Polytetrafluoroethylene plastic multi-layer combined cold pressing die

Abstract

The utility model provides a polytetrafluoroethylene plastic multi-layer combined cold pressing die. The PTFE plastic multi-layer combined cold pressing die comprises an outer die, an upper pressing block, a lower pressing block and a die unloading sleeve, the outer die comprises an outer sleeve and an inner sleeve, the inner sleeve is of a cylindrical structure, the inner wall of the inner sleeve is an equal-diameter circular wall, the outer wall of the inner sleeve is a multi-stage circular wall with the diameter increasing or decreasing in the die pressing direction, and the outer sleeve is of a cylindrical structure. The outer wall is a conical wall with the diameter continuously increasing in the mold pressing direction, and the inner wall structure is matched with the outer wall structure of the inner sleeve and connected with the outer wall structure of the inner sleeve in a transition fit mode. The PTFE plastic multi-layer combined cold pressing die solves the problems that an existing PTFE plastic die is multiple in specification and high in die cost.

Description

Technical Field

[0001] The utility model relates to the field of cold pressing molds, in particular to a polytetrafluoroplastic multilayer combined cold pressing mold. Background Art

[0002] The industry's compression molding of PTFE plastics mostly utilizes a movable, closed mold structure. "Moving" means the mold is intermittently and periodically removed from the hydraulic press during the molding process. This mold structure is simple and inexpensive, but labor-intensive and inefficient. "Closed" means the feed cavity has the same cross-sectional dimensions and shape as the molding hole—in other words, it serves as an extension of the molding hole. This structure ensures that the pressing pressure is fully transmitted to the projected horizontal surface of the product, thus ensuring a high degree of density. The thickness of the product is not determined by the clearance when the mold is closed, but rather by the amount of material fed. PTFE plastics are typically molded into blanks at room temperature, while other fluoroplastics are press-molded above their melting point. For ease of distinction, molds used for room-temperature PTFE molding are referred to as cold-pressing molds, while molds for other fluoroplastics are referred to as hot-pressing molds. To prevent the mold sleeve from being damaged and deformed by the pressure generated by the press, the cold-pressing mold sleeve should have sufficient wall thickness to ensure a certain level of strength and rigidity. In reality, although fluororesins exert high pressure per unit area during compression molding, comprehensive data on the horizontal component of force acting on the mold sleeve wall is currently lacking. Therefore, designers often determine mold sleeve wall thickness based on experience, primarily to ensure sufficient strength and rigidity during compression.

[0003] The PTFE rod, tube, and sleeve compression molding process relies heavily on molds. Currently, the molds typically consist of an outer mold, an upper block, a lower block, and a mold removal sleeve. During compression, the outer mold, upper block, and lower block are assembled to form a mold cavity, which is then filled with the raw material. After compression, the blank is removed through the mold removal sleeve and placed in a heated oven for high-temperature sintering. After sintering, it is slowly cooled to a low temperature and the finished product is removed.

[0004] In the process of implementing the above technical solution, it was found that when using existing molds to produce PTFE blanks, a mold is required for each specification, and the wall thickness of the mold is very thick. In addition, PTFE products on the market are highly customized products with multiple specifications. In this case, the mold production will also have multiple specifications, which will result in very high mold costs. Utility Model Content

[0005] In order to solve the problem that existing PTFE plastic molds have many specifications and high mold costs, the utility model provides a PTFE plastic multi-layer combined cold pressing mold that solves the above problems.

[0006] A polytetrafluoroplastic multi-layer combined cold pressing mold includes an outer mold, an upper pressing block, a lower pressing block and a mold removal sleeve. The outer mold includes an outer sleeve and an inner sleeve. The inner sleeve is a cylindrical structure, the inner wall is a constant diameter circular wall, and the outer wall is a multi-stage circular wall with increasing or decreasing diameter along the molding direction. The outer sleeve is a cylindrical structure, and the outer wall is a conical wall with continuously increasing diameter along the molding direction. The inner wall structure is adapted to the outer wall structure of the inner sleeve, and the two are connected and transitionally matched with each other.

