products from sprues, such as low production efficiency, easy damage to products, and difficulty in operation in narrow spaces.

[0005] The technical solution adopted by this utility model to solve its technical problem is: a self-cutting delayed rotary ejection mechanism for injection mold sprues, comprising: an ejector plate and an undercut delayed ejector mechanism and a rotary delayed ejector mechanism, both mounted on the ejector plate along the opening and closing direction of the injection mold. The undercut delayed ejector mechanism includes an undercut pin and a first delayed ejection device disposed at one end of the undercut pin. The other end of the undercut pin is provided with an undercut forming part. The sprue formed at the gate position of the injection mold can form an undercut portion in the opening and closing direction through the undercut forming part. The rotary delayed ejector mechanism includes a rotating pin, a second delayed ejection device disposed at one end of the rotating pin, and a rotation limiting device. The ejector plate is used to drive the undercut pin and the rotating pin to eject the sprue in a delayed manner through the first delayed ejection device and the second delayed ejection device, and can force the rotating pin to drive the sprue to rotate through the rotation limiting device.

[0006] As a further improvement of this utility model, the first delayed ejection device includes a first sheath, a first spring, and a first ejector rod. The first sheath is fixed to the ejector plate. One end of the undercut pin passes through the first sheath and abuts against one end of the first ejector rod. The other end of the first ejector rod passes through the ejector plate and abuts against the bottom plate of the injection mold. The first spring is fitted on the undercut pin, and both ends of the first spring elastically abut against the step at one end of the undercut pin and the top of the first sheath, respectively.

[0007] As a further improvement of this utility model, the undercut forming part is machined from one end of the undercut pin, and the undercut forming part has two L-shaped cutting surfaces, and the included angle between the two cutting surfaces is an acute angle.

[0008] As a further improvement of this utility model, the second delayed ejection device includes a second sheath, a second spring, and a second push rod. The second sheath is fixed to the ejector plate, and one end of the rotating needle passes through the second sheath and abuts against one end of the second push rod. The second spring is fitted on the rotating needle, and the two ends of the second spring elastically abut against the step at one end of the rotating needle and the top of the second sheath, respectively.

[0009] As a further improvement of this utility model, a pressure block for pressing the second sheath is detachably fixed to the bottom of the ejector plate, and a stop block opposite to the pressure block is detachably fixed to the bottom plate of the injection mold, and the other end of the second ejector rod passes through the pressure block and abuts against the stop block.

[0010] As a further improvement of this utility model, the rotating limiting device includes a limiting bolt and a steel ball. The limiting bolt is fixed on the rear mold of the injection mold, and the steel ball is disposed at one end of the limiting bolt. A track groove is provided on the side of the rotating needle, and the steel ball rolls in contact with the track groove.

[0011] As a further improvement of this utility model, the track groove includes an upper groove body, a lower groove body, and an arc-shaped groove body connecting the upper groove body and the lower groove body. The upper groove body and the lower groove body are both arranged parallel to the axis of the rotating needle, and the upper groove body and the lower groove body are staggered in the circumferential direction of the rotating needle.

[0012] As a further improvement of this utility model, a guide sleeve is also fixed on the rear mold of the injection mold, and the guide sleeve is slidably fitted on the rotating needle.

[0013] As a further improvement of this utility model, the injection mold sprue head self-cutting delayed rotation ejection mechanism also includes a synchronous delayed ejector pin mechanism. The synchronous delayed ejector pin mechanism includes a synchronous pin and a third ejector rod. The ejector pin plate is provided with a limiting cavity. One end of the synchronous pin passes through the limiting cavity and abuts against one end of the third ejector rod. The other end of the third ejector rod passes through the ejector pin plate and abuts against the bottom plate of the injection mold.

[0014] As a further improvement of this utility model, the reverse pin is disposed at the end where the material head connects to the product.

