Porous rubber part forming method and mold

Abstract

A porous rubber part forming method comprises the steps that S1, a rubber storage space with the fixed volume is provided, the rubber storage space is filled with a rubber material, and after the rubber material is heated to be softened, preformed holes are formed in the rubber material; s2, an insert pin is placed in the pre-forming hole, the appearance size of the insert pin is matched with that of the forming hole, pressure is applied to the rubber material in the rubber storage space through the mold pressing technology, and the rubber material is made to be attached to the outer wall of the insert pin; and S3, after the rubber material is vulcanized, the insert pin is pulled out, and the porous rubber part is formed. According to the forming method and the mold, a two-section forming method is adopted, the rough insert pin is firstly used for preforming, then the forming insert pin is used for vulcanization forming, the rough insert pin and the forming insert pin are designed in an isovolumetric mode, and the forming insert pin can be prevented from being bent or broken due to extrusion of rubber materials.

Description

Technical Field

[0001] The invention relates to the field of rubber component vulcanization molding technology and molding molds, and in particular to a porous rubber component molding method and a mold. Background Art

[0002] In some finished rubber parts, there are multiple holes in the rubber that are similar to an inverted gourd or inverted cone. Figure 1 As shown, there are multiple forming holes 200 distributed in the rubber part. These forming holes 200 are often densely distributed, with small spacing between each other and large aspect ratio of the holes. The inner diameter of the cross section of the forming hole 200 gradually decreases from the top to the bottom, the inner diameter of the top is larger, and the side wall is in a concave arc shape. Generally speaking, this type of porous rubber part is formed by molding, and inserting a pin into the molding mold is used. After molding, these holes can be formed by removing the insert pin. However, the aforementioned forming holes 200 have a large aspect ratio, a very small inner diameter at the bottom, and a single rubber part is densely distributed. If the insert pin matching the forming hole 200 is directly used for one-time molding, the insert pin will be squeezed by the rubber after being inserted into the mold, and the insert pin with a large aspect ratio often breaks, resulting in molding failure. Therefore, it is necessary to propose an improved molding method and mold for processing and production of this type of porous rubber part with a large aspect ratio. Summary of the invention

[0003] In view of the shortcomings of the prior art, the present invention provides a method for forming a porous rubber part, comprising the following steps: Preforming S1, providing a glue storage space with a fixed volume, filling the glue storage space with glue, heating the glue to soften it, and forming a preformed hole in the glue, wherein the cross section of the preformed hole has an interface, above which the inner diameter of the preformed hole is smaller than that of the formed hole, and below which the inner diameter of the preformed hole is larger than that of the formed hole, and the volume of the preformed hole is consistent with that of the formed hole; Second stage forming S2, placing an insert pin in the preformed hole, the outer dimensions of the insert pin matching the formed hole, applying pressure to the rubber in the rubber storage space by a molding process, so that the rubber fits the outer wall of the insert pin; Demolding S3, after the rubber material is vulcanized, the insert pins are removed to form a porous rubber part.

[0004] Furthermore, the inner wall of the preformed hole has a draft taper.

[0005] Furthermore, the bottom of the preformed hole is an arc-shaped bottom surface.

[0006] Furthermore, the depth of the preformed hole is not less than the depth of the formed hole.

[0007] Furthermore, the inner wall below the interface of the preformed hole is a concave arc surface or a stepped surface.

[0008] Furthermore, the preforming step S1 further includes the following steps: Placing a preformed insert pin S11, placing a preformed insert pin in the rubber material in the rubber storage space, the volume of the portion of the preformed insert pin extending into the rubber storage space is consistent with the volume of the portion of the insert pin extending into the rubber storage space, the outer dimensions of the preformed insert pin match the preformed hole, and a molding process is used to apply pressure to the rubber material in the rubber storage space so that the rubber material fits the outer wall of the preformed insert pin; The preforming demolding S12 removes the preforming pin to form a preforming hole.

[0009] A porous rubber part forming mold is also proposed, including a middle template, the middle template has a cavity for accommodating rubber material, and also includes a needle inserting plate, the bottom surface of the needle inserting plate can be connected to a preformed inserting pin or an inserting pin, when the needle inserting plate is covered on the top of the middle template, the volume of the part of the preformed inserting pin or the inserting pin extending into the cavity is consistent.

[0010] Furthermore, a through glue overflow hole is provided on the needle inserting plate.

[0011] Furthermore, the bottom end of the glue overflow hole is provided with a tapered guide hole.

[0012] Furthermore, it also includes a fixed plate covering the needle inserting plate, and a glue guide hole is opened on the fixed plate. When the fixed plate covers the needle inserting plate, the glue guide hole and the glue overflow hole are connected to form a glue overflow channel, and the inner diameter of the glue overflow channel gradually increases from above the conical guide hole; a glue storage tank connected to the top of the glue overflow channel is also opened on the upper surface of the fixed plate; a top template is covered on the top of the fixed plate, and the bottom template is connected to the bottom of the middle template.

