Powder pressing mold for preparing three-point bending strength test sample

Abstract

The utility model provides a powder pressing mold for preparing a three-point bending strength test sample, which comprises four parts, namely an upper mold, a middle mold, a lower mold and a demolding box. By designing the powder pressing die with the rectangular column body and the rectangular through hole charging groove, a plurality of samples for three-point bending strength testing can be pressed at one time, the time for manufacturing the samples for multiple times in repeated testing is shortened, and the testing work efficiency is improved.

Description

Technical Field

[0001] The utility model relates to a powder pressing mold, in particular to a powder pressing mold for preparing a three-point bending strength test sample. Background Art

[0002] Powder metallurgy molding is one of the basic processes in powder metallurgy production. Its purpose is to pressurize loose, difficult-to-form powders in a mold into a body with a certain geometric shape, size, density and strength. Using molds to press and form is the most commonly used method in powder metallurgy production, among which stainless steel molds are the most commonly used. Since the emergence of powder metallurgy molding technology, powder molding molds have been used more and more widely in the manufacturing industry, and there are more and more types.

[0003] Bending strength, also known as transverse rupture strength, refers to the ability of a material to resist bending without breaking. It is generally evaluated through two test methods, namely the three-point bending method and the four-point test method. Among them, the three-point bending method is simple to operate, convenient and accurate in calculation, and is the most commonly used method for testing the bending strength of materials. The three-point bending strength test is completed by a universal material testing machine. The standard specimens that have been ground and polished; such as the specimen with a span of 14.5mm, its length must be greater than 14.5mm, are freely placed on two fulcrums, and a short-term static force is applied at the midpoint of the span to break the specimen. Each group generally tests 5 data, and then the formula is used to calculate the average value.

[0004] It is a good choice to use powder forming molds to press out samples for bending strength testing. However, after sintering, the round, diamond, triangle, square and other embryos pressed out by the existing powder pressing molds need to be cut into specific sizes many times, and then polished before three-point bending strength testing can be performed. Moreover, only one test sample can be cut out at a time. When repeating the experiment many times, it is often necessary to make several more samples, which increases time and material costs.

[0005] Therefore, there is an urgent need for a device that can solve the problems of cumbersome and inefficient three-point bending strength test specimens. Utility Model Content

[0006] Based on the problems to be solved mentioned in the above background technology, the utility model proposes a powder pressing mold for preparing three-point bending strength test specimens. Aiming at the problems of cumbersome three-point bending strength test specimens and low work efficiency in actual work, the above-mentioned mold is used to simplify the process and improve efficiency, and the following technical solutions are implemented:

[0007] A powder pressing die for preparing a three-point bending strength test specimen comprises four parts, namely an upper die, a middle die, a lower die and a demoulding box. The bottom of the upper die has a rectangular column, the inside of the middle die is provided with a loading trough slidably connected to the column, the top of the lower die is fixedly sleeved with the bottom of the middle die, and the inside of the demoulding box is provided with a groove;

[0008] The side surfaces of the upper mold, middle mold, lower mold and demolding box are all cylindrical and have the same outer circle size. The outer diameter of the rectangular cylinder at the bottom of the upper mold is the same as the inner diameter of the charging groove inside the middle mold. The length of the rectangular cylinder needs to be slightly larger than the height of the through hole of the middle mold, preferably 1-3mm higher. This is to enable the pressed embryo to be completely ejected from the middle mold during demolding, which is convenient for demolding.

[0009] The upper end of the demoulding box has a circular groove, which is coaxial with the outer circular surface of the demoulding box and has a diameter 4-10mm smaller than the outer circular diameter of the demoulding box. The depth of the groove is 2-5mm smaller than the height of the demoulding box. The bottom of the demoulding box has a base with a diameter of 2-5mm. The four parts of the mold are all arc surfaces and are made of highly wear-resistant and corrosion-resistant steel.

[0010] The beneficial effects of the utility model are:

[0011] (1) By designing a powder pressing mold with a rectangular column and a rectangular through-hole loading trough slidably connected to the rectangular column, a long strip-shaped embryo is pressed out. After sintering, the long strip sample is cut into multiple samples of specific sizes, which are tested after grinding and polishing. One embryo is pressed at a time, and one sample can be cut out at one time. One embryo can be cut into multiple samples for multiple bending strength tests, which reduces the time and material cost of making test samples and improves work efficiency. In addition, compared with the dimensional defects of small diameter and large height of square columns, which easily cause stress concentration and lead to column fracture, the width and height of rectangular columns are close, and the above problems are not easy to occur;

[0012] (2) By providing a groove and a base, the discharged embryo body is received from the bottom of the middle mold, thereby facilitating embryo body recovery and improving pressing work efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is an exploded diagram of the main structure of this technology;

[0014] Figure 2 It is a schematic cross-sectional view of the main body of the present technology;