[0015] The beneficial effects of this utility model are as follows: This utility model provides a self-cutting delayed rotary ejection mechanism for injection mold sprues. By setting an inverted delayed ejector pin mechanism and a rotary delayed ejector pin mechanism on the rear mold, the inverted pins that are ejected during the delay hold the sprue head, realizing automatic cutting of the sprue head from the product. This eliminates the need for manual cutting or cutting with shears, reducing labor input, improving production efficiency, enabling mass production and reducing production costs. At the same time, the rotating pin allows the sprue head to adjust its direction during the delayed ejection process, keeping it away from the product. This not only effectively avoids the problem of the sprue head falling off and scratching the product's appearance, but also facilitates the smooth removal operation by the robotic arm. It is no longer limited by the position and angle of the injection port, enhancing the adaptability of the mold under different injection port settings and improving production flexibility. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a perspective view of the injection mold head self-cutting delayed rotation ejection mechanism of this utility model installed in the rear mold part;

[0018] Figure 2 This is a front view of the injection mold sprue self-cutting delayed rotation ejection mechanism of this utility model installed in the rear mold part;

[0019] Figure 3 This utility model is based on Figure 2 Cross-sectional view along the AA direction;

[0020] Figure 4 This utility model Figure 3 Enlarged view of section C;

[0021] Figure 5 This utility model is based on Figure 2 Cross-sectional view along the BB direction;

[0022] Figure 6 This utility model Figure 5 Enlarged view of section D in the middle;

[0023] Figure 7 This is a perspective view of the injection mold sprue self-cutting delayed rotating ejection mechanism of this utility model;

[0024] Figure 8 This is a perspective view of the inverted delay pin mechanism of this utility model;

[0025] Figure 9 This is a perspective view of the rotary delay ejector mechanism of this utility model;

[0026] Figure 10 This is a cross-sectional view showing the synchronous delay ejector mechanism of this utility model.

[0027] Referring to the accompanying drawings, the following explanations are provided:

[0028] 1. Ejector plate; 101. Limiting cavity; 2. Backing pin; 201. Backing forming part;

[0029] 2011, Cutting surface; 3, Rotating pin; 301, Track groove; 3011, Upper groove body; 3012, Lower groove body; 3013, Arc-shaped groove body; 4, First protective sleeve; 401, Limiting groove; 5, First spring; 6, First ejector rod; 7, Base plate; 8, Second protective sleeve; 9, Second spring; 10, Second ejector rod; 11, Pressure block; 12, Stop block; 13, Limiting bolt; 14, Steel ball; 15, Rear mold; 16, Guide sleeve; 17, Synchronizing pin; 18, Third ejector rod; 19, Rear mold core; 20, Limiting pin; 100, Material head. Detailed Implementation

[0030] The present application will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0031] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. This application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0032] It should be noted that various aspects of embodiments within the scope of the appended claims are described below. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this application, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number and aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using structures and / or functionalities other than one or more of the aspects set forth herein.

[0033] It should also be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of this application. The illustrations only show the components related to this application and are not drawn according to the number, shape and size of the components in actual implementation. In actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0034] Additionally, specific details are provided in the following description to facilitate a thorough understanding of the examples. However, those skilled in the art will understand that practice can be carried out without these specific details.

[0035] The technical solutions provided by the various embodiments of this application are described below with reference to the accompanying drawings.

[0036] See Figure 1 and Figure 2This utility model provides a self-cutting delayed rotary ejection mechanism for injection mold sprues, comprising: an ejector plate 1, an inverted delayed ejector mechanism, and a rotary delayed ejector mechanism. The ejector plate 1 is movably disposed between the rear mold 15 and the base plate 7 of the injection mold, and can be driven by an external power device such as a hydraulic cylinder to perform ejection movement. In this embodiment, the ejector plate 1 is formed by a fixedly stacked upper ejector plate and a lower ejector plate. Both the inverted delayed ejector mechanism and the rotary delayed ejector mechanism are mounted on the ejector plate 1 along the mold opening and closing direction of the injection mold.

