Method and mold for forming a porous rubber part

Abstract

A porous rubber part forming method comprises a preforming S1, providing a volume-fixed glue storage space, filling glue material in the glue storage space, and forming a preforming hole in the glue material after heating and softening the glue material; a second forming S2, placing an insert needle in the preforming hole, the insert needle matching the size and shape of the forming hole, and applying pressure to the glue material in the glue storage space by using a molding process to make the glue material adhere to the outer wall of the insert needle; and a demolding forming S3, removing the insert needle to form a porous rubber part after vulcanization of the glue material. The forming method and the mold provided by the application adopt a two-stage forming method, preforming is performed by using a rough insert needle, and vulcanization forming is performed by using a forming insert needle, the rough insert needle and the forming insert needle are designed with equal volumes, and bending or fracture of the forming insert needle caused by extrusion of the glue material can be avoided.

Description

Technical Field

[0001] This invention relates to the field of vulcanization molding process and molding die for rubber parts, specifically to a method and mold for molding porous rubber parts. Background Technology

[0002] In some finished rubber parts, there are multiple holes distributed in the rubber, resembling an inverted gourd or an inverted cone shape. For example... Figure 1 As shown, the rubber part has multiple molding holes 200 distributed in a dense manner, with small spacing between them and a large aspect ratio. The inner diameter of the molding hole 200 gradually decreases from the top to the bottom, with a larger inner diameter at the top and a concave arc-shaped sidewall. Generally, this type of porous rubber part is molded using a compression molding method, where inserts are embedded in the molding die, and the inserts are removed after molding to form the holes. However, due to the large aspect ratio and very small bottom inner diameter of the molding holes 200, and their dense distribution within a single rubber part, if inserts matching the molding holes 200 are used for one-time molding, the inserts will be squeezed by the rubber material after being embedded in the die. Inserts with large aspect ratios often break, leading to molding failure. Therefore, improved molding methods and molds are needed for the production of this type of porous rubber part with a large aspect ratio. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a method for molding porous rubber parts, comprising the following steps:

[0004] Pre-forming S1 provides a fixed-volume storage space for adhesive, which is filled with adhesive. After the adhesive is heated and softened, a pre-formed hole is formed in the adhesive. The cross-section of the pre-formed hole has a dividing interface. Above the dividing interface, the inner diameter of the pre-formed hole is smaller than the inner diameter of the formed hole, and below the dividing interface, the inner diameter of the pre-formed hole is larger than the inner diameter of the formed hole. The volume of the pre-formed hole is the same as that of the formed hole.

[0005] In the second stage of molding S2, a pin is placed in the pre-formed hole. The pin's shape and size match the molding hole. A molding process is used to apply pressure to the adhesive in the storage space, so that the adhesive adheres to the outer wall of the pin.

[0006] Demolding and forming S3, after the rubber material is vulcanized, the inserts are removed to form a porous rubber part.

[0007] Furthermore, the inner wall of the preformed hole has a draft taper.

[0008] Furthermore, the bottom of the preformed hole is an arc-shaped bottom surface.

[0009] Furthermore, the depth of the pre-formed hole is not less than the depth of the formed hole.

[0010] Furthermore, the inner wall below the interface of the preformed hole is a concave arc surface or a stepped surface.

[0011] Furthermore, the preforming step S1 also includes the following steps:

[0012] Place the pre-formed insert S11 in the glue material in the glue storage space. The volume of the part of the pre-formed insert extending into the glue storage space is the same as that of the insert extending into the glue storage space. The outer dimensions of the pre-formed insert match the pre-formed hole. Apply pressure to the glue material in the glue storage space using a molding process to make the glue material adhere to the outer wall of the pre-formed insert.

[0013] Pre-forming demolding S12: Remove the pre-forming inserts to form pre-forming holes.

[0014] A porous rubber part molding die is also proposed, including a middle template with a cavity for receiving rubber material, and a pin plate. The bottom surface of the pin plate can be connected to pre-formed pins or pins. After the pin plate is covered on the middle template, the volume of the pre-formed pins or pins extending into the cavity is the same.

[0015] Furthermore, the insert plate has a through-hole for excess adhesive.

[0016] Furthermore, the bottom end of the overflow hole has a tapered guide hole.

[0017] Furthermore, it also includes a fixing plate that covers the pin plate, and a glue guiding hole is provided on the fixing plate. When the fixing plate covers the pin plate, the glue guiding hole and the glue overflow hole are connected to form a glue overflow channel. The inner diameter of the glue overflow channel gradually increases from the tapered guide hole upwards. A glue storage tank that communicates with the top of the glue overflow channel is also provided on the upper surface of the fixing plate. A top template is covered on the top of the fixing plate, and a bottom template is connected below the middle template.

