Powder metallurgy mold for preparing thermoelectric materials

Abstract

The application discloses a powder metallurgy mould for preparing thermoelectric materials, and aims to solve the problems of low material utilization rate and much waste material caused by cutting of the formed thermoelectric materials. The application comprises a base, an outer mould cover in an oval ring structure and installed on the base, the thickness of the oval ring outer mould cover is uniform at each position, an inner mould cover installed in the outer mould cover, a rectangular mould cavity formed in the inner mould cover, and a press rod with a lower end inserted into the mould cavity for pressing the thermoelectric material powder loaded into the mould cavity. The powder metallurgy mould for preparing thermoelectric materials can improve the space utilization rate of the equipment and the material utilization rate of the mould, prepare large-size square crystal rods, effectively improve the preparation efficiency of the crystal rods, and is simple in subsequent slicing, generates less waste material, and can effectively improve the cutting efficiency and the material utilization rate.

Description

Technical Field

[0001] This invention relates to the field of thermoelectric semiconductors, and more specifically, to a powder metallurgy mold for preparing thermoelectric materials. Background Technology

[0002] Thermoelectric materials enable the direct conversion between heat and electrical energy, primarily used in solid-state refrigeration and waste heat power generation. They also have specialized applications in precision electronic devices, insulin storage, and high-end wine cabinets. Currently, the main commercial methods for preparing thermoelectric materials are zone melting and powder metallurgy. Thermoelectric materials prepared by zone melting exhibit uneven electrical properties and poor mechanical properties, resulting in low material utilization and short device lifespan, severely limiting their application range and scenarios. Powder metallurgy, mainly using hot pressing, employs graphite molds. While graphite molds offer good lubricity, their wear resistance and toughness are poor, making them unable to withstand the process parameters required for preparing large-size thermoelectric materials. Consequently, the prepared thermoelectric materials are small in size and have low production efficiency. Furthermore, thermoelectric materials prepared using graphite molds are often cylindrical, requiring subsequent slicing parallel to the cylindrical axis, which is inconvenient and generates significant waste material, further reducing material utilization. Summary of the Invention

[0003] To overcome the above shortcomings, the present invention provides a powder metallurgy mold for preparing thermoelectric materials, which can improve the utilization rate of equipment space and mold material, prepare large-size square crystal rods, effectively improve the preparation efficiency of crystal rods, and simplify subsequent slicing, generate less scrap, and also effectively improve cutting efficiency and material utilization.

[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: a powder metallurgy mold for preparing thermoelectric materials, comprising:

[0005] Base;

[0006] The outer mold sleeve has an elliptical ring structure and is mounted on the base;

[0007] The inner mold sleeve is installed inside the outer mold sleeve, forming a rectangular mold cavity inside the inner mold sleeve;

[0008] The pressure rod, with its lower end inserted into the mold cavity, is used to press the thermoelectric material powder loaded into the mold cavity.

[0009] In the preparation of thermoelectric material, the thermoelectric material powder is loaded into the mold cavity, the whole mold is placed in the heating furnace, then the pressing rod is pressed down, the thermoelectric material powder is pressed and formed in the mold cavity by heating and pressing. The shape of the mold is rectangular, so the pressed thermoelectric material is also rectangular, the subsequent slicing of the rectangular thermoelectric material is simple, the generation of edge scraps is less, and the cutting efficiency and material utilization can be improved. The outer film sleeve is in an elliptical ring structure, the wall thickness is uniform, compared with the circular outer film sleeve, the same size of thermoelectric material can be prepared, the use of mold material can be reduced, and the space utilization of the equipment can be improved.

[0010] The inner mold sleeve mainly plays a forming role and directly contacts the thermoelectric material, the inner mold sleeve is detachable and easy to separate from the thermoelectric material, the outer mold sleeve mainly plays a limiting role and bears the stress dispersed by the inner mold sleeve, during sintering, the elliptical ring-shaped outer mold sleeve bears the stress dispersed by the inner mold sleeve, the stress in each direction is balanced, and the outer mold sleeve is not easy to break.

