CN219151575U - Hot extrusion die - Google Patents

Abstract

The utility model discloses a hot extrusion die, which comprises an upper die with an upper inner die cavity, a lower die matched with the upper die and provided with a lower inner die cavity, an upper die graphite insert and a lower die graphite insert, wherein the upper die graphite insert and the lower die graphite insert are respectively provided with a hollow cavity, and the upper die graphite insert is embedded in the upper inner die cavity; the lower die graphite insert is embedded in the lower inner die cavity; the upper internal mold cavity is communicated with the lower internal mold cavity, and the upper mold graphite insert is communicated with the lower mold graphite insert. According to the utility model, the upper die graphite insert and the lower die graphite insert which are high-temperature resistant, high-pressure resistant and excellent in heat conductivity are arranged, so that the die cannot be alloyed with thermoelectric raw materials in a co-melting reaction, the phenomenon that a sample cannot be demolded is avoided, the upper die graphite insert and the lower die graphite insert cannot be adhered to the inner walls of the corresponding upper die and lower die, and cannot be separated, the problem of demolding of a hot extruded sample is solved, and the condition that the die and the sample are scrapped is avoided; and the temperature difference between the inside and outside of the die is reduced, the thermal fatigue use damage is reduced, and the service life of the die is prolonged.

Description

Hot extrusion die

Technical Field

The utility model relates to the technical field of thermoelectric material preparation devices, in particular to a hot extrusion die.

Background

Currently, bismuth telluride base alloy thermoelectric materials are thermoelectric conversion materials with optimal performance in a room temperature range, and improving the grain orientation of the materials to improve the thermoelectric performance of bismuth telluride and the mechanical strength of the bismuth telluride base alloy thermoelectric materials to meet the fine cutting processing requirements is a key for improving the performance of miniature refrigeration devices.

One of the synthetic processes of the bismuth telluride material is a hot extrusion method, powder or block raw materials are placed into a die with a reducing inside, pressure is applied to the raw materials while heating, the raw materials pass through the reducing, shearing force is generated on the raw materials in a reducing area, grain refinement in the material is facilitated, and the preferential orientation of the grains is enhanced, so that the effects of improving the mechanical property and thermoelectric property of the material are achieved; in addition, the hot extrusion method has the advantages of stable process and strong repeatability, is suitable for mass production in the later period of research and development, and has considerable development value.

A common hot extrusion die is generally made of stainless steel alloy materials, and the following problems exist in use: 1. hot extrusion is typically a high temperature and pressure process, where if the thermoelectric raw materials have some or all of their components with low melting points, they may melt into one piece with the inner wall of the stainless steel alloy mold (contact portion alloying), eventually resulting in failure to demold, sample and mold rejection. 2. The use temperature of the hot extrusion method is generally in the range of 300-500 ℃, if the thermoelectric raw materials in the stainless steel alloy die are heated to reach the required process temperature, the temperature of the stainless steel die is 40-80 ℃ higher than the temperature of the thermoelectric raw materials in the die because of the difference of the thermal conductivities of the die materials and the thermoelectric raw materials, and if the temperature of the hot extrusion process is higher, the die is required to be at a higher working temperature, so that the thermal fatigue damage is more likely to occur, and the service life of the die is influenced.

Disclosure of Invention

The utility model aims to solve the technical problem of providing a hot extrusion die aiming at least one defect existing in the prior art.

The technical scheme adopted for solving the technical problems is as follows: the hot extrusion die comprises an upper die with an upper inner die cavity, a lower die matched with the upper die and provided with a lower inner die cavity, an upper die graphite insert and a lower die graphite insert, wherein the upper die graphite insert and the lower die graphite insert are respectively provided with a hollow cavity, and the upper die graphite insert is embedded in the upper inner die cavity; the lower die graphite insert is embedded in the lower inner die cavity; the upper inner die cavity is communicated with the lower inner die cavity, and the upper die graphite insert is communicated with the lower die graphite insert.

Further, it is preferable that the hot extrusion die further includes a temperature control unit disposed in the lower die graphite insert for heating the lower die graphite insert and controlling a heating temperature.