[0013] Compared with the prior art, the technical solution of the present application has the following beneficial effects: the molding method and mold proposed in the present invention adopt a two-stage molding method, first using a coarse inlay pin for pre-molding, and then using a molding inlay pin for vulcanization molding. The coarse inlay pin and the molding inlay pin are designed with equal volumes, which can avoid bending or breaking of the molding inlay pin due to extrusion of the rubber material. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 : Cross-sectional view of the porous rubber part; Figure 2 : Schematic diagram of the steps for forming porous rubber parts; Figure 3 : Schematic diagram of the forming steps of the preformed hole; Figure 4 : Schematic diagram of the overall structure of the molding die; Figure 5 : Schematic diagram of the split structure of the molding die; Figure 6 : A cross-sectional view of the needle plate connected to the preformed needle; Figure 7 : A cross-sectional view of the needle plate connected to the needle; Figure 8 : Schematic diagram of the local enlarged structure of the glue overflow hole. DETAILED DESCRIPTION

[0015] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0016] A method for forming a porous rubber part comprises the following steps: Preforming S1, providing a glue storage space K with a fixed volume, filling the glue storage space K with glue, heating the glue to soften it, and then forming a preformed hole 100 in the glue, wherein the cross section of the preformed hole 100 has a boundary surface 101, above which the inner diameter of the preformed hole 100 is smaller than the inner diameter of the forming hole 200, and below which the inner diameter of the preformed hole 100 is larger than the inner diameter of the forming hole 200, and the volume of the preformed hole 100 is consistent with that of the forming hole 200; Second stage forming S2, placing a pin 300 in the preformed hole 100, the outer dimensions of the pin 300 match the forming hole 200, and applying pressure to the rubber in the rubber storage space K by a molding process, so that the rubber adheres to the outer wall of the pin 300; Demolding S3, after the rubber material is cooled, the insert pins 300 are removed to form a porous rubber part.

[0017] The above constitutes the basic steps of the molding method proposed in the present invention, among which the pre-molding step S1 is more critical. Figure 1 and Figure 2 As shown, the volumes of the preformed hole 100 and the formed hole 200 are consistent. Since the preformed hole 100 is divided into two sections by the interface 101, the upper section has a smaller inner diameter than the formed hole 200, and the lower section has a larger inner diameter than the formed hole 200. In short, the aspect ratio of the preformed hole 100 relative to the formed hole 200 is smaller, and the inner diameter changes more evenly. After the preformed hole 100 is formed, the pressure of the rubber on the insert pin 300 will be greatly reduced, thereby preventing the insert pin 300 from being squeezed and broken. When the insert pin 300 is gradually placed into the preformed hole 100, before it contacts the interface 101, the front half of the insert pin 300 is free to enter the preformed hole 100 and will not be squeezed by the rubber. The insert pin 300 continues to be placed downward, and the side walls of the insert pin 300 are squeezed by the rubber at the interface 101, from Figure 2The squeezed area can be seen at the solid filling. Since the volume of the glue storage space K is fixed, and the outer dimensions of the insert pin 300 and the molding hole 200 have the same volume as the pre-molded hole 100, during the extrusion with the rubber, the rubber will be squeezed and flow to the side wall of the insert pin 300. That is, after the insert pin 300 enters the pre-molded hole 100, the empty area below the interface 101 will be gradually filled with the rubber that flows after the extrusion. Finally, when the insert pin 300 is pulled out, a molding hole 200 that meets the requirements is formed.

[0018] The forming of the preform S1 can be performed in a similar manner to the forming of the forming hole 100. Figure 3 : Place the preformed insert pin S11, place the preformed insert pin 400 in the rubber material of the rubber storage space K, the volume of the portion of the preformed insert pin 400 extending into the rubber storage space K is consistent with the volume of the portion of the insert pin 300 extending into the rubber storage space K, the outer dimensions of the preformed insert pin 400 match the preformed hole 100, and a molding process is used to apply pressure to the rubber material in the rubber storage space K so that the rubber material fits the outer wall of the preformed insert pin 400; preform demolding S12, remove the preformed insert pin 400 to form the preformed hole 100. Since the aspect ratio of the preformed hole 100 is smaller than that of the formed hole 100, the overall outer diameter of the preformed insert pin 400 is larger than that of the insert pin 300, except that the outer diameter of the upper half of the preformed insert pin 400 corresponding to the interface 101 is smaller than that of the insert pin 300. Figure 3 It can be seen that the preformed insert pin 400 is a thicker insert pin with a nearly uniform outer diameter from top to bottom compared to the insert pin 300. Therefore, when it is inserted into the rubber pile, its compression resistance is better than that of the insert pin 400, and it will not break due to the squeezing of the rubber.

