Injection mold and injection molding method for cylindrical product with inverted buckle

Abstract

The injection mold comprises a front mold body, a rear mold body and a mold core, a rear mold plate and a rear mold fixing plate are arranged in a separable mode, an elastic piece is arranged between the rear mold plate and the rear mold fixing plate, and the injection mold further comprises a first lateral core pulling assembly, a static mold insert and a movable mold insert; a core cylinder of the first lateral core pulling assembly is arranged on the periphery of a core shaft in a sleeving mode, a cylindrical forming cavity is formed by the core cylinder and the core shaft, the front end of a static mold insert is limited on a front mold core, the rear end of the static mold insert penetrates through the core cylinder to enter the cylindrical forming cavity, and the rear end of a movable mold insert is limited on a rear mold fixing plate. The front end of the core cylinder sequentially penetrates through the rear mold plate, the rear mold core and the core cylinder to enter the cylindrical forming cavity; and the rear end of the static mold insert and the front end of the movable mold insert jointly form an inverted buckle forming part in the cylindrical forming cavity. The smoothness of the periphery of the cylindrical part is ensured; and normal mold opening of the mold is ensured.

Description

Technical Field

[0001] The invention relates to the field of mold injection, and in particular to an injection mold and an injection method for an undercut tubular product. Background Art

[0002] Injection molding is a processing method used in mass production of certain parts. The specific steps are to inject the heated and molten material into the mold cavity by high pressure, and obtain the molded product after cooling and solidification. The injection mold is the tool used for injection molding. This tool is composed of various parts. Different molds are composed of different parts. It mainly realizes the processing of the shape of the object by changing the physical state of the molded material. The molding and processing of product components in modern manufacturing industry almost all need to be completed by using molds.

[0003] In the prior art, for the injection molding method of a cylindrical product with an undercut (i.e., an undercut is formed on the cylindrical portion of the product), generally, a molding cavity of the cylindrical portion (i.e., a cylindrical molding cavity) is obtained by splicing two front and rear molding inserts; although the product can be obtained, the parting surface of the mold is distributed along the length direction of the cylindrical portion, and after injection molding, both sides of the cylindrical portion have flash along its axial direction, which requires subsequent removal and grinding, etc., which is cumbersome to operate and has a high cost. Summary of the invention

[0004] To this end, the present invention provides an injection mold and an injection molding method for the above-mentioned cylindrical product with undercuts, so as to avoid flash along the axial direction after injection molding.

[0005] To achieve the above purpose, the technical solution provided by the present invention is as follows:

[0006] An injection mold for a cylindrical product with an undercut, comprising a front mold, a rear mold and a mold core, wherein the mold core comprises a front mold core arranged on the front mold and a rear mold core arranged on the rear mold; when the front mold and the rear mold are closed, the front mold core and the rear mold core enclose a molding cavity; the rear mold comprises a rear mold plate and a rear mold fixing plate, wherein the rear mold plate and the rear mold fixing plate can be separated and an elastic member is arranged between the two; further comprising a first lateral core pulling assembly, a static mold insert and a dynamic mold insert, wherein the first lateral core pulling assembly comprises a first core pulling slider with and a core shaft and a core barrel which are assembled on the first core-pulling slider and inserted into the molding cavity, the core barrel is sleeved on the outer circumference of the core shaft and together constitute a cylindrical molding cavity; the front end of the static mold insert is restricted on the front mold core, and its rear end passes through the core barrel and enters the cylindrical molding cavity; the rear end of the dynamic mold insert is restricted on the rear mold fixing plate, and its front end passes through the rear mold plate, the rear mold core and the core barrel in turn and enters the cylindrical molding cavity; the rear end of the static mold insert and the front end of the dynamic mold insert together constitute an undercut molding portion in the cylindrical molding cavity.

[0007] Furthermore, a limiting member is provided between the rear template and the rear template fixing plate to limit the maximum distance of separation between the rear template and the rear template fixing plate.

[0008] Furthermore, the limiting member is a limiting bolt, which passes through the rear mold fixing plate and is screwed and fixed on the rear mold. The rear mold fixing plate is provided with an abutment recess. When the rear mold fixing plate is in affixed with the rear mold, the abutment recess and the nut of the limiting bolt are spaced apart. When the rear mold and the rear mold fixing plate are separated until the nut of the limiting bolt abuts against the abutment recess, it is restricted.

