COMPRESSION MOLDING DIE FOR I-SHAPED PART

Abstract

Provided is a compression molding die. The die can be used for compression molding an I-shaped part without the need for machining. The molding die comprises: an outer mold with an inner diameter of d; an upper pressing disc, a lower pressing disc and a huff mold with the same outer diameter of d and the same inner diameter of f; an upper mold; a lower mold; and a core mold with a diameter of h. The upper pressing disc, the huff mold and the lower pressing disc, which are movable vertically, are arranged in the outer mold in a vertically spaced manner; the vertically movable upper mold extends into the upper pressing disc, and the vertically movable lower mold extends into the lower pressing disc; the outer mold, the upper mold, the upper pressing disc, the huff mold, the lower pressing disc and the lower mold define a cavity.

Claims

1. A compression molding die for I-shaped part, the I-shaped part comprises a middle shaft, an upper wing plate and lower wing plate; the middle shaft has an outer diameter f and a height e; each of the upper wing plate and the lower wing plate has a diameter d and a height g; and, d is greater than f wherein: the molding die comprises: an outer mold with an inner diameter d, an upper pressing disc, a lower pressing disc, a huff mold, an upper mold and a lower mold, wherein each of the upper pressing disc, the lower pressing disc and the huff mold has an outer diameter d and an inner diameter f; the upper pressing disc, the huff mold and the lower pressing disc are vertically arranged in the outer mold at an interval; the upper mold extends into the upper pressing disc; the lower mold extends into the lower pressing disc; and a mold cavity is surrounded by the outer mold, the upper mold, the upper pressing disc, the huff mold, the lower pressing disc and the lower mold.

2. The compression molding die for I-shaped part, as recited in claim 1, wherein: the I-shaped part has a core hole which runs through the middle shaft, the upper wing plate and the lower wing plate and has a diameter h; and the molding die further comprises a core mold with a diameter h, and upper and lower ends of the core mold respectively extend into holes formed on the upper mold and the lower mold.

3. The compression molding die for I-shaped part, as recited in claim 1, wherein: if a compression ratio for compression molding of raw materials is x, and x is greater than 1, the distance between the lower surface of the upper mold and the lower surface of the upper pressing disc is e(x−1)/2, the distance between the upper surface of the lower mold and the upper surface of the lower pressing disc is e(x−1)/2; the distance between the lower surface of the upper pressing disc and the upper surface of the huff mold is g(x−1), the distance between the upper surface of the lower pressing disc and the lower surface of the huff mold is g(x−1).

4. The compression molding die for I-shaped part, as recited in claim 3, wherein: the periphery of the lower end of the upper mold is step-shaped, an axle journal with a smaller diameter at the lower end of the upper mold extends in the upper pressing disc; the periphery of the upper end of the lower mold is step-shaped, and an axle journal with a small diameter at the upper end of the lower mold extends in the lower pressing disc; the distance between the step face of the upper mold and the upper surface of the upper pressing disc is e(x−1)/2, the distance between the step face of the lower mold and the lower surface of the lower pressing disc is e(x−1)/2.

5. The compression molding die for I-shaped part, as recited in claim 4, wherein: a plurality of support rings which are nested in turn are provided; an annular slot is formed at an upper end of the inner circumference of each of the support rings; the support ring with a smaller diameter is nested in the annular slot of the support ring with a greater diameter; the lower pressing disc is located in the annular slot of the support ring with the smallest diameter; an axle journal with a greater diameter at the lower end of the lower mold penetrates through the support ring with the smallest diameter, and the support ring with the greatest diameter is arranged on a mold rack.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0032] FIG. 1 is a schematic diagram of molding die used for material filling at a first time;

[0033] FIG. 2 is a schematic diagram of some of molding die used for material filling at a second time;

[0034] FIG. 3 is a schematic diagram of some of molding die used for material filling at a third time;

[0035] FIG. 4 is a schematic diagram of molding die prior to primary compression;

[0036] FIG. 5 is a schematic diagram of molding die prior to secondary compression;

[0037] FIG. 6 is a schematic diagram of molding die after compression (during pressure maintaining);

[0038] FIG. 7 is a schematic diagram of molding die during demolding;

[0039] FIG. 8 is a schematic diagram of an I-shaped part formed by compression.