[0015] Figure 3 This is a schematic diagram of the rectangular column structure of this technology

[0016] Figure 1Middle: 1 upper mold, 2 rectangular cylinder, 3 rectangular through hole at the top of the middle mold, 4 middle mold, 5 lower box, 6 circular groove at the upper end of the demoulding box, 7 demoulding box. DETAILED DESCRIPTION

[0017] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0018] Example:

[0019] A powder pressing die for preparing a three-point bending strength test specimen comprises four parts, namely an upper die, a middle die, a lower die and a demoulding box. The bottom of the upper die has a rectangular column, the inside of the middle die is provided with a loading trough slidably connected to the column, the top of the lower die is fixedly sleeved with the bottom of the middle die, and the inside of the demoulding box is provided with a groove;

[0020] The side surfaces of the upper mold, middle mold, lower mold and demolding box are all cylindrical and have the same outer circle size. The outer diameter of the rectangular cylinder at the bottom of the upper mold is the same as the inner diameter of the charging groove inside the middle mold. The length of the rectangular cylinder needs to be slightly larger than the height of the through hole of the middle mold, preferably 1-3mm higher. This is to enable the pressed embryo to be completely ejected from the middle mold during demolding, which is convenient for demolding.

[0021] The upper end of the demoulding box has a circular groove, which is coaxial with the outer circular surface of the demoulding box and has a diameter 4-10mm smaller than the outer circular diameter of the demoulding box, and a depth of the groove 2-5mm smaller than the height of the demoulding box. The bottom of the demoulding box has a 2-5mm base. The four surfaces of the mold are all arc surfaces and are made of highly wear-resistant and corrosion-resistant steel.

[0022] The specific method of use is as follows: when in use, use the lower mold 5 as a support for the middle mold 4 to press the powder, place the lower mold 5 at the bottom of the middle mold 4, pour the powder from the rectangular through hole 3 at the upper end of the loading trough inside the middle mold 4, and then align the rectangular column 2 with the rectangular through hole 3 to ensure that the centers of the upper mold 1, the middle mold 4 and the lower mold 5 are aligned, and the powder is pressed into shape by applying pressure to the top of the upper mold 1, and then the lower mold 5 is removed, and the demolding box 7 is placed at the bottom of the middle mold, aligned again, and then the top of the upper mold 1 is continued to be pressurized so that the embryo is squeezed out of the through hole of the middle mold 4 and falls into the demolding box groove 6 to complete the demolding.

[0023] The above description is only a specific implementation method of the utility model. The above description does not limit the essential content of the utility model. Ordinary technicians in the relevant technical field can make improvements or modifications to the above specific implementation methods after reading this specification without departing from the essence and scope of the utility model. These improvements and modifications should also be regarded as the protection scope of the utility model.

Claims

1. A powder pressing die for preparing a three-point bending strength test specimen, characterized in that: It consists of an upper mold, a middle mold, a lower mold and a demoulding box; the bottom of the upper mold has a rectangular cylinder, the middle mold has a loading trough slidably connected to the rectangular cylinder, the top of the lower mold is fixedly sleeved with the bottom of the middle mold, and the demoulding box has a groove inside.

2. A powder pressing die for preparing a three-point bending strength test specimen according to claim 1, characterized in that: The side surfaces of the upper mold, middle mold, lower mold and demoulding box are all cylindrical and have the same outer circle size. The outer diameter of the rectangular cylinder is the same as the inner diameter of the charging trough, and the length of the rectangular cylinder is greater than the height of the middle mold through hole.

3. A powder pressing die for preparing a three-point bending strength test specimen according to claim 2, characterized in that: A circular groove is arranged at the upper end of the demoulding box, which is coaxial with the outer circumferential surface of the demoulding box, and the diameter of the circular groove is smaller than the outer diameter of the demoulding box, and the groove depth of the circular groove is smaller than the height of the demoulding box; a base is arranged at the bottom of the demoulding box.

4. A powder pressing die for preparing a three-point bending strength test specimen according to claim 3, characterized in that: The surfaces of the upper die, the middle die, the lower die and the demoulding box included in the powder pressing die are all arc surfaces and are all made of highly wear-resistant and corrosion-resistant steel.

5. A powder pressing die for preparing a three-point bending strength test specimen according to claim 4, characterized in that: The length of the rectangular column is 1-3 mm higher than the height of the through hole in the middle mold.

6. A powder pressing die for preparing a three-point bending strength test specimen according to claim 5, characterized in that: The diameter of the circular groove is 4-10 mm smaller than the outer diameter of the demoulding box. The depth of the circular groove is 2-5 mm smaller than the height of the demoulding box.

7. A powder pressing die for preparing a three-point bending strength test specimen according to claim 6, characterized in that: The base diameter of the bottom of the demoulding box is 2-5 mm.

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