[0009] Furthermore, the elastic member is a spring, and the spring is sleeved on the limiting bolt.

[0010] Furthermore, the rear end of the static mold insert and the front end of the dynamic mold insert both have semicircular recesses. When the molds are closed, the rear end of the static mold insert abuts against the front end of the dynamic mold insert; the two semicircular recesses form an undercut molding portion.

[0011] Furthermore, it also includes a first driving cylinder, which is connected to the first core-pulling slider to drive the first core-pulling slider to slide.

[0012] Furthermore, it also includes a second lateral core pulling assembly, which includes a second core pulling slider, a core pulling insert, a shovel base, a first molding insert and a second molding insert, the first molding insert and the second molding insert are arranged opposite to each other, the core pulling insert passes through the second core pulling slider, and the inner ends of the core pulling insert respectively form an oblique guide with the first molding insert and the second molding insert; the outer end of the core pulling insert cooperates with the shovel base, and the shovel base is fixed on the front mold; when the front mold and the rear mold are closed, the core pulling insert is driven to move inward, thereby driving the first molding insert and the second molding insert away from each other; when the front mold and the rear mold are opened, the core pulling insert is driven to move outward, thereby driving the first molding insert and the second molding insert close to each other.

[0013] Furthermore, it also includes a second driving cylinder, which is connected to the second core-pulling slider to drive the second core-pulling slider to slide.

[0014] A method for injection molding a cylindrical product with an undercut comprises the following steps:

[0015] S1, providing the injection mold of the cylindrical product with undercut as described above, closing the front mold and the rear mold in place, and performing injection molding, wherein the core barrel and the core shaft form a cylindrical molding cavity to form the cylindrical part of the product, and the undercut molding part formed by the rear end of the static mold insert and the front end of the dynamic mold insert is used for the undercut on the cylindrical part of the molded product;

[0016] S2, after the product is cooled and formed, the mold begins to be opened. In the initial stage, the rear mold plate and the rear mold fixing plate are separated under the action of the elastic member, so that the front end of the movable mold insert is pulled out from the core barrel;

[0017] S3, after which the front mold and the rear mold plate of the rear mold begin to separate, thereby driving the rear end of the static mold insert to be pulled out of the core barrel;

[0018] S4, the first lateral core pulling assembly is pulled out laterally to achieve lateral core pulling;

[0019] S5, eject the product and complete demoulding.

[0020] The technical solution provided by the present invention has the following beneficial effects:

[0021] By designing a structure in which the core barrel is sleeved on the outer periphery of the core shaft and together constitutes a cylindrical molding cavity, the cylindrical molding cavity has no parting surface extending along its axial direction, and no flash extending along the axial direction of the cylindrical part will appear after injection molding; the smoothness of the outer periphery of the cylindrical part is ensured; the undercut of the cylindrical part is composed of a static mold insert and a dynamic mold insert inserted into the core barrel, thereby realizing the molding of the undercut.

[0022] At the same time, the front end of the static mold insert is restricted on the front mold core, and the rear end of the dynamic mold insert is restricted on the rear mold fixing plate. The rear mold plate and the rear mold fixing plate can be separated and an elastic member is arranged between the two. When opening the mold, the rear mold plate and the rear mold fixing plate will be separated first under the action of the elastic member, thereby driving the dynamic mold insert to be pulled out of the core barrel. Afterwards, the separation of the rear mold plates of the front mold and the rear mold will synchronously drive the static mold insert to be pulled out of the core barrel. In this way, the first lateral core pulling assembly can be smoothly pulled out, ensuring the normal opening of the mold, and the structural design is ingenious and simple. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Shown is a front view of an injection mold for a cylindrical product with undercuts in an embodiment;

[0024] Figure 2 Shown Figure 1 Sectional view along line AA;

[0025] Figure 3 Shown Figure 2 Enlarged schematic diagram of the middle C area;

[0026] Figure 4 Shown Figure 1 Sectional view along the midline BB;

[0027] Figure 5 Shown Figure 4 A magnified schematic diagram of the middle D area;