[0040] Reference of numerals: 1: I-shaped part; 10: raw material: 11: middle shaft; 12: upper wing plate; 13: lower wing plate; 2: outer mold; 3: upper pressing disc; 4: lower pressing disc; 5: huff mold; 6: upper mold; 61: upper mold axle journal; 7: lower mold; 71: lower mold axle journal; 8: core mold; 9: mold cavity; 20: press; 21: mold rack; 22: support ring; 23: ejector block; 24: cushion block; 25: workbench; 26: upper pressing rod; 27: lower ejecting rod.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0041] Referring to FIG. 8, an I-shaped part 1 which needs to be molded by compression of raw materials such as polytetrafluoroethylene powder comprises a middle shaft 11, an upper wing plate 12 and a lower wing plate 13; and the I-shaped part has a vertically through core hole 14 with a diameter h. The middle shaft has an outer diameter f and a height e; and each of the upper wing plate and the lower wing plate has a diameter d and a height g; and, d is greater than f.

[0042] To compress the I-shaped part, referring to FIGS. 4, 6, and 8, molding die used comprises: an outer mold 2 with an inner diameter d, an upper pressing disc 3, a lower pressing disc 4, a huff mold 5 (composed of two semi-ring molds), an upper mold 6, a lower mold 7 and a core mold 8 with a diameter h, wherein each of the upper pressing disc, the lower pressing disc and the huff mold has an outer diameter d and an inner diameter f.

[0043] A through-hole with a diameter h penetrates through the center of each of the upper mold 6 and the lower mold 7, and upper and lower ends of the core hold respectively extend into the through-holes of the upper mold and the lower mold. The periphery of the lower end of the upper mold is step-shaped, and the upper pressing disc 3 is nested on an upper mold axle journal 61 with a smaller diameter at the lower end of the upper mold. The periphery of the upper end of the lower mold 7 is step-shaped, and the lower pressing disc is nested on a lower shaft axle journal 71 with a small diameter at the upper end of the lower mold. The upper shaft axle journal 61 and the lower mold axle journal 71 respectively have an outer diameter f.

[0044] The upper pressing disc, the huff mold and the lower pressing disc are vertically arranged in the outer mold at an interval, and a mold cavity 9 is surrounded by the outer mold, the upper mold, the upper pressing disc, the huff mold, the lower pressing disc, the lower mold, and the core mold.

[0045] To place the molding die on a press 20, a mold rack 21 is arranged on a workbench 25 of the press, and the mold rack is provided with a plurality of support rings 22. An upper pressing rod 26 which is connected to the upper mold is arranged above the upper mold 6. A cushion block 24 is arranged between an ejector block 23 of the workbench and each of the core mold 8 and the lower pressing disc 4, and a lower ejecting rod 27 for ejecting the ejector bock 23 is located below the ejector block 23.

[0046] The plurality of support rings 22 are nested in turn, which means that an annular slot is formed at an upper end of the inner circumference of each of the support rings, and the support ring with a smaller diameter is located in the annular slot of the support ring with a greater diameter. The lower pressing disc 4 is located in the annular slot of the support ring with the smallest diameter; an axle journal with a greater diameter at the lower end of the lower mold penetrates through the support ring with the smallest diameter, and the support ring with the greatest diameter is arranged on the mold rack.

[0047] A compression molding method for I-shaped part molded by compression of raw materials such as the polytetrafluoroethylene powder at a compression ratio x includes the following steps:

[0048] 1), Material filling (raw materials for compressing the I-shaped part are filled in the mold cavity). The specific process is as follows.