[0037] like Figure 3 and Figure 4 As shown, the undercut delayed ejector mechanism includes an undercut pin 2 and a first delayed ejection device disposed at the lower end of the undercut pin 2. The upper end of the undercut pin 2 extends vertically upward through the rear mold 15 and the rear mold core 19 to the gate of the injection mold. The upper end of the undercut pin 2 is provided with an undercut forming part 201. The sprue 100 formed at the gate position of the injection mold can be formed with an undercut part in the mold opening and closing direction through the undercut forming part 201.

[0038] like Figure 5 and Figure 6 As shown, the rotary delayed ejector mechanism includes a rotating pin 3, a second delayed ejection device located at the lower end of the rotating pin 3, and a rotation limiting device. The upper end of the rotating pin 3 also extends vertically upward through the rear mold 15 and the rear mold core 19 to the gate of the injection mold. The ejector plate 1 is used to drive the undercut pin 2 and the rotating pin 3 to eject the sprue 100 with a delayed ejection through the first delayed ejection device and the second delayed ejection device, and can force the rotating pin 3 to drive the sprue 100 to rotate through the rotation limiting device.

[0039] After the product cools and solidifies, the front mold and rear mold 15 of the injection mold open relative to each other. Then, the ejector plate 1 is driven by an external power device to push the ejector pins upward. Under the action of the first delayed ejection device and the second delayed ejection device, the undercut pin 2 and the rotating pin 3 remain stationary during the initial upward ejection of the ejector plate 1. At this time, the undercut forming part 201 on the undercut pin 2 can hold the sprue 100, so that the product is automatically cut off from the sprue 100 under the push of the ejector pin. After the ejector plate 1 moves upward by the set delay distance, it starts to push the undercut pin 2 and the rotating pin 3 upward synchronously through the first delayed ejection device and the second delayed ejection device. During the upward ejection of the sprue 100, the rotating pin 3 can be forced to rotate the sprue 100 by a certain angle through the rotation limit device until the sprue 100 is fully ejected. Then, the product and the sprue 100 are taken out simultaneously by the robot.

[0040] This invention, by setting an inverted delayed ejector pin mechanism and a rotary delayed ejector pin mechanism on the rear mold 15, utilizes the delayed ejected inverted pin 2 to hold the material head 100, achieving automatic cutting of the material head 100 from the product. This eliminates the need for manual cutting of the material head 100 using shears, reducing labor input, improving production efficiency, enabling mass production, and lowering production costs. Simultaneously, the rotary pin 3 allows the material head 100 to adjust its direction during the delayed ejection process, moving it away from the product. This effectively prevents the material head 100 from falling and scratching the product's surface, and facilitates smooth removal by the robotic arm. It is no longer limited by the position and angle of the injection port, enhancing the mold's adaptability to different injection port settings and improving production flexibility.

[0041] See Figure 3 and Figure 4 The first delayed ejection device includes a first sleeve 4, a first spring 5, and a first ejector rod 6. The first sleeve 4 is a cylindrical shape with a top but no bottom and a stepped outer surface. It is fixed to the ejector plate 1. The lower end of the underpin 2 passes through the first sleeve 4 and abuts against the upper end of the first ejector rod 6. The first spring 5 is fitted onto the underpin 2, and its two ends elastically abut against the step at the lower end of the underpin 2 and the top of the first sleeve 4, respectively. The lower end of the first ejector rod 6 passes through the ejector plate 1 and abuts against the bottom plate 7 of the injection mold.

[0042] like Figure 7 and Figure 8 As shown, in this embodiment, the first push rod 6 is inverted U-shaped; correspondingly, the bottom of the first sheath 4 is provided with a clearance groove for the first push rod 6 to move.

[0043] When the ejector plate 1 is pushed upward, the buckle pin 2 and the first push rod 6 remain stationary under the elastic force of the first spring 5. Until the portion of the ejector plate 1 crossed by the first push rod 6 presses against the inner top surface of the first push rod 6, the ejector plate 1 then begins to push the buckle pin 2 and the first push rod 6 upward synchronously during the subsequent pushing process. When the ejector plate 1 returns to its original position, the base plate 7 stops the first push rod 6, thereby pushing the buckle pin 2 back to its original position.