[0019] It should be noted that, in general, in addition to using similar steps to form the pre-formed hole 100, other common processes such as injection molding can also be used. The focus of this embodiment is that the volume of the pre-formed hole 100 after forming is consistent with the forming hole 200 and has the aforementioned interface 101.

[0020] In a more preferred embodiment, in order to facilitate the demoulding and removal of the preformed insert 400, the inner wall of the preformed hole 100 has a draft taper.

[0021] In a more preferred embodiment, the bottom of the preformed hole 100 is an arc-shaped bottom surface 101. The arc-shaped bottom surface 101 facilitates the separation between the bottom of the preformed hole 100 and the preformed insert pin 400, and also facilitates the rubber material at the bottom surface to flow and fit the side wall of the insert pin 300 more smoothly after being squeezed.

[0022] In a more preferred embodiment, the depth of the preformed hole 100 is not less than the depth of the formed hole 200. Generally speaking, it is more preferred that the depth of the preformed hole 100 is greater than the depth of the formed hole 200, because after the insert pin 300 is inserted into the preformed hole 100, its small end will not be squeezed and contacted with the rubber at the bottom of the preformed hole 100. It should be noted that this is not necessary. If the depth of the preformed hole 100 is less than the depth of the formed hole 200, even if the insert pin 300 is squeezed and contacted with the rubber at the bottom of the preformed hole 100, the contact pressure and the volume of the rubber are much smaller than when there is no preformed hole 100, which still has a positive effect on avoiding the breakage of the insert pin 300. In this embodiment, the depth of the preformed hole 100 is equal to the depth of the formed hole 200. That is, the insert pin 300 and the bottom of the preformed hole 100 will not be squeezed, but will be slightly in contact.

[0023] In a more preferred embodiment, the inner wall below the interface 101 of the preformed hole 100 is a concave arc surface 102 or a stepped surface 103. There is an empty area between this part of the inner wall and the insert pin 300 at the initial stage of the rubber extrusion. After being extruded, it will gradually flow and fit the side wall of the insert pin 300. The inner wall below the interface 101 is a concave arc surface 102 or a stepped surface 103, which can reduce the distance between this part and the side wall of the insert pin 300, and the smoother transition makes the flow and fit of the rubber extrusion of this part smoother.

[0024] In another embodiment, a porous rubber part forming mold is proposed for the above implementation method, which can be seen in Figure 6 and Figure 7 , including a middle template 1, which has a cavity 11 for accommodating the rubber material, and also includes a needle inserting plate 2, the bottom surface of which can be connected to the preformed needle 400 or the needle 300. When the needle inserting plate 2 is covered on the middle template 1, the volume of the part of the preformed needle 400 or the needle 300 extending into the cavity 11 is consistent.

[0025] After the needle inserting plate 2 is covered on the middle template 1, the cavity 11 is completely closed, and the rubber material will flow evenly after being squeezed to fit the preformed needle 400 or the needle 300 to form a preformed hole 100 or a formed hole 200. It can be understood that when it is necessary to form a preformed hole 100, the bottom surface of the needle inserting plate 2 can be connected to the preformed needle 400, and the preformed needle 400 is removed from the mold with the needle inserting plate 2 to form a preformed hole 100; subsequently, the formed needle 400 is connected to the bottom surface of the needle inserting plate 2, and the same implementation steps are followed to form a formed hole 200 by secondary molding. The specific implementation method of the needle inserting plate 2 connecting the preformed needle 400 or the needle 300 can be that the preformed needle 400 and the needle 300 are removable, and the preformed needle 400 or the needle 300 can be connected to the bottom surface of the needle inserting plate 2 as needed. Alternatively, the needle inserting plate 2 can be divided into two pieces, one piece connected to the preformed needle inserting 400 and the other piece connected to the needle inserting 300, and one piece can be selected to cover the middle template 1 as needed. Obviously, when the number of holes is large, it is more reasonable to replace the needle inserting plate 2 as a whole, avoiding the cumbersome removal and replacement of the preformed needle inserting 400 or the needle inserting 300 separately.

[0026] In a more preferred embodiment, a through overflow hole 31 is provided on the needle inserting plate 2. The overflow hole 31 can allow the squeezed excess glue to be discharged from the overflow hole 31 after the needle inserting plate 2 is covered on the middle template 1.

[0027] In a more preferred embodiment, the bottom end of the overflow hole 31 is provided with a conical guide hole 311. The conical guide hole 311 is as shown in FIG. Figure 8 As shown, the cross section is an inverted frustum, so that the glue that needs to be discharged by squeezing near the bottom end of the glue overflow hole 31 can be guided to flow into the conical guide hole 311 and finally discharged through the glue overflow hole 31.