[0028] Figure 6The figure shows an assembly diagram of the first lateral core pulling assembly, the static mold insert and the dynamic mold insert in the embodiment;

[0029] Figure 7 Shown Figure 6 A schematic diagram of a partial structural breakdown of the structure shown;

[0030] Figure 8 The figure shows an assembly diagram of the second lateral core pulling assembly in the embodiment;

[0031] Fig. 9 It is a partial structural exploded schematic diagram of the second lateral core pulling assembly in the embodiment;

[0032] Fig.10 Shown is a cross-sectional view of the injection mold of the cylindrical product with undercuts in another direction in the embodiment. DETAILED DESCRIPTION

[0033] To further illustrate the various embodiments, the present invention provides drawings. These drawings are part of the disclosure of the present invention, which are mainly used to illustrate the embodiments and can be used in conjunction with the relevant descriptions in the specification to explain the operating principles of the embodiments. With reference to these contents, a person of ordinary skill in the art should be able to understand other possible implementations and advantages of the present invention. The components in the figures are not drawn to scale, and similar component symbols are generally used to represent similar components.

[0034] In the description of the present invention, terms such as "up", "down", "left", "right", "front", "back", etc., and the orientation or position relationship are based on the orientation or position relationship shown in the drawings, and are only for the convenience of description and simplification of operation, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention.

[0035] The present invention will now be further described with reference to the accompanying drawings and specific implementation methods.

[0036] Reference Figures 1 to 10 As shown, the present embodiment provides an injection mold for a cylindrical product with an undercut, comprising a front mold 1, a rear mold 2 and a mold core, wherein the mold core comprises a front mold core 5 arranged on the front mold 1 and a rear mold core 6 arranged on the rear mold 2; when the front mold 1 and the rear mold 2 are molded together, the front mold core 5 and the rear mold core 6 enclose a molding cavity 100. The rear mold 2 comprises a rear mold plate 3 and a rear mold fixing plate 4, wherein the rear mold plate 3 and the rear mold fixing plate 4 are detachably arranged and an elastic member 31 is arranged between the two; the arrangement of the elastic member 31 can drive the rear mold plate 3 and the rear mold fixing plate 4 to separate from each other; specifically, the rear mold core 6 is assembled on the rear mold plate 3.

[0037] It also includes a first lateral core pulling assembly, a static mold insert 15 and a dynamic mold insert 16. The first lateral core pulling assembly includes a first core pulling slider 11 and a core shaft 12 and a core barrel 13 assembled on the first core pulling slider 11 and inserted into the molding cavity. Specifically, the first core pulling slider 11 is slidably arranged on the rear mold plate 3, and the core barrel 13 is sleeved on the outer periphery of the core shaft 12 and together constitute a cylindrical molding cavity 101; specifically, the cylindrical molding cavity 101 is jointly constituted by the outer peripheral surface of the core shaft 12 and the inner wall surface of the core barrel 13, and the cylindrical molding cavity 101 is used to mold the cylindrical part of the product.

[0038] The front end of the static mold insert 15 is restricted on the front mold core 5, and its rear end passes through the core barrel 13 to enter the cylindrical molding cavity 101. The static mold insert 15 moves synchronously with the front mold 1 and the front mold core 5; the rear end of the movable mold insert 16 is restricted on the rear mold fixing plate 4, and its front end passes through the rear mold plate 3, the rear mold core 6 and the core barrel 13 in sequence to enter the cylindrical molding cavity 101; the rear end of the static mold insert 15 and the front end of the movable mold insert 16 together form an undercut molding portion 102 in the cylindrical molding cavity 101. In this specific embodiment, the rear end of the static mold insert 15 and the front end of the movable mold insert 16 both have semicircular recesses 151 and 161, and the inner walls of the semicircular recesses 151 and 161 have a concave-convex structure. When the mold is closed, the rear end of the static mold insert 15 and the front end of the movable mold insert 16 are in contact with each other; the two semicircular recesses 151 and 161 form an undercut molding portion 102.

[0039] This embodiment also provides an injection molding method for a cylindrical product with an undercut, comprising the following steps:

[0040] S1, provide an injection mold for the above-mentioned cylindrical product with undercut, close the front mold 1 and the rear mold 2 in place, and perform injection molding, the cylindrical part of the product is formed by the cylindrical molding cavity 101 composed of the core barrel 13 and the core shaft 12, and the undercut molding part 102 formed by the rear end of the static mold insert 15 and the front end of the dynamic mold insert 16 is used for the undercut on the cylindrical part of the molded product.