[0044] See Figure 4 A limiting pin 20 is fixed radially on the step at the lower end of the buckle pin 2. A limiting groove 401 is provided on the inner wall of the first sheath 4 along the ejection direction. The limiting pin 20 extends into the limiting groove 401 to circumferentially limit the buckle pin 2 and prevent it from rotating.

[0045] It is worth mentioning that the inverted pin 2 of this utility model is set at the end where the material head 100 is connected to the product, so that the product and the material head are not easily pulled and deformed during the cutting process, ensuring that the product appearance is not damaged, thereby improving product quality and reducing the product scrap rate caused by poor appearance.

[0046] See Figure 8 The undercut forming part 201 is machined from one end of the undercut pin 2. The undercut forming part 201 has two L-shaped cutting surfaces 2011, one of which is horizontally distributed, and the other is inclined at a certain angle relative to the vertical surface, and the included angle between the two cutting surfaces 2011 is an acute angle. By adopting this structural design, this utility model can form an undercut part on the material head 100; on the other hand, when the rotating pin 3 drives the material head 100 to rotate, the material head 100 can be smoothly disengaged from the undercut forming part 201.

[0047] See Figure 5 and Figure 6 The second delayed ejection device includes a second sheath 8, a second spring 9, and a second ejector rod 10. The second sheath 8 is also a cylindrical shape with a top but no bottom and a stepped outer surface, and it is fixed to the ejector plate 1. The lower end of the rotating needle 3 passes through the second sheath 8 and abuts against the upper end of the second ejector rod 10. The second spring 9 is fitted onto the rotating needle 3, and the two ends of the second spring 9 elastically abut against the step at the lower end of the rotating needle 3 and the top of the second sheath 8, respectively.

[0048] In this embodiment, the second top rod 10 is a cylinder with a hanging platform at the top.

[0049] Furthermore, a pressure block 11 for pressing the second sheath 8 is detachably fixed to the bottom of the ejector plate 1; a stop block 12 opposite to the pressure block 11 is detachably fixed to the bottom plate 7 of the injection mold, and the lower end of the second ejector rod 10 passes through the pressure block 11 and abuts against the stop block 12.

[0050] When the ejector plate 1 pushes upward, the rotating needle 3 and the second ejector rod 10 remain stationary under the elastic force of the second spring 9 until the pressure block 11 abuts against the mounting plate of the second ejector rod 10. During the subsequent ejection process, the ejector plate 1 begins to drive the rotating needle 3 and the second ejector rod 10 to push upward synchronously. When the ejector plate 1 resets, the stop block 12 stops the second ejector rod 10, thereby pushing the rotating needle 3 to reset.

[0051] This utility model, by setting a detachable pressure block 11 and a stop block 12, is used to replace the vulnerable part, namely the rotating needle 3, without disassembling the mold.

[0052] like Figure 9 As shown, the upper end of the rotating needle 3 in this embodiment is conical, and multiple cut surfaces are provided vertically on the conical surface. The material head 100 can wrap around the upper end of the conical rotating needle 3 to ensure that the rotating needle 3 can drive the material head 100 to rotate when it rotates.

[0053] See Figure 6 , Figure 7 and Figure 9 The rotation limiting device includes a limiting bolt 13 and a steel ball 14. The limiting bolt 13 is fixed to the bottom of the rear mold 15 of the injection mold by a fixing block, and the steel ball 14 is disposed at one end of the limiting bolt 13. The side of the rotating needle 3 is provided with a track groove 301, and the steel ball 14 rolls in contact with the track groove 301.

[0054] The track groove 301 includes an upper groove 3011, a lower groove 3012, and an arc-shaped groove 3013 connecting the upper groove 3011 and the lower groove 3012. Both the upper groove 3011 and the lower groove 3012 are arranged parallel to the axis of the rotating needle 3, and are staggered in the circumferential direction of the rotating needle 3. The specific staggered position of the upper groove 3011 and the lower groove 3012 can be determined according to the actual rotation angle of the material head 100.

