Medium-frequency induction sintering furnace

Abstract

The invention provides a medium-frequency induction sintering furnace which comprises a shell, a heat preservation inner container is arranged in the shell, a crucible is arranged in the heat preservation inner container, a medium-frequency induction coil is arranged outside the crucible, a first air inlet is formed in the top of the shell, and a second air inlet is formed in the bottom of the heat preservation inner container. And an air outlet is formed in the bottom of the shell. The medium-frequency induction sintering furnace can effectively prevent the gas inlet in the upper portion of the furnace top from being blocked, smooth flowing of protective gas is guaranteed, and therefore the sintering effect is improved.

Description

Technical Field

[0001] The present invention belongs to the field of chemical engineering devices and relates to an intermediate frequency induction sintering furnace. Background Art

[0002] The intermediate frequency induction sintering furnace is a device widely used in the sintering of metal materials. Its working principle is that an electromagnetic field generated by an intermediate frequency induction coil causes an induced current in the metal materials in the furnace, thereby heating and sintering. During the sintering process, the flow direction of the protective gas has an important influence on the sintering effect. Usually, the protective gas enters the furnace through the upper part of the furnace top and then discharges from the lower part of the crucible to protect the atmosphere in the furnace from oxidation and at the same time carry away the impurities generated during the sintering process.

[0003] Currently, the gas inlet is from the upper part. If the gas inlet at the upper part of the furnace top is blocked, it may affect the flow direction of the protective gas, thereby affecting the sintering effect. In addition, since the inside of the furnace body is at the bottom of the crucible, hydrogen cannot fully enter the inside, resulting in slow internal gas circulation and difficulty in discharging impurities, causing volatiles to be unable to be discharged at the bottom and incomplete sintering. Summary of the Invention

[0004] To solve the technical problems existing in the prior art, the present invention provides an intermediate frequency induction sintering furnace, which can effectively avoid the blockage of the gas inlet at the upper part of the furnace top, ensure the smooth flow of the protective gas, and thus improve the sintering effect.

[0005] To achieve the above technical effects, the present invention adopts the following technical solutions:

[0006] The present invention provides an intermediate frequency induction sintering furnace, which includes a housing. Inside the housing, there is a heat preservation inner liner. Inside the heat preservation inner liner, there is a crucible. Outside the crucible, there is an intermediate frequency induction coil. At the top of the housing, there is a first gas inlet. At the bottom of the heat preservation inner liner, there is a second gas inlet. At the bottom of the housing, there is an air outlet.

[0007] In the present invention, the traditional gas inlet from the upper part of the furnace top is changed to simultaneous gas inlet from the upper part of the furnace top and the lower part of the crucible, which can effectively avoid the blockage of the gas inlet at the upper part of the furnace top, ensure the smooth flow of the protective gas, and thus improve the sintering effect.

[0008] As a preferred technical solution of the present invention, the number of the second gas inlets is not less than 1, such as 1, 2, 3, 4, or 5, etc., but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0009] As a preferred technical solution of the present invention, when the number of the second gas inlets is not less than 2, the second gas inlets are arranged equidistantly around the bottom of the heat preservation inner liner.

[0010] As a preferred technical solution of the present invention, the ratio of the intake rate of the protective gas at the first intake port to the total intake rate of the protective gas at the second intake port is 2 to 10:1, such as 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1 or 10:1, etc., but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0011] As a preferred technical solution of the present invention, the intake direction of the protective gas at the first intake port is parallel to the side wall of the crucible.

[0012] As a preferred technical solution of the present invention, the included angle between the intake direction of the protective gas at the second intake port and the intake direction of the protective gas at the first intake port is 120 to 180°, such as 120°, 130°, 140°, 145°, 150°, 160°, 170°, 175° or 180°, etc., but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0013] In the present invention, by controlling the flow rate ratio and intake direction of the protective gas at the first intake port and the second intake port, a good circulation effect of the protective gas in the furnace is ensured, so that the protective gas can be used under optimal conditions, thereby improving the utilization efficiency of the protective gas and reducing the production cost.