[0041] Specifically, when the front mold 1 and the rear mold 2 are in place, the rear mold plate 3 and the rear mold fixing plate 4 are in contact with each other, and the elastic member 31 is compressed to store energy.

[0042] S2, after the product is cooled and formed, the mold is opened. In the initial stage, the rear mold plate 3 and the rear mold fixing plate 4 are separated under the action of the elastic member 31, so that the front end of the movable mold insert 16 is pulled out from the core barrel 13; in this way, the movable mold insert 16 will not affect the core barrel 13.

[0043] S3, after that, the front mold 1 and the rear mold plate 3 of the rear mold 2 begin to separate, thereby driving the rear end of the static mold insert 15 to be pulled out from the core barrel 13; in this way, the static mold insert 15 will not affect the core barrel 13.

[0044] S4, the first lateral core pulling assembly is pulled out laterally to realize lateral core pulling; the core barrel 13 and the core shaft 12 are separated from the cylindrical part of the product.

[0045] S5, ejecting the product to complete demoulding. Specifically, this step is to eject the product forward by the ejector pin of the rear mold 2.

[0046] By designing the core barrel 13 to be sleeved on the outer periphery of the core shaft 12 and together forming the structure of the cylindrical molding cavity 101, the cylindrical molding cavity 101 has no parting surface extending along its axial direction, and no flash extending along the axial direction of the cylindrical part will appear after injection molding; the smoothness of the outer periphery of the cylindrical part is ensured; the undercut of the cylindrical part is composed of a static mold insert 15 and a dynamic mold insert 16 inserted into the core barrel 13, thereby realizing the molding of the undercut.

[0047] At the same time, the front end of the static mold insert 15 is restricted on the front mold core 5, and the rear end of the dynamic mold insert 16 is restricted on the rear mold fixing plate 4. The rear mold plate 3 and the rear mold fixing plate 4 can be separated and an elastic member 31 is arranged between the two. When opening the mold, the rear mold plate 3 and the rear mold fixing plate 4 will be separated first under the action of the elastic member 31, thereby driving the dynamic mold insert 16 to be pulled out of the core barrel 13. Afterwards, the separation of the rear mold plate 3 of the front mold 1 and the rear mold 2 will synchronously drive the static mold insert 15 to be pulled out of the core barrel 13. In this way, the first lateral core pulling assembly can be smoothly pulled out, ensuring the normal mold opening of the mold, and the structural design is ingenious and simple.

[0048] Furthermore, in this embodiment, a limiting member 32 is provided between the rear mold plate 3 and the rear mold fixing plate 4 to limit the maximum distance of separation between the rear mold plate 3 and the rear mold fixing plate 4, thereby ensuring accurate mold opening of the mold. Specifically, the maximum distance of separation between the rear mold plate 3 and the rear mold fixing plate 4 needs to be no less than the travel distance of the rear end of the movable mold insert 16 to withdraw the core barrel 13.

[0049] Specifically, the limiting member 32 is a limiting bolt, which passes through the rear mold fixing plate 4 and is screwed and fixed on the rear mold plate 3. The rear mold fixing plate 4 is provided with an abutment recess 33. When the rear mold fixing plate 4 is in contact with the rear mold plate 3, the abutment recess 33 and the nut of the limiting bolt are spaced apart. When the rear mold plate 3 and the rear mold fixing plate 4 are separated until the nut of the limiting bolt abuts against the abutment recess 33, the limiting bolt is restricted.

[0050] The elastic member 31 is a spring, and the spring is sleeved on the limiting bolt to achieve stable assembly of the elastic member.

[0051] The above structure can well realize the limitation between the rear mold plate 3 and the rear mold fixing plate 4 and the assembly of the elastic member 31. The matching structure of the limit bolt and the elastic member 31 can be set in multiple groups, such as setting four groups respectively distributed at four end angle positions, etc., to achieve uniform force. Of course, in other embodiments, it is not limited to this. For example, the limitation of the rear mold plate 3 and the rear mold fixing plate 4 can be realized by an external limit device, and the elastic member 31 can also be a spring sheet, etc.