[0018] Compared with the prior art, the technical solution of this application has the following beneficial effects: The molding method and mold proposed in this invention adopt a two-stage molding method. First, a coarse insert is used for pre-forming, and then a molding insert is used for vulcanization molding. The coarse insert and the molding insert are designed with equal volume, which can avoid the molding insert from bending or breaking due to the extrusion of rubber material. Attached Figure Description

[0019] Figure 1 : Cross-sectional view of a porous rubber component;

[0020] Figure 2 : Schematic diagram of the molding process for porous rubber parts;

[0021] Figure 3 : Schematic diagram of the forming steps of preformed holes;

[0022] Figure 4 : Schematic diagram of the overall structure of the molding die;

[0023] Figure 5 Schematic diagram of the split structure of the molding die;

[0024] Figure 6 : A cross-sectional view of the pin plate connecting the pre-formed pins;

[0025] Figure 7 : A cross-sectional view of the pin plate connecting the pins;

[0026] Figure 8 : A partially enlarged structural diagram of the overflow hole. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] A method for molding porous rubber parts includes the following steps:

[0029] Pre-forming S1 provides a fixed-volume storage space K for adhesive, which is filled with adhesive material. After the adhesive material is heated and softened, a pre-formed hole 100 is formed in the adhesive material. The pre-formed hole 100 has a cross-section with a dividing interface 101. Above the dividing interface 101, the inner diameter of the pre-formed hole 100 is smaller than the inner diameter of the formed hole 200, and below the dividing interface 101, the inner diameter of the pre-formed hole 100 is larger than the inner diameter of the formed hole 200. The volume of the pre-formed hole 100 is the same as that of the formed hole 200.

[0030] In the second stage of molding S2, a pin 300 is placed in the pre-forming hole 100. The outer dimensions of the pin 300 match those of the forming hole 200. Pressure is applied to the adhesive material in the adhesive storage space K using a molding process, so that the adhesive material adheres to the outer wall of the pin 300.

[0031] Demolding and forming S3, after the rubber material cools, removing the insert 300 forms a porous rubber part.

[0032] The above constitutes the basic steps of the molding method proposed in this invention, among which the pre-forming step S1 is particularly crucial. Specifically, as follows... Figure 1 and Figure 2As shown, the pre-forming hole 100 and the forming hole 200 have the same volume. Since the pre-forming hole 100 is divided into two segments by the interface 101, the upper segment has a smaller inner diameter than the forming hole 200, while the lower segment has a larger inner diameter. In short, the pre-forming hole 100 has a smaller length-to-diameter ratio than the forming hole 200, and its inner diameter changes more uniformly. When the pre-forming hole 100 is in place, the forming of the forming hole 200 reduces the pressure of the rubber material on the insert pin 300, thus preventing the insert pin 300 from being squeezed and broken. When the insert pin 300 is gradually placed into the pre-forming hole 100, before it contacts the interface 101, the first half of the insert pin 300 enters the pre-forming hole 100 freely and does not squeeze against the rubber material. As the insert pin 300 continues to be placed downwards, the sidewalls of the insert pin 300 squeeze against the rubber material at the interface 101. Figure 2 The extrusion area is visible at the solid filling point. Since the volume of the glue storage space K is fixed, and the insert pin 300 has the same dimensions and form hole 200 as the pre-formed hole 100, during the extrusion of the glue, the glue is squeezed and flows to the side wall of the insert pin 300. That is, the empty area below the interface 101 after the insert pin 300 enters the pre-formed hole 100 will be gradually filled by the extruded and flowing glue. Finally, when the insert pin 300 is withdrawn, the required form hole 200 is formed.

[0033] The forming of preform S1 can be performed using similar steps to the forming of forming hole 100, see details below. Figure 3 :

[0034] Placement of pre-formed inserts S11: Pre-formed inserts 400 are placed in the adhesive material in the adhesive storage space K. The volume of the portion of the pre-formed insert 400 extending into the adhesive storage space K is the same as that of the portion of insert 300 extending into the adhesive storage space K. The external dimensions of the pre-formed insert 400 match the pre-formed hole 100. Pressure is applied to the adhesive material in the adhesive storage space K using a molding process, causing the adhesive material to adhere to the outer wall of the pre-formed insert 400. Pre-molding S12: Pre-formed insert 400 is removed to form the pre-formed hole 100. Since the length-to-diameter ratio of the pre-formed hole 100 is smaller than that of the formed hole 100, the overall outer diameter of the pre-formed insert 400 is larger than that of insert 300, except that the outer diameter of the upper half corresponding to the interface 101 is smaller than that of insert 300. Figure 3 It is evident that the preformed insert 400 is a coarser insert with a nearly uniform outer diameter compared to insert 300. Therefore, when inserted into the rubber compound, its compressive strength is better than that of insert 400, and it will not break due to the compression of the rubber compound.