[0011] The powder metallurgy mold for preparing thermoelectric material can improve the space utilization of the equipment and the utilization rate of the mold material, prepare large-size square crystal rods, effectively improve the preparation efficiency of the crystal rods, and the subsequent slicing is simple, the generation of edge scraps is less, and the cutting efficiency and material utilization can be effectively improved.

[0012] Preferably, the outer wall of the inner mold sleeve is in an elliptical structure, the inner wall of the inner mold sleeve is in a rectangular structure, and the four corner positions of the inner mold sleeve are cut to form four inner mold blocks.

[0013] The inner mold sleeve with the structure is convenient to install into the outer mold sleeve, and the four inner mold blocks are sequentially combined together, and the positioning is reliable.

[0014] Preferably, the upper end of the pressing rod is connected with a pressing cover.

[0015] The pressing cover is convenient for pressing the pressing rod.

[0016] Preferably, the bottom of the mold cavity is provided with a positioning plate, and the positioning plate is positioned with the lower part of the inner mold sleeve.

[0017] The positioning plate can improve the positioning reliability and accuracy of the inner mold sleeve.

[0018] Preferably, the lower end of the pressing rod is connected with an upper gasket, the bottom of the mold cavity is provided with a lower gasket, the corner position of the pressing rod is provided with a round corner, the corner position of the positioning plate is provided with a round corner, and the lower gasket is connected with the positioning plate; the upper gasket and the lower gasket are matched with the mold cavity.

[0019] The corner position of the positioning plate is provided with a round corner, which is convenient to install into the mold cavity. The corner position of the pressing rod is provided with a round corner, which is convenient to insert into the mold cavity. The lower gasket and the upper gasket make the lower end and the upper end accurate and reliable during the pressing process of the thermoelectric material.

[0020] Preferably, the outer sleeve and the inner sleeve are made of hard metal alloy.

[0021] The hard metal alloy has high compressive strength, bending strength and tensile strength.

[0022] Preferably, the thickness of the outer sleeve is 20-50mm.

[0023] The thickness of the outer sleeve is properly set to ensure the compressive strength, bending strength and tensile strength of the outer sleeve.

[0024] Preferably, the inner sleeve is provided with a positioning pin and a return spring at the bottom, the return spring abuts against the positioning pin, the edge of the positioning plate is provided with a receiving groove, one end of the positioning pin is arranged in the receiving groove, the other end of the positioning pin is obliquely arranged to form a pushing surface, and the edge of the lower gasket is supported on the positioning pin; a plurality of elastic pins are arranged on the pressing rod in an upper and lower interval, the end of the elastic pin is provided with an inclined guide surface, a positioning protrusion is arranged on the upper end of the inner sleeve, and the guide surface of the elastic pin slides over the positioning protrusion during the downward movement of the elastic pin along with the pressing rod, and the elastic pin abuts against the positioning protrusion during the upward movement of the elastic pin along with the pressing rod.

[0025] When the inner sleeve is arranged in the outer sleeve, the pushing surface abuts against the inner wall of the outer sleeve to push the positioning pin inward so that one end of the positioning pin is arranged in the receiving groove, and then the lower gasket is arranged in the mold cavity and the edge of the lower gasket is supported on the positioning pin. After the thermoelectric material powder is arranged in the mold cavity, the pressing rod is moved downward to press the thermoelectric material powder, and in this process, the guide surface of the end of the elastic pin slides over the positioning protrusion and does not be stuck. During the demolding operation, the pressing rod is moved upward, the elastic pin is positioned by abutting against the positioning protrusion, at this time, the inner sleeve is pulled upward together with the pressing rod, and the edge of the lower gasket is supported on the positioning pin, so that the thermoelectric material formed in the mold cavity and the inner sleeve are pulled upward together to be demolded. After the inner sleeve is completely separated from the outer sleeve, the positioning pin is moved outward under the action of the return spring to separate the positioning pin from the lower gasket, so that the formed thermoelectric material and the inner sleeve are separated.