[0052] Furthermore, it also includes a first driving cylinder 14, which is connected to the first core pulling slider 11 to drive the first core pulling slider 11 to slide, that is, in step S4, the first core pulling slider 11 is driven to be pulled out by the first driving cylinder 14, so that the first lateral core pulling assembly is pulled out laterally; similarly, when closing the mold, the first core pulling slider 11 is driven to slide by the first driving cylinder 14 until the mold closing is completed.

[0053] Furthermore, in this embodiment, the injection mold further includes a second lateral core pulling assembly, which includes a second core pulling slider 21, a core pulling insert 22, a shovel base 25, a first molding insert 23 and a second molding insert 24, wherein the first molding insert 23 and the second molding insert 24 are arranged opposite to each other, the core pulling insert 22 passes through the second core pulling slider 21, and the inner ends of the core pulling insert 22 respectively form an oblique guide fit with the first molding insert 23 and the second molding insert 24; the outer ends of the core pulling insert 22 and the shovel base 25 are connected to each other. The shovel base 25 is fixed on the front mold 1; when the front mold 1 and the rear mold 2 are closed, the core-pulling insert 22 is driven to move inward, and then the first molding insert 23 and the second molding insert 24 are driven to move away from each other, thereby increasing the distance between the first molding insert 23 and the second molding insert 24. At this time, the first molding insert 23 and the second molding insert 24 participate in the molding of the product. Furthermore, the first molding insert 23 and the second molding insert 24 are provided with an undercut molding part 28 for forming an undercut at another position of the molding product. After the product is formed, the inner wall of the product will fit the surface of the first molding insert 23 and the second molding insert 24. When the front mold 1 and the rear mold 2 are opened (such as step S3), the core-pulling insert 22 is driven to move outward, and then the first molding insert 23 and the second molding insert 24 are driven to move closer to each other, so that the undercut molding part 28 of the first molding insert 23 and the second molding insert 24 can be separated from the product first. Afterwards, the second core-pulling slider 21, the core-pulling insert 22, the first molding insert 23 and the second molding insert 24 are uniformly pulled outward. The first molding insert 23 and the second molding insert 24 are separated from the inner wall of the product in advance to effectively avoid damage to the product and damage caused by undercutting due to too firm connection during core pulling.

[0054] Specifically, one embodiment is as follows: a molding block 27 is fixed on the inner side of the second core-pulling slider 21, and the molding block 27 has a vertically penetrating channel, and the first molding insert 23 and the second molding insert 24 are arranged in the channel of the molding block 27; when the mold is closed, the first molding insert 23 and the second molding insert 24 move away from each other until the surface is flush with the surface of the molding block 27, so as to jointly form a molding surface; after the injection molding is completed, the first molding insert 23 and the second molding insert 24 are separated from the inner wall of the product first, and the undercut molding part 28 of the first molding insert 23 and the second molding insert 24 is separated first, which is conducive to the subsequent smooth core pulling. It is very suitable for the injection molding of products with a concave cavity and an undercut arranged in the concave cavity.

[0055] Furthermore, it also includes a second driving cylinder 26, which is connected to the second core-pulling slider 21 to drive the second core-pulling slider 21 to slide, that is, in step S4, the second core-pulling slider 21 is driven to be pulled out by the second driving cylinder 26; similarly, when closing the mold, the second core-pulling slider 21 is driven to slide by the second driving cylinder 26 until the mold closing is completed.

[0056] Of course, in other embodiments, when the product does not have undercuts at other positions, the structure of the second lateral core pulling assembly may not be used.

[0057] Although the present invention has been specifically shown and described in conjunction with the preferred embodiments, it should be understood by those skilled in the art that various changes may be made to the present invention in form and details without departing from the spirit and scope of the present invention as defined by the appended claims, all of which are within the scope of protection of the present invention.