[0035] It should be noted that, in general, in addition to using a similar process to forming the pre-formed hole 200, other common processes such as injection molding can also be used to achieve this. The key point of this embodiment is that the volume of the pre-formed hole 100 after forming is the same as that of the formed hole 200 and has the aforementioned interface 101.

[0036] In a more preferred embodiment, the inner wall of the preformed hole 100 has a draft taper to make it easier to demold the preformed insert 400.

[0037] In a more preferred embodiment, the bottom of the preformed hole 100 is an arc-shaped bottom surface. The function of the arc-shaped bottom surface is, on the one hand, to facilitate the separation between the bottom of the preformed hole 100 and the preformed insert 400, and on the other hand, to facilitate the smoother flow of the adhesive material at the bottom surface after being squeezed and adhering to the side wall of the insert 300.

[0038] In a more preferred embodiment, the depth of the pre-formed hole 100 is not less than the depth of the forming hole 200. Generally, it is more preferable that the depth of the pre-formed hole 100 is greater than the depth of the forming hole 200, because this prevents the small end of the insert pin 300 from making extrusive contact with the adhesive material at the bottom of the pre-formed hole 100 after it is inserted. It should be noted that this is not mandatory. If the depth of the pre-formed hole 100 is less than the depth of the forming hole 200, even if the insert pin 300 makes extrusive contact with the adhesive material at the bottom of the pre-formed hole 100, the contact pressure and the volume of the adhesive material will be much smaller than when there is no pre-formed hole 100, which still has a positive effect on preventing the insert pin 300 from breaking. In this embodiment, the depth of the pre-formed hole 100 is equal to the depth of the forming hole 200. That is, the insert pin 300 and the bottom of the pre-formed hole 100 will not be compressed, but will make slight contact.

[0039] In a more preferred embodiment, the inner wall below the interface 101 of the preformed hole 100 is a concave arc surface or a stepped surface. This portion of the inner wall and the insert 300 are initially an empty area without adhesive filling during the initial stage of adhesive extrusion. After extrusion, it gradually flows and adheres to the side wall of the insert 300. The concave arc surface or stepped surface of the inner wall below the interface 101 reduces the distance between this portion and the side wall of the insert 300, and the smoother transition makes the flow and adhesion of this portion of the extruded adhesive more efficient.

[0040] Another embodiment proposes a porous rubber part molding die for the above-described implementation method, which can be found in [reference needed]. Figure 6 and Figure 7It includes a middle template 1, which has a cavity 11 for accommodating the adhesive material, and a pin plate 2. The bottom surface of the pin plate 2 can be connected to a pre-formed pin 400 or a pin 300. After the pin plate 2 is covered on the middle template 1, the volume of the pre-formed pin 400 or pin 300 extending into the cavity 11 is the same.

[0041] After the insert plate 2 is placed over the middle mold plate 1, the cavity 11 is completely sealed. The extruded material will flow evenly to adhere to the pre-formed inserts 400 or 300, forming a pre-formed hole 100 or a formed hole 200. It is understood that when a pre-formed hole 100 needs to be formed, the bottom surface of the insert plate 2 can be connected to the pre-formed insert 400. After the pre-formed insert 400 is removed from the mold along with the insert plate 2, the pre-formed hole 100 is formed. Subsequently, the formed insert 400 is connected to the bottom surface of the insert plate 2, and the same steps are followed to form the formed hole 200 through secondary molding. Specifically, the pre-formed inserts 400 and 300 connected to the insert plate 2 can be interchangeable; either the pre-formed insert 400 or 300 can be connected to the bottom surface of the insert plate 2 as needed. Alternatively, the insert plate 2 can be divided into two parts, one connecting to the pre-formed insert 400 and the other connecting to the insert 300. One part can be selected and fitted onto the middle template 1 as needed. Clearly, when there are many holes, replacing the entire insert plate 2 is more reasonable, avoiding the cumbersome process of replacing the pre-formed insert 400 or insert 300 individually.

[0042] In a more preferred embodiment, the insert plate 2 has a through-hole 31 for excess adhesive. The excess adhesive can be discharged through the overflow hole 31 after the insert plate 2 is closed over the middle template 1.

[0043] In a more preferred embodiment, the bottom end of the overflow hole 31 has a tapered guide hole 311. The tapered guide hole 311 is as follows: Figure 8 As shown, the cross-section is an inverted frustum shape, which allows the extruded adhesive material near the bottom of the overflow hole 31 to be guided from the conical guide hole 311 into the overflow hole 31 and finally discharged.