Further, preferably, the temperature control unit includes a heating element and a temperature measuring element, a first scarf joint groove and a second scarf joint groove are arranged in the side wall of the lower die graphite insert at intervals, and the heating element and the temperature measuring element are respectively accommodated in the first scarf joint groove and the second scarf joint groove.

Further, preferably, a first wiring groove and a second wiring groove are formed at the connection part of the upper die and the lower die, and the first wiring groove and the second wiring groove are respectively used for accommodating the wires of the heating element and the temperature measuring element.

Further, preferably, the upper inner die cavity comprises a first upper inner die cavity and a second upper inner die cavity which are arranged from top to bottom, the upper graphite insert is embedded in the second upper inner die cavity, and the inner wall surface of the upper graphite insert hollow cavity is flush with the inner wall surface of the first upper inner die cavity.

Further, preferably, the hot extrusion die further comprises an upper pressing piece, the upper pressing piece comprises an upper positioning column cap, an upper column shaft and a column head of a truncated cone structure extending from the upper column shaft, the upper positioning column cap is arranged outside the upper inner die cavity, the upper column shaft stretches into the upper inner die cavity, and the column head stretches into the lower die graphite insert.

Further, it is preferable that the hollow cavity in the lower die graphite insert comprises a reducing cavity and a non-reducing cavity extending downwards from the reducing cavity, and the inner diameter of the reducing cavity is gradually reduced from top to bottom.

Further, it is preferable that the lower internal mold cavity includes a first lower internal mold cavity and a second lower internal mold cavity arranged from top to bottom, and the lower mold graphite insert is embedded in the first lower internal mold cavity.

Further, preferably, the hot extrusion die further comprises a lower pressing piece, wherein the lower pressing piece comprises a lower positioning column cap and a lower column body extending from the lower positioning column cap, the lower positioning column cap is arranged outside the lower inner die cavity, and the lower column body extends into the lower inner die cavity.

Further, preferably, a positioning piece is arranged at the joint of the upper die and the lower die for positioning and fixing the upper die and the lower die.

Further, it is preferable that one of the upper die and the lower die is provided with a positioning groove, and the other one of the upper die and the lower die is provided with a positioning protrusion, and the positioning groove and the positioning protrusion are matched to form the positioning piece.

The utility model has the beneficial effects that: according to the hot extrusion die, the upper die graphite insert and the lower die graphite insert which are high-temperature resistant, high-pressure resistant and excellent in heat conductivity are respectively arranged in the upper die and the lower die which are made of stainless steel, graphite is an extremely high-temperature resistant material (the melting point is above 3000 ℃), so that the upper die graphite insert in the upper inner die cavity and the lower die graphite insert in the lower die cavity can completely exist stably at the temperature of a hot extrusion process, namely, the upper die graphite insert and the lower die cavity cannot be alloyed with thermoelectric raw materials by a co-melting reaction to cause that a sample cannot be demolded, and cannot be adhered to the inner walls of the upper die and the lower die which are made of stainless steel to cause that the sample cannot be demolded, the demolding problem of the hot extrusion sample is solved, and the condition that the die and the sample are scrapped is avoided; and the upper die graphite insert and the lower die graphite insert have excellent thermal conductivity, so that the temperature difference between the inside and outside of an upper inner die cavity and the inside and outside of a lower inner die cavity can be greatly reduced, the efficiency of heating thermoelectric raw materials is higher, and meanwhile, the upper die and the lower die which are made of stainless steel are at a temperature lower than the temperature required by a relative process, the thermal fatigue use damage is reduced, and the service life of the die is prolonged.

Drawings

FIG. 1 is an exploded view of a three-dimensional structure of a hot extrusion die of the present utility model;

FIG. 2 is an exploded cross-sectional view of a three-dimensional structure of a hot extrusion die of the present utility model;

FIG. 3 is a schematic perspective view of a hot extrusion die of the present utility model;

fig. 4 is a perspective structural sectional view of the hot extrusion die of the present utility model.