[0007] In a preferred embodiment of the polytetrafluoroplastic multilayer cold-pressing mold provided by the present invention, the inner sleeve comprises multiple types, each type having increasing inner and outer diameters and the same wall thickness, and each type comprising multiple configurations, each with decreasing inner dimensions. The outer sleeve comprises multiple types, each type having increasing inner and outer diameters and discontinuously increasing wall thickness.

[0008] In a preferred embodiment of the polytetrafluoroethylene plastic multilayer cold-pressing mold provided by the present invention, the inner sleeve comprises multiple types, with inner and outer diameters increasing in 10mm increments. Each type comprises 10 configurations, with inner diameters decreasing in 1mm increments. The wall thickness of the outer sleeve increases in 15mm increments.

[0009] In a preferred embodiment of the polytetrafluoroplastic multi-layer combined cold pressing mold provided by the present invention, the inner wall of the inner sleeve is provided with a circle of chamfers at the head end in the molding direction.

[0010] In a preferred embodiment of the polytetrafluoroplastic multi-layer combined cold pressing mold provided by the present invention, the outer wall of the outer sleeve is provided with a circle of grooves at the head end in the molding direction, forming a circular wall of equal diameter at the position of the groove, and a limiting mechanism is provided that penetrates into the inner sleeve.

[0011] The outer wall of the inner sleeve is provided with a circle of grooves along the circumferential direction near the head end in the molding direction; the outer sleeve is provided with a through hole at the groove position, the through hole of the outer sleeve is aligned with the groove of the inner sleeve, and a screw is provided in the through hole to penetrate into the groove and be threadedly connected to the groove.

[0012] Compared with the prior art, the polytetrafluoroethylene plastic multilayer cold pressing mold provided by the present invention has the following beneficial effects:

[0013] 1. The utility model adopts a structure in which an outer sleeve and an inner sleeve cooperate to cover multiple sizes. The same outer sleeve can be adapted to multiple inner sleeves of different sizes. To change the size, only the inner sleeve needs to be replaced.

[0014] 2. The same set of molds can be adapted to a variety of products, reducing mold costs.

[0015] 3. The outer shell of the utility model is designed to be small at the top and large at the bottom, which greatly improves the strength and rigidity of the mold. With the same weight, the compressive strength it can withstand is higher.

[0016] 4. This utility model utilizes a stepped structure to mate the outer and inner sleeves, improving fit precision and better distinguishing the upper and lower ends. This effectively prevents the inner sleeve from falling out during mold handling and assembly / disassembly, thus avoiding the risk of injury. The steps also serve as a positioning foundation during assembly, preventing excessive height differences between the outer and inner sleeves.

[0017] 5. Bolts can be used to lock the inner and outer molds, effectively preventing them from loosening and improving their firmness. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 1 is a cross-sectional view of the polytetrafluoroplastic multilayer cold-pressing mold in Example 1;

[0019] Figure 2 It is a cross-sectional view of the polytetrafluoroplastic multilayer cold-pressing mold in Example 3.

[0020] Numbers in the figure: upper pressing block 2, lower pressing block 3, die removal sleeve 4, retaining bolt 5;

[0021] Outer sleeve 11, inner sleeve 12, and card slot 13. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Example 1:

[0023] See also Figure 1 , is a cross-sectional view of the polytetrafluoroplastic multilayer combined cold pressing mold in this embodiment.

[0024] The polytetrafluoroplastic multilayer cold pressing mold comprises an outer mold, an upper pressing block 2 , a lower pressing block 3 , a mold removal sleeve 4 and a retaining bolt 5 , wherein the outer mold comprises an outer sleeve 11 and an inner sleeve 12 .

[0025] The inner sleeve 12 is cylindrical in shape, with a smooth inner wall of constant diameter of 50 mm. The outer wall has a thicker upper section and a thinner lower section, i.e., a secondary circular wall with decreasing diameters from top to bottom, with diameters of 60 mm and 58 mm respectively. The wall thickness is roughly 10 mm.

[0026] A circle of slots 13 are provided on the outer wall of the inner sleeve 12 near the top.

[0027] The outer sleeve 11 is cylindrical, with a coarse upper section and a finer lower section, i.e., two layers of circular wall with decreasing diameters from top to bottom, 60 mm and 58 mm, respectively. The outer wall is a conical structure with a continuously increasing diameter, from 70 mm to 75 mm. The wall thickness is roughly 15 mm.