[0014] As a preferred technical solution of the present invention, the first intake port is connected to a first intake device, the second intake port is connected to a second intake device, and the first intake device and the second intake device are respectively independently connected to the control system.

[0015] As a preferred technical solution of the present invention, a sensor is provided inside the intermediate frequency induction sintering furnace, and the sensor is connected to the control system.

[0016] In the present invention, the sensor can be arranged in the space between the housing and the crucible, or can be arranged inside the crucible. The sensor can be a temperature sensor, a pressure sensor or an infrared sensor, etc. The infrared sensor can be used to monitor the content of impurity compounds.

[0017] As a preferred technical solution of the present invention, the air outlet is connected to an air extraction device.

[0018] As a preferred technical solution of the present invention, the air extraction device is connected to the control system.

[0019] In the present invention, by setting the sensor and the control system, the flow direction, flow rate and impurity content of the protective gas are monitored and adjusted in real time to ensure that the flow direction of the protective gas is correct, the flow rate is appropriate, and the impurity content is low, so as to ensure the stability and high efficiency of the sintering process.

[0020] In the present invention, by improving the design of the exhaust system, the protective gas can fully discharge impurities, thereby reducing the impurity content in the sintered blank and improving the performance uniformity of the sintered blank.

[0021] Compared with the prior art, the present invention has at least the following beneficial effects:

[0022] (1) The present invention provides an intermediate frequency induction sintering furnace, which can effectively avoid the blockage of the air inlet at the upper part of the furnace top, ensure the smooth flow of the protective gas, and thus improve the sintering effect;

[0023] (2) The present invention provides an intermediate frequency induction sintering furnace, which reduces the impurity content in the sintered blank and improves the performance uniformity of the sintered blank;

[0024] (3) The present invention provides an intermediate frequency induction sintering furnace, which has a stable and efficient sintering process, improves the utilization efficiency of the protective gas, and reduces the production cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a schematic structural diagram of the intermediate frequency induction sintering furnace provided in Embodiment 1 of the present invention;

[0026] In the figure: 1 - housing, 2 - heat preservation inner tank, 3 - first air inlet, 4 - air outlet, 5 - second air inlet, 6 - air extraction device, 7 - crucible.

[0027] The following further details the present invention. However, the following examples are merely simple examples of the present invention and do not represent or limit the scope of the protection of the present invention. The scope of protection of the present invention shall be subject to the claims. DETAILED DESCRIPTION OF THE INVENTION

[0028] To better illustrate the present invention and facilitate understanding of the technical solution of the present invention, the typical but non-limiting embodiments of the present invention are as follows:

[0029] Embodiment 1

[0030] This embodiment provides an intermediate frequency induction sintering furnace, and its structure is as Figure 1 shown. The intermediate frequency induction sintering furnace includes a housing 1, a heat preservation inner tank 2 is arranged inside the housing 1, a crucible 7 is arranged inside the heat preservation inner tank 2, an intermediate frequency induction coil is arranged outside the crucible 7, a first air inlet 3 is arranged at the top of the housing 1, two second air inlets 5 are arranged at equal intervals at the bottom of the heat preservation inner tank 2, and an air outlet 4 is arranged at the bottom of the housing 1;

[0031] The first air inlet 3 is connected to a first air inlet device, the second air inlet 5 is connected to a second air inlet device, and the first air inlet device and the second air inlet device are respectively independently connected to a control system;

[0032] There is a sensor inside the intermediate frequency induction sintering furnace, and the sensor is connected to the control system; the sensor is arranged in the space between the housing 1 and the heat preservation inner liner 2, and is arranged inside the crucible 7; the sensor includes a temperature sensor, a pressure sensor or an infrared sensor, and the infrared sensor is used to monitor the content of impurity compounds;

[0033] The air outlet 4 is connected to the air extraction device 6, and the air extraction device 6 is connected to the control system.