[0055] As the rotating needle 3 is pushed upward by the ejector plate 1, the steel ball 14, in cooperation with the track groove 301, slides from the upper groove 3011 along the arc-shaped groove 3013 into the lower groove 3012, thereby causing the rotating needle 3 to rotate at a certain angle. The length of the upper groove 3011 is necessary to ensure that the material head 100 can only rotate after it has completely detached from the gate.

[0056] Preferably, the track groove 301 is provided with two centrally symmetrically distributed sections, and the limiting bolts 13 and steel balls 14 are provided with two sets respectively.

[0057] It is worth mentioning that a guide sleeve 16 is also fixed on the rear mold 15 of the injection mold. The guide sleeve 16 is slidably mounted on the rotating needle 3 to ensure smooth rotation.

[0058] In addition, the self-cutting delayed rotation ejection mechanism of the injection mold sprue of this utility model also includes a synchronous delayed ejector pin mechanism.

[0059] See Figure 7 and Figure 10 The synchronous delay ejector mechanism includes a synchronous pin 17 and a third ejector rod 18. The ejector plate 1 has a limiting cavity 101. The lower end of the synchronous pin 17 passes through the limiting cavity 101 and abuts against the upper end of the third ejector rod 18. The upper end of the synchronous pin 17 extends vertically upward through the rear mold 15 and the rear mold core 19 to the gate of the injection mold, located in the middle of the gate. The lower end of the third ejector rod 18 passes through the ejector plate 1 and abuts against the bottom plate 7 of the injection mold. Both the lower end of the synchronous pin 17 and the upper end of the third ejector rod 18 are provided with mounting platforms. In the mold-closed state, the mounting platform at the lower end of the synchronous pin 17 rests against the top wall of the limiting cavity 101.

[0060] When the ejector plate 1 is pushed upward, the synchronizing pin 17 and the third ejector rod 18 remain stationary. Until the bottom wall of the limiting cavity 101 of the ejector plate 1 rests against the mounting platform of the third ejector rod 18, during the subsequent pushing process, the ejector plate 1 begins to drive the synchronizing pin 17 and the third ejector rod 18 to push upward synchronously. When the ejector plate 1 resets, the base plate 7 stops the third ejector rod 18, thereby pushing the synchronizing pin 17 back to its original position.

[0061] It should be noted that the reverse pin 2, rotating pin 3, and synchronizing pin 17 are simultaneously driven by the ejector plate 1 to push the material head 100 upward. By setting the synchronizing pin 17, this utility model makes the force on the material head 100 more even during the upward pushing process, and it is less likely that the material head 100 will be pulled, deformed, or even broken.

[0062] In summary, this utility model, by setting an inverted delayed ejector pin mechanism and a rotary delayed ejector pin mechanism on the rear mold 15, utilizes the delayed ejected inverted pin 2 to hold the material head 100, achieving automatic cutting of the material head 100 from the product. This eliminates the need for manual cutting of the material head 100 using shears, reducing manpower input, improving production efficiency, enabling mass production, and lowering production costs. Simultaneously, the rotary pin 3 allows the material head 100 to adjust its direction during the delayed ejection process, moving it away from the product. This effectively prevents the material head 100 from falling and scratching the product's surface, and facilitates smooth removal by the robotic arm. It is no longer limited by the position and angle of the injection port, enhancing the mold's adaptability to different injection port settings and improving production flexibility.

[0063] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A self-cutting, delayed-rotation ejection mechanism for injection mold sprues, characterized in that, include: The ejector plate (1) and the undercut delayed ejector mechanism and the rotary delayed ejector mechanism are both installed on the ejector plate (1) along the opening and closing direction of the injection mold. The undercut delayed ejector mechanism includes an undercut pin (2) and a first delayed ejection device provided at one end of the undercut pin (2). The other end of the undercut pin (2) is provided with an undercut forming part (201). The sprue (100) formed at the gate position of the injection mold can be formed in the undercut forming part (201) at the opening. There is a backed-out part in the mold closing direction; the rotary delayed ejector mechanism includes a rotary pin (3), a second delayed ejection device disposed at one end of the rotary pin (3), and a rotary limiting device; the ejector plate (1) is used to drive the backed-out pin (2) and the rotary pin (3) to eject the material head (100) in a delayed manner through the first delayed ejection device and the second delayed ejection device, and can force the rotary pin (3) to drive the material head (100) to rotate through the rotary limiting device.