[0044] In a more preferred embodiment, such as Figure 4 and Figure 5 As shown. It also includes a fixing plate 5 that covers the pin plate 2. The fixing plate 5 has a glue guiding hole 51. When the fixing plate 5 covers the pin plate 2, the glue guiding hole 51 and the glue overflow hole 31 are connected to form a glue overflow channel 52. The inner diameter of the glue overflow channel 52 gradually increases from the tapered guide hole 311. A glue storage tank 53 that communicates with the top of the glue overflow channel 52 is also opened on the upper surface of the fixing plate 5. The top template 6 is covered above the fixing plate 5, and the bottom template 4 is connected below the middle template 1.

[0045] In this embodiment, the inner diameter of the overflow channel 52 gradually increases, resulting in a higher flow rate of adhesive or air initially entering the overflow channel 52 during the discharging or venting process. As more adhesive or gas enters the overflow channel 52, the gradually increasing inner diameter can accommodate more adhesive or gas and slowly discharge it into the storage tank 53. The storage tank 53 is designed to facilitate the unified storage of adhesive during discharging and to allow for convenient centralized and unified cleaning when removing adhesive.

[0046] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0047] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for molding porous rubber parts, characterized in that, Includes the following steps: Pre-forming S1 provides a fixed volume storage space (K) for filling the storage space (K) with adhesive. After heating and softening the adhesive, a pre-forming hole (100) is formed in the adhesive. The cross-section of the pre-forming hole (100) has a dividing interface (101). Above the dividing interface (101), the inner diameter of the pre-forming hole (100) is smaller than the inner diameter of the forming hole (200). Below the dividing interface (101), the inner diameter of the pre-forming hole (100) is larger than the inner diameter of the forming hole (200). The volume of the pre-forming hole (100) is the same as that of the forming hole (200). In the second stage of molding S2, a pin (300) is placed in the pre-formed hole (100). The outer dimensions of the pin (300) match the forming hole (200). A molding process is used to apply pressure to the adhesive in the storage space (K) so that the adhesive adheres to the outer wall of the pin (300). Demolding and forming S3, after the rubber material cools, remove the insert (300) to form a porous rubber part.

2. The method for molding porous rubber parts as described in claim 1, characterized in that, The inner wall of the preformed hole (100) has a draft taper.

3. The method for molding porous rubber parts as described in claim 2, characterized in that, The bottom of the preformed hole (100) is an arc-shaped bottom surface.

4. The method for molding porous rubber parts as described in claim 3, characterized in that, The depth of the pre-formed hole (100) is not less than the depth of the formed hole (200).

5. The porous rubber part molding method as described in claim 2, wherein the inner wall below the interface (101) of the pre-formed hole (100) is a concave arc surface or a stepped surface.

6. The method for molding porous rubber parts as described in claim 5, characterized in that, The preforming step S1 also includes the following steps: Place a pre-formed insert S11, and place a pre-formed insert (400) in the glue material in the glue storage space (K). The volume of the part of the pre-formed insert (400) extending into the glue storage space (K) is the same as that of the part of the insert (300) extending into the glue storage space (K). The external dimensions of the pre-formed insert (400) match the pre-formed hole (100). Apply pressure to the glue material in the glue storage space (K) using a molding process to make the glue material adhere to the outer wall of the pre-formed insert (400). Pre-forming demolding S12, removing the pre-forming insert (400) to form a pre-forming hole (100).

7. A porous rubber part molding die, employing the porous rubber part molding method as described in claim 6, characterized in that, It includes a middle template (1), which has a cavity (11) for holding the adhesive material, and also includes a pin plate (2). The bottom surface of the pin plate (2) can be connected to a pre-formed pin (400) or a pin (300). After the pin plate (2) is covered on the middle template (1), the volume of the pre-formed pin (400) or pin (300) extending into the cavity (11) is the same.

8. The porous rubber part molding die as described in claim 7, characterized in that, The insert plate (2) has a through-hole (31) for overflowing glue.

9. The porous rubber part molding die as described in claim 8, characterized in that, The bottom end of the overflow hole (31) has a tapered guide hole (311).

10. The porous rubber part molding die as described in claim 8, characterized in that, It also includes a fixing plate (5) that covers the pin plate (2), and a glue guiding hole (51) is provided on the fixing plate (5). When the fixing plate (5) covers the pin plate (2), the glue guiding hole (51) and the glue overflow hole (31) are connected to form a glue overflow channel (52). The inner diameter of the glue overflow channel (52) gradually increases from the tapered guide hole (311). A glue storage tank (53) that communicates with the top of the glue overflow channel (52) is also provided on the upper surface of the fixing plate (5). A top template (6) is covered on the top of the fixing plate (5), and a bottom template (4) is connected below the middle template (1).

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