Detailed Description

For a clearer understanding of technical features, objects and effects of the present utility model, a detailed description of embodiments of the present utility model will be made with reference to the accompanying drawings.

1-4, the hot extrusion die comprises an upper die 10 with an upper inner die cavity 11 and a lower die 20 matched with the upper die 10 and provided with a lower inner die cavity 21, and further comprises an upper die graphite insert 30 and a lower die graphite insert 40 which are provided with hollow cavities, wherein the upper die graphite insert 30 is embedded in the upper inner die cavity 11; the lower die graphite insert 40 is embedded in the lower inner die cavity 21; the upper inner mold cavity 11 communicates with the lower inner mold cavity 21 and the upper mold graphite insert 30 communicates with the lower mold graphite insert 40.

The upper die 10 and the lower die 20 can be made of stainless steel alloy, an upper inner die cavity 11 and a lower inner die cavity 21 for loading are respectively arranged in the upper die and the lower die, the loading cavity diameter of the upper inner die cavity 11 is slightly larger than that of the lower inner die cavity 21, the hollow cavity in the lower die graphite insert 40 comprises a reducing cavity 41 and a non-reducing cavity 42 extending downwards from the reducing cavity 41, the inner diameter of the reducing cavity 41 is gradually reduced from top to bottom, the inner diameter of the non-reducing cavity 42 is unchanged, during use, thermoelectric materials are loaded into the upper inner die cavity 11 of the upper die 10, the thermoelectric materials enter the hollow cavity of the upper die graphite insert 30 from the upper inner die cavity 11 under the conditions of high temperature and high pressure, and are extruded into the hollow cavity of the lower die graphite insert 40, when reaching the lower die graphite insert 40, the thermoelectric materials pass through the reducing cavity 41 of the lower die graphite insert 40, meanwhile, the internal crystal grains are directionally refined under the action of the shearing force, and enter the non-reducing cavity 42 with smaller diameters, and finally the extruded thermoelectric material crystal bar is formed.

According to the hot extrusion die, the upper die graphite insert 30 and the lower die graphite insert 40 which are high-temperature resistant, high-pressure resistant and excellent in heat conductivity are respectively arranged in the upper die 10 and the lower die 20 which are made of stainless steel, graphite is an extremely high-temperature resistant material (the melting point is more than 3000 ℃), so that the upper die graphite insert 30 in the upper die cavity 11 and the lower die graphite insert 40 in the lower die 20 cavity can completely exist stably at the temperature of a hot extrusion process, namely, a sample cannot be demolded due to alloying with thermoelectric raw materials through a co-melting reaction, and the sample cannot be demolded due to adhesion with the inner walls of the upper die 10 and the lower die 20 which are made of stainless steel, so that the demolding problem of a hot extrusion sample is solved, and the condition that the die and the sample are scrapped is avoided; and the upper die graphite insert 30 and the lower die graphite insert 40 have excellent thermal conductivity, so that the temperature difference between the inside and the outside of the upper inner die cavity 11 and the lower inner die cavity 21 can be greatly reduced, the efficiency of heating thermoelectric raw materials is higher, and meanwhile, the upper die 10 and the lower die 20 which are made of stainless steel can be at a lower temperature than the temperature required by a relative process, the thermal fatigue use damage is reduced, and the service life of the die is prolonged.

In the prior art mold device, due to the difference of thermal conductivity of the mold material and the thermoelectric raw material, the temperature of the upper mold 10 and the lower mold 20 is 40-80 ℃ higher than the temperature inside the mold, and the mold is heated to a higher temperature for heating the raw material to the temperature required by the process, so that thermal fatigue damage is easy to occur, and the service life of the mold is influenced; to further address this issue, in some specific embodiments, the hot extrusion die further includes a temperature control unit 50, the temperature control unit 50 being disposed within the lower die graphite insert 40 for heating the lower die graphite insert 40 and controlling the heating temperature; the lower graphite mold insert 40 is heated by the lower graphite mold insert 40 inside the lower mold 20 to achieve the effect of heating the raw materials to the required process temperature, the lower graphite mold insert 40 has excellent thermal conductivity, the temperature difference between the lower graphite mold insert 40 and the raw materials can be greatly reduced (the controllable temperature difference is within 2-5 ℃, even almost no temperature difference is generated after long-time heating), the efficiency of heating the raw materials is higher, meanwhile, the upper mold 10 and the lower mold 20 on the outer side are prevented from being directly heated, the upper mold 10 and the lower mold 20 are at the temperature lower than the temperature required by the process, the thermal fatigue use damage is reduced, and the service lives of the upper mold 10 and the lower mold 20 are prolonged.