2. The injection mold sprue self-cutting delayed rotary ejection mechanism according to claim 1, characterized in that: The first delayed ejection device includes a first sheath (4), a first spring (5), and a first ejector rod (6). The first sheath (4) is fixed on the ejector plate (1). One end of the underpin (2) passes through the first sheath (4) and abuts against one end of the first ejector rod (6). The other end of the first ejector rod (6) passes through the ejector plate (1) and abuts against the bottom plate (7) of the injection mold. The first spring (5) is fitted on the underpin (2), and the two ends of the first spring (5) elastically abut against the step at one end of the underpin (2) and the top of the first sheath (4), respectively.

3. The injection mold sprue self-cutting delayed rotary ejection mechanism according to claim 1, characterized in that: The undercut forming part (201) is formed by cutting one end of the undercut pin (2). The undercut forming part (201) has two L-shaped cutting surfaces (2011) and the included angle between the two cutting surfaces (2011) is an acute angle.

4. The injection mold sprue self-cutting delayed rotary ejection mechanism according to claim 1, characterized in that: The second delayed ejection device includes a second sheath (8), a second spring (9), and a second ejector rod (10). The second sheath (8) is fixed on the ejector plate (1). One end of the rotating needle (3) passes through the second sheath (8) and abuts against one end of the second ejector rod (10). The second spring (9) is fitted on the rotating needle (3), and the two ends of the second spring (9) elastically abut against the step at one end of the rotating needle (3) and the top of the second sheath (8), respectively.

5. The injection mold sprue self-cutting delayed rotary ejection mechanism according to claim 4, characterized in that: The bottom of the ejector plate (1) is detachably fixed with a pressure block (11) for pressing the second sheath (8), and the bottom plate (7) of the injection mold is detachably fixed with a stop block (12) opposite to the pressure block (11). The other end of the second ejector rod (10) passes through the pressure block (11) and abuts against the stop block (12).

6. The injection mold sprue self-cutting delayed rotary ejection mechanism according to claim 1, characterized in that: The rotation limiting device includes a limiting bolt (13) and a steel ball (14). The limiting bolt (13) is fixed on the rear mold (15) of the injection mold, and the steel ball (14) is disposed at one end of the limiting bolt (13). The side of the rotating needle (3) is provided with a track groove (301), and the steel ball (14) rolls in contact with the track groove (301).

7. The injection mold sprue self-cutting delayed rotary ejection mechanism according to claim 6, characterized in that: The track groove (301) includes an upper groove (3011), a lower groove (3012), and an arc-shaped groove (3013) connecting the upper groove (3011) and the lower groove (3012). The upper groove (3011) and the lower groove (3012) are both arranged parallel to the axis of the rotating needle (3), and the upper groove (3011) and the lower groove (3012) are staggered in the circumferential direction of the rotating needle (3).

8. The injection mold sprue self-cutting delayed rotary ejection mechanism according to claim 6, characterized in that: A guide sleeve (16) is also fixed on the rear mold (15) of the injection mold, and the guide sleeve (16) is slidably fitted on the rotating needle (3).

9. The injection mold sprue self-cutting delayed rotary ejection mechanism according to claim 1, characterized in that: It also includes a synchronous delay ejector mechanism, which includes a synchronous pin (17) and a third ejector rod (18). The ejector plate (1) is provided with a limiting cavity (101). One end of the synchronous pin (17) passes through the limiting cavity (101) and abuts against one end of the third ejector rod (18). The other end of the third ejector rod (18) passes through the ejector plate (1) and abuts against the bottom plate (7) of the injection mold.

10. The injection mold sprue self-cutting delayed rotary ejection mechanism according to claim 1, characterized in that: The reverse pin (2) is located at the end of the material head (100) that is connected to the product.

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