[0034] Application Example 1

[0035] The tungsten-nickel powder after cold isostatic pressing is sintered using the intermediate frequency induction sintering furnace provided in Example 1. The ratio of the intake rate of the protective gas at the first air inlet to the total intake rate of the protective gas at the second air inlet is 2:1. The intake direction of the protective gas at the first air inlet is parallel to the side wall of the crucible, and the included angle between the intake direction of the protective gas at the second air inlet and the intake direction of the protective gas at the first air inlet is 120°.

[0036] Application Example 2

[0037] The tungsten-nickel powder after cold isostatic pressing is sintered using the intermediate frequency induction sintering furnace provided in Example 1. The ratio of the intake rate of the protective gas at the first air inlet to the total intake rate of the protective gas at the second air inlet is 10:1. The intake direction of the protective gas at the first air inlet is parallel to the side wall of the crucible, and the included angle between the intake direction of the protective gas at the second air inlet and the intake direction of the protective gas at the first air inlet is 180°.

[0038] Application Example 3

[0039] The tungsten-nickel powder after cold isostatic pressing is sintered using the intermediate frequency induction sintering furnace provided in Example 1. The ratio of the intake rate of the protective gas at the first air inlet to the total intake rate of the protective gas at the second air inlet is 5:1. The intake direction of the protective gas at the first air inlet is parallel to the side wall of the crucible, and the included angle between the intake direction of the protective gas at the second air inlet and the intake direction of the protective gas at the first air inlet is 150°.

[0040] Application Example 4

[0041] The tungsten-nickel powder after cold isostatic pressing is sintered using the intermediate frequency induction sintering furnace provided in Example 1. The ratio of the intake rate of the protective gas at the first air inlet to the total intake rate of the protective gas at the second air inlet is 3:1. The intake direction of the protective gas at the first air inlet is parallel to the side wall of the crucible, and the included angle between the intake direction of the protective gas at the second air inlet and the intake direction of the protective gas at the first air inlet is 135°.

[0042] Application Example 5

[0043] The tungsten-nickel powder after cold isostatic pressing is sintered using the intermediate-frequency induction sintering furnace provided in Example 1. The ratio of the intake rate of the protective gas at the first intake port to the total intake rate of the protective gas at the second intake port is 8:1. The intake direction of the protective gas at the first intake port is parallel to the side wall of the crucible, and the included angle between the intake direction of the protective gas at the second intake port and the intake direction of the protective gas at the first intake port is 175°.

[0044] Comparative Application Example 1

[0045] In this comparative application example, except that the second intake port is closed and no protective gas is introduced, the other conditions are the same as those in Example 5.

[0046] Comparative Application Example 2

[0047] In this comparative application example, except that the ratio of the intake rate of the protective gas at the first intake port to the total intake rate of the protective gas at the second intake port is 1:1, the other conditions are the same as those in Example 5.

[0048] Comparative Application Example 3

[0049] In this comparative application example, except that the included angle between the intake direction of the protective gas at the second intake port and the intake direction of the protective gas at the first intake port is 105°, the other conditions are the same as those in Example 5.

[0050] In Application Examples 1-5 and Comparative Application Examples 1-3, the purity of tungsten powder is 99.9%, the purity of nickel powder is 99.8%, the mass ratio of tungsten powder to nickel powder is 95:5. Tungsten-nickel alloy blanks are prepared, using hydrogen as the protective gas. The sintering process is to hold at 800 °C for 1 h, hold at 1200 °C for 2 h, and hold at 1500 °C for 2 h. The content of impurity elements in the blanks is measured using ICP-AES, and the results are shown in Table 1.