[0026] Preferably, the inner sleeve is provided with a mounting hole corresponding to the positioning pin, one end of the mounting hole is connected with an end cover, the positioning pin is provided with a limiting protrusion, the return spring abuts against the limiting protrusion, the end of the positioning pin provided with the pushing surface can extend out of the end cover, and the length of the positioning pin extending into the receiving groove is less than the distance between the limiting protrusion and the end cover and less than the axial distance between the upper edge and the lower edge of the pushing surface of the positioning pin.

[0027] This structure facilitates the installation of the positioning pin.

[0028] Preferably, the pressing rod is provided with a connecting hole corresponding to the elastic pin, the end of the connecting hole is connected with a positioning ring, the elastic pin has a T-shaped structure, the elastic pin is connected with the connecting hole in a matched mode, the small-diameter end of the elastic pin extends out of the positioning ring, the guide surface is arranged on the small-diameter end of the elastic pin, a positioning spring is arranged in the connecting hole, and the positioning spring abuts against the elastic pin.

[0029] The elastic pin is installed steadily and reliably.

[0030] Compared with the prior art, the powder metallurgy mold for preparing thermoelectric material has the advantages that: (1) the powder metallurgy mold for preparing thermoelectric material can improve the space utilization of equipment and the utilization of mold material, prepare large-size square crystal rods, effectively improve the preparation efficiency of the crystal rods, and the subsequent slicing is simple, the generated corner materials are less, and the cutting efficiency and material utilization can be effectively improved; (2) the demolding operation of the formed thermoelectric material is convenient. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 is a top view of the present application;

[0032] Figure 2 is a sectional view of embodiment 1 of the present application;

[0033] Figure 3 is a sectional view of embodiment 2 of the present application;

[0034] Figure 4 is a partial enlarged view of the inner mold sleeve of embodiment 2 of the present application;

[0035] In the figure: 1, base, 2, outer mold sleeve, 3, inner mold sleeve, 4, mold cavity, 5, pressing rod, 6, inner mold block, 7, pressing cover, 8, positioning groove, 9, positioning plate, 10, mounting groove, 11, upper gasket, 12, lower gasket, 13, positioning pin, 14, return spring, 15, accommodating groove, 16, pushing surface, 17, elastic pin, 18, guide surface, 19, positioning protrusion, 20, positioning block, 21, mounting hole, 22, end cover, 23, limiting protrusion, 24, connecting hole, 25, positioning ring, 26, positioning spring. DETAILED DESCRIPTION

[0036] The technical solutions of the present application will be further specifically described below by means of specific embodiments and in combination with the drawings:

[0037] Embodiment 1: a powder metallurgy mold for preparing thermoelectric material (see attached Figure 1 , attached Figure 2 ), comprising:

[0038] a base 1;

[0039] an outer mold sleeve 2 in an oval ring structure and mounted on the base, the thickness of the oval ring outer mold sleeve is uniform at each position;

[0040] an inner mold sleeve 3 mounted in the outer mold sleeve, a rectangular mold cavity 4 is formed in the inner mold sleeve;

[0041] a pressing rod 5 inserted into the lower end of the mold cavity for pressing the thermoelectric material powder loaded into the mold cavity.

[0042] The outer wall of the inner mold sleeve is in an elliptical structure, the inner wall of the inner mold sleeve is in a rectangular structure, and four corners of the inner mold sleeve are cut to form four inner mold blocks 6. The upper end of the pressing rod is connected with a pressing cover 7, a positioning groove 8 is arranged on the lower end surface of the pressing cover, the upper end of the pressing rod is adaptively installed in the positioning groove, and the pressing cover is fixedly connected with the pressing rod. A positioning plate 9 is installed at the bottom of the mold cavity, and the positioning plate is sleeved and positioned with the lower part of the inner mold sleeve. An installation groove 10 is arranged on the base and corresponds to the position of the mold cavity, and the lower part of the positioning plate is adaptively installed in the installation groove. The lower end of the pressing rod is connected with an upper gasket 11, the bottom of the mold cavity is provided with a lower gasket 12, the corner part of the pressing rod is provided with a round corner, the corner part of the positioning plate is provided with a round corner, the lower gasket is connected to the positioning plate, and the upper gasket and the lower gasket are adapted to the mold cavity. The outer mold sleeve and the inner mold sleeve are made of hard metal alloy material, the hard metal alloy does not react and change phase with the thermoelectric material, can withstand high temperature and high pressure during sintering, and has high compression resistance, bending resistance and tensile strength. The thickness of the outer mold sleeve is 20mm-50mm, and the thickness of the outer mold sleeve in the embodiment is 30mm.