Claims

1. An injection mold for a cylindrical product with an undercut, comprising a front mold, a rear mold and a mold core, wherein the mold core comprises a front mold core arranged on the front mold and a rear mold core arranged on the rear mold; when the front mold and the rear mold are closed, the front mold core and the rear mold core enclose a molding cavity; characterized in that: The rear mold includes a rear mold plate and a rear mold fixing plate, which can be separated and an elastic member is arranged between the two; it also includes a first lateral core pulling assembly, a static mold insert and a dynamic mold insert, the first lateral core pulling assembly includes a first core pulling slider and a core shaft and a core barrel assembled on the first core pulling slider and inserted into the molding cavity, the core barrel is sleeved on the outer circumference of the core shaft and together constitute a cylindrical molding cavity; the front end of the static mold insert is restricted on the front mold core, and the rear end thereof passes through the core barrel to enter the cylindrical molding cavity, and the rear end of the dynamic mold insert is restricted on the rear mold fixing plate, and the front end thereof passes through the rear mold plate, the rear mold core and the core barrel in turn to enter the cylindrical molding cavity; the rear end of the static mold insert and the front end of the dynamic mold insert together constitute an undercut molding portion in the cylindrical molding cavity.

2. The injection mold for the undercut tubular product according to claim 1, characterized in that: A limiting member is also provided between the rear template and the rear template fixing plate to limit the maximum distance of separation between the rear template and the rear template fixing plate.

3. The injection mold for the undercut tubular product according to claim 2, characterized in that: The limiting part is a limiting bolt, which passes through the rear mold fixing plate and is screwed and fixed on the rear mold. The rear mold fixing plate is provided with an abutment recess. When the rear mold fixing plate is in contact with the rear mold, the abutment recess and the nut of the limiting bolt are spaced apart. When the rear mold and the rear mold fixing plate are separated until the nut of the limiting bolt abuts against the abutment recess, it is restricted.

4. The injection mold for the undercut tubular product according to claim 3, characterized in that: The elastic member is a spring, and the spring is sleeved on the limiting bolt.

5. The injection mold for the undercut tubular product according to claim 1, characterized in that: The rear end of the static mold insert and the front end of the dynamic mold insert both have semicircular recesses. When the molds are closed, the rear end of the static mold insert abuts against the front end of the dynamic mold insert; the two semicircular recesses form an undercut molding part.

6. The injection mold for a cylindrical product with an undercut according to claim 1, characterized in that: It also includes a first driving cylinder, which is connected to the first core-pulling slider to drive the first core-pulling slider to slide.

7. The injection mold for a cylindrical product with undercut according to claim 1, characterized in that: It also includes a second lateral core pulling assembly, which includes a second core pulling slider, a core pulling insert, a shovel base, a first molding insert and a second molding insert. The first molding insert and the second molding insert are arranged opposite to each other, and the core pulling insert passes through the second core pulling slider. The inner ends of the core pulling insert respectively form an oblique guide with the first molding insert and the second molding insert; the outer end of the core pulling insert cooperates with the shovel base, and the shovel base is fixed on the front mold; when the front mold and the rear mold are closed, the core pulling insert is driven to move inward, thereby driving the first molding insert and the second molding insert away from each other; when the front mold and the rear mold are opened, the core pulling insert is driven to move outward, thereby driving the first molding insert and the second molding insert close to each other.

8. The injection mold for the undercut tubular product according to claim 7, characterized in that: It also includes a second driving oil cylinder, which is connected to the second core-pulling slider to drive the second core-pulling slider to slide.

9. A method for injection molding a cylindrical product with an undercut, characterized in that: The steps include: S1, providing an injection mold for a cylindrical product with an undercut according to any one of claims 1 to 8, closing the front mold and the rear mold in place, and performing injection molding, wherein the core barrel and the core shaft form a cylindrical portion of the product in a cylindrical molding cavity, and the undercut molding portion formed by the rear end of the static mold insert and the front end of the dynamic mold insert is used for the undercut on the cylindrical portion of the molded product; S2, after the product is cooled and formed, the mold begins to be opened. In the initial stage, the rear mold plate and the rear mold fixing plate are separated under the action of the elastic member, so that the front end of the movable mold insert is pulled out from the core barrel; S3, after which the front mold and the rear mold plate of the rear mold begin to separate, thereby driving the rear end of the static mold insert to be pulled out of the core barrel; S4, the first lateral core pulling assembly is pulled out laterally to achieve lateral core pulling; S5, eject the product and complete demoulding.

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