Further, it is preferable that the temperature control unit 50 includes a heating element 51 and a temperature measuring element 52, as shown in fig. 1, a first scarf joint groove 43 and a second scarf joint groove 44 are disposed in the side wall of the lower graphite mold insert 40 at intervals, the heating element 51 and the temperature measuring element 52 are respectively accommodated in the first scarf joint groove 43 and the second scarf joint groove 44, the first scarf joint groove 43 and the second scarf joint groove 44 can be disposed on two opposite side walls of the hollow cavity of the lower graphite mold insert 40, and heating and temperature control are more accurate; specifically, the heating element 51 may be a heating resistance wire, the temperature measuring element 52 may be a temperature thermocouple, the heating resistance wire is used for heating the lower graphite insert 40, the temperature thermocouple is used for detecting the internal temperature of the lower graphite insert 40, and the temperature data detected by the temperature measuring element 52 is used for controlling the heating resistance wire, so as to prevent overheating or prevent the process temperature from being not reached.

Further, it is preferable that the connection part between the upper mold 10 and the lower mold 20 is provided with a first wiring groove 22 and a second wiring groove 23, as shown in fig. 1, the first wiring groove 22 and the second wiring groove 23 are respectively used for accommodating the wires of the heating element 51 and the wires of the temperature measuring element 52. The wires of the heating element 51 and the temperature measuring element 52 are led out from the lower die graphite insert 40, the lower die 20 and the upper die 10 through the first wiring groove 22 and the second wiring groove 23 respectively, so that the whole die is convenient to install and use.

Further, the upper inner die cavity 11 includes a first upper inner die cavity 111 and a second upper inner die cavity 112, which are arranged from top to bottom, as shown in fig. 1 and 4, the outer diameter of the upper graphite die insert 30 is matched with the inner diameter of the second upper inner die cavity 112, the upper graphite die insert 30 is embedded in the second upper inner die cavity 112, the inner wall surface of the hollow cavity of the upper graphite die insert 30 is flush with the inner wall surface of the first upper inner die cavity 111, and the upper opening end of the first upper inner die cavity 111 is a feeding end for filling raw materials during use.

Further, it is preferable that the upper die 10 further includes an upper pressing piece 60, as shown in fig. 1, the upper pressing piece 60 for pressing the raw material entered into the first upper inner die cavity 111 so that the raw material moves toward the lower inner die cavity 21 below; specifically, the upper pressing piece 60 includes an upper positioning cap 61, an upper shaft 62 and a column head 63 of a truncated cone structure extending from the upper shaft 62, where the upper positioning cap 61 is disposed outside the upper inner mold cavity 11, so as to avoid difficult removal after being pressed with the upper mold 10; the diameter of the first upper inner die cavity 111 is matched with that of the upper column body 62, and the upper column body 62 stretches into the upper inner die cavity 11 to be matched with the inner wall of the first upper inner die cavity 111 and the inner wall of the upper die graphite insert 30 to be pressed into the pushing material; the post 63 extends into the lower die graphite insert 40.