[0049] Material filling for the first time: Refer to FIG. 1. The mold rack is fixed on the workbench; the plurality of support rings are nested in turn; the support ring with the greatest diameter is fixed on the mold rack; the lower pressing disc is placed in the annular slot of the support ring with the smallest diameter; and the lower surface of the outer mold located on the outer periphery of the lower pressing disc contacts the upper surface of the support ring with the smallest diameter. The lower mold axle journal with a smaller diameter of the lower mold extends into the lower pressing disc, and the outer diameter of the axle journal with a greater diameter at the lower end of the lower mold is smaller than the inner diameter of the support ring with the smallest diameter. The distance t1 from the step face of the lower mold to the lower surface of the lower pressing disc is equal to e(x−1)/2. The distance u1 from the upper surface of the lower mold to the upper surface of the lower pressing disc is equal to t1. The core mold penetrates through the lower mold; the cold mold and the lower mold both are located on the cushion block; and a lower end of the cushion block contacts the ejector block.

[0050] Raw materials 10 such as the polytetrafluoroethylene powder are placed in a space surrounded by the outer mold, the lower pressing disc, the lower mold, the core mold, etc. for the first time, and after material filling for the first time, the distance v1 from the material surface to the upper surface of the lower pressing disc is gx.

[0051] Material filling for the second time: the huff mold is placed in the outer mold, and at this time, the lower surface of the huff mold is superimposed with the material surface after material filling for the first time.

[0052] Refer to FIG. 2. Raw materials 10 such as the polytetrafluoroethylene powder are placed in a space surrounded by the outer mold, the lower pressing disc, the lower mold, the core mold, the huff mold, etc. for the second time, and after material filling for the second time, the distance v2 from the material surface to the upper surface of the huff mold is gx.

[0053] Material filling for the third time: the upper pressing disc is placed in the outer mold, and at this time, the lower surface of the upper pressing disc is superimposed with the material surface after material filling for the second time.

[0054] Refer to FIG. 3. Raw materials 10 such as the polytetrafluoroethylene powder are placed in a space surrounded by the outer mold, the lower pressing disc, the lower mold, the core mold, the huff mold, the upper pressing disc, etc. for the third time, and after material filling for the third time, the distance u2 from the material surface to the lower surface of the upper pressing disc is u1.

[0055] The upper mold axle journal with a smaller diameter of the upper mold extends into the upper pressing disc, and at the same time, the core mold extends into the through-hole of the upper mold. The lower surface of the upper mold is superimposed with the material surface after material filling for the third time. The distance t2 from the step face of the upper mold to the upper surface of the upper pressing disc is equal to t1. The upper end of the upper mold is connected to the upper pressing rod of the press.

[0056] 2), Primary Compression

[0057] Refer to FIGS. 2, 4 and 5. When the outer mold, the upper pressing disc and the lower pressing disc are kept motionless, the upper pressing rod which moves up and down drives the upper mold to move downward by a distance t2=e(x−1)/2, and at the same time, the lower ejecting rod which moves up and down drives, through the ejector block and the cushion block, the lower mold and the core mold to move upward by a distance t1=e(x−1)/2. At this time, the lower surface of the upper mold is leveled with the lower surface of the upper pressing disc, the step face of the upper mold contacts the upper surface of the upper pressing disc; and the upper surface of the lower mold is leveled with the upper surface of the lower pressing disc, the step face of the lower mold contacts the lower surface of the lower pressing disc.

[0058] 3), Secondary Compression

[0059] Refer to FIGS. 5 and 6. The outer mold is kept motionless; the upper pressing rod moves downward to drive the upper mold and the upper pressing disc to move downward together by a distance g (x−1), and at the same time, the lower ejecting rod moves upward to drive the ejector block, the cushion block, the core mold, the lower and lower pressing disc to move upward together by a distance g(x−1), so as to reach the required size of the I-shaped part. Therefore, the raw materials 10 are compressed to mold the I-shaped part 1.

[0060] 4), Demolding

[0061] Pressure maintaining is required for a period of time after secondary compression, and then demolding proceeds.

[0062] Refer to FIG. 7. The outer mold is kept motionless; the lower ejecting rod moves upward to drive the upper mold, the upper pressing disc, the huff mold, the lower mold, the lower pressing disc and the core mold to move upward together relative to the outer mold such that the I-shaped part is exposed of the outer mold; the upper mold and the upper pressing disc are taken down first, then the huff mold is taken down, and finally, the I-shaped part is taken down.