[0028] In a more preferred embodiment, Figure 4 and Figure 5 It also includes a fixing plate 5 covering the needle inserting plate 2, and a glue guide hole 51 is provided on the fixing plate 5. When the fixing plate 5 covers the needle inserting plate 2, the glue guide hole 51 is connected with the glue overflow hole 31 to form a glue overflow channel 52, and the inner diameter of the glue overflow channel 52 gradually increases from above the conical guide hole 311; a glue storage tank 53 connected to 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 fixing plate 5, and a bottom template 4 is connected to the bottom of the middle template 1.

[0029] In this embodiment, the inner diameter of the overflow glue channel 52 is gradually increased, so that during the process of glue discharge or exhaust, the glue or air initially entering the overflow glue channel 52 will have a higher flow rate. As the glue or gas enters the overflow glue channel 52, the gradually increased inner diameter can accommodate more glue or gas and slowly discharge it into the glue storage tank 53. The design of the glue storage tank 53 is to facilitate the glue discharge, so that the glue can be uniformly stored in the glue storage tank 53, and it is convenient to centrally clean up when removing the glue.

[0030] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0031] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for forming a porous rubber part, characterized in that: The steps include: Preforming S1, providing a glue storage space (K) with a fixed volume, filling the glue storage space (K) with glue, heating the glue to soften it, and then forming a preformed hole (100) in the glue, wherein the cross section of the preformed hole (100) has an interface (101), the inner diameter of the preformed hole (100) above the interface (101) is smaller than the inner diameter of the forming hole (200), and the inner diameter of the preformed hole (100) below the interface (101) is larger than the inner diameter of the forming hole (200), and the volume of the preformed hole (100) is consistent with that of the forming hole (200); Second stage forming S2, placing an insert pin (300) in the preformed hole (100), wherein the outer dimensions of the insert pin (300) match those of the formed hole (200), and applying pressure to the rubber in the rubber storage space (K) by a molding process, so that the rubber adheres to the outer wall of the insert pin (300); Demolding S3, after the rubber material is cooled, the insert pin (300) is removed to form a porous rubber part.

2. The method for forming a porous rubber part according to claim 1, characterized in that: The inner wall of the preformed hole (100) has a draft taper.

3. The method for forming a porous rubber part according to claim 2, characterized in that: The bottom of the preformed hole (100) is an arc-shaped bottom surface (101).

4. The method for forming a porous rubber part according to claim 3, characterized in that: The depth of the preformed hole (100) is not less than the depth of the formed hole (200).

5. The method for forming a porous rubber part according to claim 2, wherein the inner wall below the interface (101) of the preformed hole (100) is a concave arc surface (102) or a stepped surface (103).

6. The method for forming a porous rubber part according to claim 5, characterized in that: The preforming step S1 also includes the following steps: Placing a preformed insert pin S11, placing a preformed insert pin (400) in the glue of the glue storage space (K), the volume of the portion of the preformed insert pin (400) extending into the glue storage space (K) being consistent with the volume of the portion of the insert pin (300) extending into the glue storage space (K), the outer dimensions of the preformed insert pin (400) matching the preformed hole (100), applying pressure to the glue in the glue storage space (K) by a molding process, so that the glue adheres to the outer wall of the preformed insert pin (400); The pre-forming mold is demoulded S12, and the pre-forming pin (400) is removed to form a pre-forming hole (100).

7. A porous rubber part forming mold, characterized in that: The invention comprises a middle template (1), the middle template (1) is provided with a cavity (11) for accommodating a rubber material, and also comprises a needle inserting plate (2), the bottom surface of which can be connected with a preformed needle (400) or a needle inserting plate (300), and when the needle inserting plate (2) is covered on the middle template (1), the volume of the part of the preformed needle (400) or the needle inserting plate (300) extending into the cavity (11) is the same.

8. The porous rubber molding die according to claim 7, characterized in that: The needle inserting plate (2) is provided with a through glue overflow hole (31).

9. The porous rubber molding die according to claim 8, characterized in that: The bottom end of the glue overflow hole (31) is provided with a conical guide hole (311).

10. The porous rubber molding die according to claim 8, characterized in that: The invention also comprises a fixed plate (5) covering the needle inserting plate (2), a glue guide hole (51) being provided on the fixed plate (5), and when the fixed plate (5) is covered on the needle inserting plate (2), the glue guide hole (51) and the glue overflow hole (31) are connected to form a glue overflow channel (52), and the inner diameter of the glue overflow channel (52) gradually increases from above the conical guide hole (311); a glue storage groove (53) connected to the top of the glue overflow channel (52) is also provided on the upper surface of the fixed plate (5); a top template (6) is covered on the top of the fixed plate (5), and the bottom of the middle template (1) is connected to the bottom template (4).

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