Further, it is preferable that the hollow cavity in the lower die graphite insert 40 includes a reducing cavity 41 and a non-reducing cavity 42 extending downward from the reducing cavity 41, as shown in fig. 1 and 4, the inner diameter of the reducing cavity 41 is gradually reduced from top to bottom, and the reducing cavity 41 is configured such that the raw material is subjected to a larger shearing force under the action of high temperature and high pressure when passing through the reducing cavity 41. The raw materials after reducing extrusion are extruded to the lower end of a non-reducing cavity 42, the non-reducing cavity 42 is a material pressing forming area, and one end of the non-reducing cavity 42 is a discharge hole; preferably, the post 63 of the upper press 60 mates with the reducing cavity 41 of the lower graphite insert 40 such that the post 63 extends into the reducing cavity 41; when the thermoelectric material is used, the thermoelectric material is filled into the upper inner die cavity 11 of the upper die 10, under the pushing of the upper pressing piece 60, the thermoelectric material passes through the reducing cavity 41 when being pushed to the lower die 20 under the high-temperature and high-pressure condition, so that the internal grains of the material are directionally thinned, and then the thermoelectric material gradually enters the non-reducing cavity 42 with smaller diameter, and finally the thermoelectric material crystal bar after hot extrusion is formed.

Further, the lower inner cavity 21 preferably includes a first lower inner cavity 211 and a second lower inner cavity 212 arranged from top to bottom, as shown in fig. 1 and 4, the outer diameter of the lower graphite insert 40 is matched with the inner diameter of the first lower inner cavity 211, and the lower graphite insert 40 is embedded in the first lower inner cavity 211.

Further, the lower die 20 preferably further includes a hold down 80, as shown in fig. 1, the hold down 80 is used to hold down or assist in stressing the material to be hot extruded. The lower pressing piece 80 comprises a lower positioning column cap 81 and a lower column shaft 82 extending from the lower positioning column cap 81, wherein the lower positioning column cap 81 is arranged outside the lower inner die cavity 21, so that the lower positioning column cap is prevented from being difficult to take out after being pressed with the lower die 20; the lower shaft 82 extends into the lower inner die cavity 21, the outer diameter of the lower shaft 82 is matched with the inner diameter of the second lower inner die cavity 212, the outer diameter of the lower shaft 82 is also matched with the inner diameter of the non-reducing cavity 42 of the lower die graphite insert 40, and the lower shaft 82 extends into the non-reducing cavity 42 of the lower die graphite insert 40 through the second lower inner die cavity 212 to support the raw material to be hot extruded or assist the raw material to be hot extruded to bear force.

Further, it is preferable that a positioning member 70 is provided at the junction of the upper die 10 and the lower die 20, as shown in fig. 1, for positioning and fixing both. Further, it is preferable that one of the upper die 10 and the lower die 20 is provided with a positioning groove 71, and the other is provided with a positioning protrusion 72, and the positioning groove 71 and the positioning protrusion 72 are adapted to form a positioning member 70.

The use process of the hot extrusion die provided by the utility model is as follows: the lower die graphite insert 40 is firstly put into the first lower inner die cavity 211 of the lower die 20, and the lower pressing piece 80 penetrates to the non-reducing cavity 42 of the lower die graphite insert 40 through the second lower inner die cavity 212; the heating element 51 and the temperature measuring element 52 are arranged in the first embedding groove 43 and the second embedding groove 44 on the lower die graphite insert 40, and the wire parts are respectively led out from the first wiring groove 22 and the second wiring groove 23; the upper graphite insert 30 is installed in the upper second upper internal mold cavity 112, and the upper mold 10 and the lower mold 20 are integrated (tightly installed by matching the positioning groove 71 and the positioning protrusion 72); pouring powdery or blocky thermoelectric raw materials from the first upper inner die cavity 111, and pressing the upper pressing piece 60 into the first upper inner die cavity 111; putting the whole die into a vacuum device, vacuumizing (vacuum reaction can prevent raw materials from being oxidized), electrifying a heating piece 51 to heat a lower die graphite insert 40, detecting the temperature of the lower die graphite insert 40 (preventing insufficient temperature or overtemperature) through a temperature measuring piece 52, pressing an upper pressing piece 60 by using a hydraulic device after the temperature reaches the temperature required by the process, and applying the pressure required by the process to the raw materials until the raw materials are extruded from a non-reducing cavity 42 through a reducing cavity 41, thereby completing the hot pressing process; after the hot pressing is completed, the lower die graphite insert 40 is taken out, the lower pressing piece 80 is pressed into the non-reducing cavity 42 from one end of the reducing cavity 41, and the raw materials in the cavity are demoulded and taken out by applying pressure.