[0051] Table 1

[0052] Impurity content Application Example 1 <0.08 wt% Application Example 2 <0.08 wt% Application Example 3 <0.08 wt% Application Example 4 <0.08 wt% Application Example 5 <0.08 wt% Comparative Application Example 1 >0.08 wt% Comparative Application Example 2 >0.08 wt% Comparative Application Example 3 >0.08 wt%

[0053] From the test results in Table 1, it can be seen that the impurity content in the sintered products obtained by sintering in Application Examples 1-5 is <0.08%, indicating that for the intermediate frequency induction sintering furnace provided by the present application, by introducing gas simultaneously from the upper part of the furnace top and the lower part of the crucible, it is possible to effectively avoid the blockage of the gas inlet at the upper part of the furnace top, ensure the smooth flow of the protective gas, and by controlling the flow rate ratio and the gas inlet direction of the protective gas at the first gas inlet and the second gas inlet, ensure that a good circulation effect of the protective gas is formed in the furnace, and effectively reduce the impurity content in the sintered product. In contrast, in Application Example 1, only the first gas inlet is introduced with the protective gas, which is relatively unfavorable for the derivation of impurity elements, resulting in an increase in the impurity content of the sintered product; in Application Example 2, the gas inlet rates of the first gas inlet and the second gas inlet are the same, which is not conducive to forming a protective gas circulation and is relatively unfavorable for the derivation of impurity elements, resulting in an increase in the impurity content of the sintered product; in Application Example 3, the gas inlet direction of the protective gas at the second gas inlet is smaller than that of the protective gas at the first gas inlet, which is not conducive to forming a protective gas circulation and is relatively unfavorable for the derivation of impurity elements, resulting in an increase in the impurity content of the sintered product.

[0054] The applicant declares that the present invention uses the above embodiments to illustrate the detailed structural features of the present invention, but the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvement to the present invention, the equivalent replacement of the components selected by the present invention, the addition of auxiliary components, the selection of specific methods, etc. all fall within the protection scope and the disclosure scope of the present invention.

[0055] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0056] In addition, it should be noted that, in the case of no contradiction, the various specific technical features described in the above specific embodiments can be combined in any suitable manner. To avoid unnecessary repetition, the present invention will not separately describe various possible combination methods.

[0057] In addition, any combination can be made between different embodiments of the present invention as long as it does not violate the idea of the present invention, and it should also be regarded as the content disclosed by the present invention.

Claims

1. A medium frequency induction sintering furnace, characterized in that: The medium frequency induction sintering furnace comprises a shell, a heat-insulating inner shell is arranged inside, a crucible is arranged inside the heat-insulating inner shell, a medium frequency induction coil is arranged outside the crucible, a first air inlet is arranged at the top of the shell, a second air inlet is arranged at the bottom of the heat-insulating inner shell, and an air outlet is arranged at the bottom of the shell.

2. The medium frequency induction sintering furnace according to claim 1, characterized in that: The number of the second air inlets is no less than one.

3. The medium frequency induction sintering furnace according to claim 2, characterized in that: When the number of the second air inlets is not less than 2, the second air inlets are arranged at equal intervals around the bottom of the thermal insulation liner.

4. The medium frequency induction sintering furnace according to claim 2, characterized in that: The ratio of the protective gas intake rate of the first air inlet to the total protective gas intake rate of the second air inlet is 2 to 10:

1.

5. The medium frequency induction sintering furnace according to claim 1, characterized in that: The inlet direction of the protective gas from the first gas inlet is parallel to the side wall of the crucible.

6. The medium frequency induction sintering furnace according to claim 5, characterized in that: The angle between the inlet direction of the protective gas through the second inlet and the inlet direction of the protective gas through the first inlet is 120-180°.

7. The medium frequency induction sintering furnace according to claim 1, characterized in that: The first air inlet is connected to a first air inlet device, the second air inlet is connected to a second air inlet device, and the first air inlet device and the second air inlet device are independently connected to a control system respectively.

8. The medium frequency induction sintering furnace according to claim 7, characterized in that: A sensor is arranged inside the medium frequency induction sintering furnace, and the sensor is connected to the control system.

9. The medium frequency induction sintering furnace according to claim 1, characterized in that: The air outlet is connected to an air extraction device.

10. The medium frequency induction sintering furnace according to claim 9, characterized in that: The air extraction device is connected to the control system.

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