[0028] A circle of grooves is provided on the outer wall of the outer sleeve 11 near the top, and a through hole is provided at the position of the groove, penetrating the outer sleeve 11 and communicating with the card slot 13 .

[0029] During installation, the inner sleeve 12 is inserted from top to bottom into the outer sleeve 11, and the two are connected and transitionally matched. The outer sleeve 11 is preheated to reduce the difficulty of assembly. Then, the retaining bolt 5 is screwed into the through hole of the outer sleeve 11, engaging with the retaining groove 13 to achieve the limit.

[0030] The above is one category of outer cover 11 and inner cover 12.

[0031] The inner sleeve 12 under this category includes 10 configurations: the outer dimensions of the 10 configurations are consistent, and they are all arranged in the outer sleeve 11 and connected and transitionally matched with each other; the inner dimensions decrease in intervals of 1 mm, that is, the wall thickness of the inner sleeve 12 increases inward in intervals of 1 mm.

[0032] Then the inner diameter of the inner sleeve 12 is between 50mm and 40mm, and the overall thickness of the inner sleeve 12 and the outer sleeve 11 is between 25mm and 35mm, which is greater than the wall thickness required for processing products between 50mm and 40mm, and is suitable for producing products with a diameter between 50mm and 40mm.

[0033] Based on the existing experience and recommendations for circular cavity wall thickness, the minimum thickness of the inner sleeve 12 and outer sleeve 11 is 25mm, and the maximum thickness can be 60mm. Similarly, another mold with the same wall thickness but an inner diameter increased by 10mm can be designed.

[0034] That is, another type of outer sleeve 11 and inner sleeve 12: the inner and outer diameters of the inner sleeve 12 increase by 10 mm, while the wall thickness remains unchanged. The inner and outer diameters of the outer sleeve 11 increase by 10 mm, while the wall thickness remains unchanged.

[0035] The inner diameters of the 10 configurations of the inner sleeve 12 under this category are between 60 mm and 50 mm, and are suitable for producing products with diameters between 60 mm and 50 mm.

[0036] When in use, the inner sleeve 12 and the outer sleeve 11 are assembled into an outer mold according to the required product size. The outer mold, the upper pressing block 2 and the lower pressing block 3 are assembled to form a mold cavity, the mold cavity is filled with raw materials and pressed into a blank, and finally taken out through the demolding sleeve 4.

[0037] When it is necessary to produce products of other sizes, the inner sleeve 12 is ejected using a press, and then an inner sleeve 12 of appropriate specifications is selected and assembled into an outer mold. Example 2:

[0038] The structure is the same as that of Example 1.

[0039] Another type of outer sleeve 11 and inner sleeve 12: the inner and outer diameters of the inner sleeve 12 increase by 10 mm, while the wall thickness remains unchanged. The inner and outer diameters of the outer sleeve 11 increase by 10 mm, while the wall thickness increases by 15 mm.

[0040] Specifically, the inner diameter of the inner sleeve 12 is 70 mm, the outer diameter is 80 mm and 78 mm, and the wall thickness is roughly 10 mm. The inner diameter of the outer sleeve 11 is 80 mm and 78 mm, the outer diameter ranges from 105 mm to 110 mm, and the wall thickness is roughly 30 mm.

[0041] The inner diameters of the 10 configurations of the inner sleeve 12 in this category range from 70mm to 60mm, and the thickness of the inner sleeve 12 and the outer sleeve 11 as a whole ranges from 40mm to 50mm. This is suitable for producing products with diameters between 70mm and 60mm.

[0042] Based on the existing recommended values ​​of circular cavity wall thickness, the minimum thickness of the inner sleeve 12 and the outer sleeve 11 is 40 mm, and the maximum thickness that can be supported is 100 mm.

[0043] Similarly, we can design three more sets of molds with the same wall thickness but with inner diameters increased by 10mm, 20mm, and 30mm respectively. We will not go into details here. Example 3:

[0044] See also Figure 2 , is a cross-sectional view of the polytetrafluoroplastic multilayer combined cold pressing mold in this embodiment.