[0043] The thermoelectric material has a fixed compression ratio, and the final mold needs to be confirmed to have a minimum height through the expected square crystal bar height and the material compression ratio. If the size of the thermoelectric material is 300*30*50mm, according to the cold pressing compression ratio calculation, the height of the mold cavity is at least 85mm. The preparation efficiency and material cutting utilization rate of different sizes of thermoelectric materials are shown in Table 1.

[0044] Table 1

[0045] Material size / mm Mold material Production efficiency Material cutting utilization rate (1.5mm cutting) 30*30*150 Hard metal alloy 0.9KG / time 85% 30*60*300 Hard metal alloy 3.6KG / time 83% (30*20 Graphite 0.09KG / time 78%

[0046] From the data in Table 1, the larger the material preparation size, the more obvious the improvement in preparation efficiency, from 90g per time to 900G per time, and the material cutting utilization rate is improved from 78% to 85%.

[0047] Embodiment 2: A powder metallurgy mold for preparing thermoelectric material (see attached Figure 3 , attached Figure 4 ), which is similar in structure to Embodiment 1, and the main difference is that in this embodiment, the inner mold sleeve is provided with a positioning pin 13 and a return spring 14 at the bottom, the return spring abuts against the positioning pin, the edge of the positioning plate is provided with a containing groove 15, one end of the positioning pin is arranged in the containing groove, the other end of the positioning pin is arranged to form a pushing surface 16, and the edge of the lower gasket is supported on the positioning pin; a plurality of elastic pins 17 are arranged on the pressing rod, the end of the elastic pin is provided with an inclined guide surface 18, a positioning protrusion 19 is arranged on the upper end of the inner mold sleeve, the guide surface slides through the positioning protrusion during the downward movement of the elastic pin with the pressing rod, and the elastic pin abuts against the positioning protrusion during the upward movement of the elastic pin with the pressing rod. The positioning pin and the positioning protrusion are arranged on each inner mold block, the upper end of the inner mold block is provided with a positioning block 20, the positioning protrusion is arranged on the positioning block, and the positioning protrusion protrudes towards the pressing rod.

[0048] The inner mold sleeve is provided with an installation hole 21 corresponding to the positioning pin, one end of the installation hole is connected with an end cover 22, the positioning pin is provided with a limiting protrusion 23, a return spring abuts on the limiting protrusion, one end of the positioning pin provided with a pushing surface can extend out of the end cover, the length of the positioning pin extending into the accommodating groove is < the interval between the limiting protrusion and the end cover < the axial interval between the upper edge and the lower edge of the pushing surface of the positioning pin. The pressing rod is provided with a connecting hole 24 corresponding to the elastic pin, the end of the connecting hole is connected with a positioning ring 25, the elastic pin is in T-shaped structure, the elastic pin is connected with the connecting hole in a matched mode, the small-diameter end of the elastic pin extends out of the positioning ring, a guide surface is arranged on the small-diameter end of the elastic pin, a positioning spring 26 is installed in the connecting hole, and the positioning spring abuts on the elastic pin. The other structures are the same as those of the embodiment 1.

[0049] When the inner mold sleeve is installed into the outer mold sleeve, the pushing surface abuts on the inner wall of the outer mold sleeve, so that the positioning pin is pushed inward, and one end of the positioning pin is arranged in the accommodating groove, then the lower gasket is installed into the mold cavity, and the edge of the lower gasket is supported on the positioning pin. After the thermoelectric material powder is installed into the mold cavity, the pressing rod is moved downward to press the thermoelectric material powder, in the process, the guide surface of the end of the elastic pin slides through the limiting protrusion, and is not stuck. In the demolding operation, the pressing rod is moved upward, the elastic pin abuts on the limiting protrusion to be positioned, at this time, the inner mold sleeve is pulled upward together with the pressing rod, and the edge of the lower gasket is supported on the positioning pin, so that the thermoelectric material formed in the mold cavity is pulled upward together with the inner mold sleeve to be demolded. After the inner mold sleeve is completely separated from the outer mold sleeve, the positioning pin is moved outward under the action of the return spring, so that the positioning pin is separated from the lower gasket, and the separation of the formed thermoelectric material and the inner mold sleeve is facilitated.