The above embodiments are provided to illustrate the technical concept and features of the present utility model and are intended to enable those skilled in the art to understand the content of the present utility model and implement the same according to the content of the present utility model, and not to limit the scope of the present utility model. All equivalent changes and modifications made with the scope of the claims should be covered by the claims.

Claims (11)

1. A hot extrusion die comprising an upper die (10) having an upper inner die cavity (11) and a lower die (20) having a lower inner die cavity (21) cooperating with the upper die (10), characterized in that the hot extrusion die further comprises an upper die graphite insert (30) and a lower die graphite insert (40) each having a hollow cavity, the upper die graphite insert (30) being embedded within the upper inner die cavity (11); the lower die graphite insert (40) is embedded in the lower internal die cavity (21); the upper inner mold cavity (11) is in communication with the lower inner mold cavity (21), and the upper mold graphite insert (30) is in communication with the lower mold graphite insert (40).

2. The hot extrusion die of claim 1, further comprising a temperature control unit (50), the temperature control unit (50) being disposed within the lower die graphite insert (40) for heating the lower die graphite insert (40) and controlling a heating temperature.

3. The hot extrusion die according to claim 2, wherein the temperature control unit (50) comprises a heating element (51) and a temperature measuring element (52), a first scarf joint groove (43) and a second scarf joint groove (44) are arranged in the side wall of the lower die graphite insert (40) at intervals, and the heating element (51) and the temperature measuring element (52) are respectively accommodated in the first scarf joint groove (43) and the second scarf joint groove (44).

4. A hot extrusion die according to claim 3, wherein a first wire groove (22) and a second wire groove (23) are formed at the joint of the upper die (10) and the lower die (20), and the first wire groove (22) and the second wire groove (23) are respectively used for accommodating the wires of the heating element (51) and the wires of the temperature measuring element (52).

5. The hot extrusion die according to claim 1, wherein the upper inner die cavity (11) comprises a first upper inner die cavity (111) and a second upper inner die cavity (112) which are arranged from top to bottom, the upper die graphite insert (30) is embedded in the second upper inner die cavity (112), and an inner wall surface of a hollow cavity of the upper die graphite insert (30) is flush with an inner wall surface of the first upper inner die cavity (111).

6. The hot extrusion die of claim 1, further comprising an upper press (60), the upper press (60) comprising an upper positioning cap (61), an upper shaft (62) and a boss (63) of a truncated cone structure extending from the upper shaft (62), the upper positioning cap (61) being disposed outside the upper inner die cavity (11), the upper shaft (62) extending into the upper inner die cavity (11), the boss (63) extending into the lower die graphite insert (40).

7. The hot extrusion die according to claim 1, wherein the hollow cavity within the lower die graphite insert (40) comprises a reducing cavity (41) and a non-reducing cavity (42) extending downwardly from the reducing cavity (41), the inner diameter of the reducing cavity (41) gradually decreasing from top to bottom.

8. The hot extrusion die according to claim 1, wherein the lower inner die cavity (21) comprises a first lower inner die cavity (211) and a second lower inner die cavity (212) arranged from top to bottom, the lower die graphite insert (40) being embedded within the first lower inner die cavity (211).

9. The hot extrusion die of claim 1, further comprising a lower press (80), the lower press (80) comprising a lower positioning cap (81) and a lower shaft (82) extending from the lower positioning cap (81), the lower positioning cap (81) being disposed outside the lower inner die cavity (21), the lower shaft (82) extending into the lower inner die cavity (21).

10. The hot extrusion die according to claim 1, wherein a positioning member (70) is provided at the junction of the upper die (10) and the lower die (20) for positioning and fixing the two.

11. The hot extrusion die according to claim 10, wherein one of the upper die (10) and the lower die (20) is provided with a positioning groove (71), the other one is provided with a positioning protrusion (72), and the positioning groove (71) and the positioning protrusion (72) are adapted to form the positioning member (70).

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