[0045] The polytetrafluoroplastic multilayer cold pressing mold comprises an outer mold, an upper pressing block 2 , a lower pressing block 3 , a mold removal sleeve 4 and a retaining bolt 5 , wherein the outer mold comprises an outer sleeve 11 and an inner sleeve 12 .

[0046] The inner sleeve 12 is cylindrical in shape, with a smooth inner wall of constant diameter of 50 mm. The outer wall has a thinner upper section and a thicker lower section, i.e., a secondary circular wall with increasing diameters from top to bottom, with diameters of 60 mm and 58 mm respectively. The wall thickness is roughly 10 mm.

[0047] A circle of slots 13 are provided on the outer wall of the inner sleeve 12 near the top.

[0048] The outer sleeve 11 is cylindrical, with a thinner upper section and thicker lower section, i.e., two layers of circular wall with increasing diameters from top to bottom, 60mm and 58mm respectively. The outer wall is a conical structure with continuously increasing diameters, from 70mm to 75mm. The wall thickness is roughly 15mm.

[0049] A circle of grooves is provided on the outer wall of the outer sleeve 11 near the top, and a through hole is provided at the position of the groove, penetrating the outer sleeve 11 and communicating with the card slot 13 .

[0050] During installation, the inner sleeve 12 is inserted from bottom to top into the outer sleeve 11, and the two are connected and transitionally matched. The outer sleeve 11 is preheated to reduce the difficulty of assembly. Then, the retaining bolt 5 is screwed into the through hole of the outer sleeve 11, engaging with the retaining groove 13 to achieve the fixed position.

[0051] Other contents are consistent with those in Example 1.

[0052] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A polytetrafluoroplastic multilayer cold pressing mold, comprising an outer mold, an upper pressing block, a lower pressing block and a mold removal sleeve, characterized in that: The outer mold includes an outer sleeve and an inner sleeve. The inner sleeve is a cylindrical structure, the inner wall is a constant diameter circular wall, and the outer wall is a multi-level circular wall with increasing or decreasing diameter along the molding direction. The outer sleeve is a cylindrical structure, and the outer wall is a conical wall with continuously increasing diameter along the molding direction. The inner wall structure is adapted to the outer wall structure of the inner sleeve, and the two are connected and transitionally matched with each other.

2. The polytetrafluoroplastic multi-layer cold pressing mold according to claim 1, characterized in that: The inner sleeve includes multiple categories, and the inner and outer diameters of different categories increase gradually, and the wall thickness is the same. Each category includes multiple configurations, and the inner size of each configuration decreases gradually.

3. The polytetrafluoroplastic multi-layer cold pressing mold according to claim 2, characterized in that: The inner and outer diameters of the different categories of the inner sleeve increase at intervals of 10 mm, each category includes 10 configurations, and the inner diameters of the 10 configurations decrease at intervals of 1 mm.

4. The polytetrafluoroplastic multi-layer cold pressing mold according to claim 1, characterized in that: The outer sleeve includes multiple categories, and the inner and outer diameters of different categories increase gradually, and the wall thickness increases discontinuously.

5. The polytetrafluoroplastic multi-layer cold pressing mold according to claim 4, characterized in that: The wall thickness of the different types of jackets increases in units of 15 mm.

6. The polytetrafluoroplastic multi-layer cold pressing mold according to any one of claims 1 to 5, characterized in that: The inner wall of the inner sleeve is provided with a chamfer at the head end in the molding direction.

7. The polytetrafluoroplastic multi-layer cold pressing mold according to any one of claims 1 to 5, characterized in that: The outer wall of the outer sleeve is provided with a circle of grooves at the head end in the molding direction, forming a circular wall of equal diameter at the position of the groove, and is provided with a limiting mechanism that penetrates into the inner sleeve.

8. The polytetrafluoroplastic multi-layer cold pressing mold according to claim 7, characterized in that: The outer wall of the inner sleeve is provided with a circle of grooves along the circumferential direction near the head end in the molding direction; the outer sleeve is provided with a through hole at the groove position, the through hole of the outer sleeve is aligned with the groove of the inner sleeve, and a screw is provided in the through hole to penetrate into the groove and be threadedly connected to the groove.

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