[0050] The above-described embodiments are only the preferred schemes of the present application, and do not limit the present application in any form, and other variants and modifications can be made without exceeding the technical schemes recited in the claims.

Claims

1. A powder metallurgy mold for preparing thermoelectric materials, characterized in that, include: Base; The outer mold sleeve has an elliptical ring structure and is mounted on the base; The inner mold sleeve is installed inside the outer mold sleeve, forming a rectangular mold cavity inside the inner mold sleeve; The pressure rod, with its lower end inserted into the mold cavity, is used to press the thermoelectric material powder loaded into the mold cavity; A positioning plate and a lower shim are installed at the bottom of the mold cavity, and the lower end of the pressure rod is connected to the upper shim; a positioning pin and a return spring are installed at the bottom of the inner mold sleeve, with the return spring abutting against the positioning pin; the edge of the positioning plate is provided with a receiving groove, one end of the positioning pin is placed in the receiving groove, and the other end of the positioning pin is inclined to form a pushing surface; the edge of the lower shim is supported on the positioning pin; several spring pins spaced vertically are installed on the pressure rod, with an inclined guide surface at the end of the spring pin; a positioning protrusion is installed at the upper end of the inner mold sleeve; as the spring pin moves downward with the pressure rod, the guide surface slides over the positioning protrusion, and as the spring pin moves upward with the pressure rod, the spring pin abuts against the positioning protrusion.

2. The powder metallurgy mold for preparing thermoelectric materials according to claim 1, characterized in that, The outer wall of the inner mold sleeve has an elliptical structure, while the inner wall of the inner mold sleeve has a rectangular structure. The four corners of the inner mold sleeve are cut to form four inner modules.

3. The powder metallurgy mold for preparing thermoelectric materials according to claim 1, characterized in that, The upper end of the pressure rod is connected to the pressure cap.

4. The powder metallurgy mold for preparing thermoelectric materials according to claim 1, characterized in that, The positioning plate is fitted and positioned with the lower part of the inner mold sleeve.

5. The powder metallurgy mold for preparing thermoelectric materials according to claim 4, characterized in that, The corners of the pressure bar and the positioning plate are rounded, and the lower shim is connected to the positioning plate; both the upper and lower shims are adapted to the mold cavity.

6. A powder metallurgy mold for preparing thermoelectric materials according to any one of claims 1 to 5, characterized in that, Both the outer mold sleeve and the inner mold sleeve are made of hard metal alloy.

7. A powder metallurgy mold for preparing thermoelectric materials according to any one of claims 1 to 5, characterized in that, The thickness of the outer mold sleeve is 20mm-50mm.

8. The powder metallurgy mold for preparing thermoelectric materials according to claim 1, characterized in that, The inner mold sleeve has mounting holes corresponding to the positioning pins. One end of the mounting hole is connected to the end cap. The positioning pin has a limiting protrusion. The return spring abuts against the limiting protrusion. The end of the positioning pin with the pushing surface can extend out of the end cap. The length of the positioning pin extending into the receiving groove is less than the distance between the limiting protrusion and the end cap and less than the axial distance between the upper and lower edges of the pushing surface of the positioning pin.

9. A powder metallurgy mold for preparing thermoelectric materials according to claim 1, characterized in that, The pressure rod has a corresponding connecting hole for the spring pin. A positioning ring is connected to the end of the connecting hole. The spring pin has a T-shaped structure and is adapted to the connecting hole. The small diameter end of the spring pin extends out of the positioning ring. A guide surface is set at the small diameter end of the spring pin. A positioning spring is installed in the connecting hole and abuts against the spring pin.

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