Smelting holding furnace for producing medical magnesium alloy

Abstract

The utility model belongs to the technical field of production devices of biomedical metal materials, and relates to a smelting holding furnace for producing medical magnesium alloy. The smelting and heat preserving furnace comprises a smelting furnace and a heat preserving furnace, the smelting furnace is communicated with the heat preserving furnace through a molten metal transfer pipe, a filter is arranged between the molten metal transfer pipe and the smelting furnace, a smelting furnace cover is arranged on the smelting furnace, and a heat preserving furnace cover is arranged on the heat preserving furnace. According to the magnesium alloy prepared by using the smelting holding furnace disclosed by the utility model, due to extremely few inclusions and hydrogen bubbles, unexpected early damage and degradation cannot occur, so that the original performance of the alloy is exerted, and the performance of a medical instrument can be exerted according to the design.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the production device's technical field of biological medical metal material relates to a kind of for the smelting holding furnace of medical magnesium alloy production. BACKGROUND

[0002] Currently, the main medical metal materials widely used in clinic include stainless steel, titanium alloy, cobalt-chromium alloy and the like. Such materials have superior corrosion resistance. However, this property also means that the metal materials will remain permanently in the human body, which poses risks such as postoperative inflammation for secondary surgery aimed at removing medical devices after healing and for medical devices difficult to remove.

[0003] To solve the risks existing in the current implantable medical devices, materials that can be absorbed after degradation in the human body have attracted wide attention. Among these materials, experts have high expectations for magnesium and magnesium alloys (hereinafter referred to as magnesium alloys), for the following reasons: (1) magnesium is a major element essential for the human body and is less likely to cause poisoning, with higher safety in the human body; (2) compared with non-degradable medical metals, the Young's modulus of magnesium alloys is most similar to that of human bones, which can effectively reduce stress shielding; (3) compared with polylactic acid materials, magnesium alloys have better mechanical properties. However, in order to make magnesium alloys suitable for implantable medical devices, their excessively fast degradation rate is considered a major problem to be overcome. After a more detailed analysis of this problem, experts found that magnesium alloys sometimes exhibit lower performance than the original performance of the alloy, resulting in undesirable damage and degradation in the early stage. This performance decline of magnesium alloys is caused by inclusions and hydrogen bubbles contained in the magnesium alloy. Molten magnesium alloy is prone to oxidation, and an oxide film is formed on the surface of the molten metal. After the oxide film precipitates in the molten metal, it becomes an inclusion mixed into the casting blank. In addition, the hydrogen gas solid solution amount of magnesium alloy is liquid > solid. Due to this difference, hydrogen elements will transfer from solid to liquid during solidification, and hydrogen gas bubbles will be generated when the hydrogen element exceeds the solid solution amount. Once the hydrogen gas bubbles dissipate in the atmosphere before the metal has completed solidification, hydrogen gas bubbles will form in the metal. For magnesium alloy parts used in larger industrial applications, the part size is relatively small, so it does not cause performance decline. However, since the parts of implantable medical devices are small, the magnesium alloy will gradually decrease with the degradation of the device, and the inclusions and hydrogen gas bubbles are relatively large, so they will cause the performance of the device to decrease. The excessively fast degradation rate of magnesium alloys, which is currently considered a problem, is fundamentally caused by the immaturity of production technology. SUMMARY

[0004] In view of the above-mentioned prior art defects, the purpose of the present application is to provide a smelting holding furnace for medical magnesium alloy production, which can avoid the problem of undesirable decline in magnesium alloy performance, thereby producing medical magnesium alloy materials with stable quality.

[0005] To achieve the above-mentioned objects and other related objects, the present application provides a smelting holding furnace for medical magnesium alloy production, which comprises a smelting furnace and a holding furnace, wherein the smelting furnace and the holding furnace are connected by a molten metal transfer pipe, a filter is arranged between the molten metal transfer pipe and the smelting furnace, a smelting furnace cover is arranged on the smelting furnace, and a holding furnace cover is arranged on the holding furnace.

[0006] In some embodiments of the present application, the outer diameter of the smelting furnace gradually decreases towards the bottom of the furnace.

[0007] In some embodiments of the present application, the smelting furnace comprises an inclined plane, which is connected with the molten metal transfer pipe.

[0008] In some embodiments of the present application, a molten metal outlet is arranged on the inclined plane, the molten metal transfer pipe is connected with the molten metal outlet, and the height of the molten metal outlet is more than 15% of the height from the bottom of the smelting furnace to the surface of the molten metal.

[0009] In some embodiments of the present application, a stirring mechanism is arranged in the smelting furnace cover.

[0010] In some embodiments of the present application, a first operation opening and closing window is arranged on the smelting furnace cover.

[0011] In some embodiments of the present application, a first gas pressurizing and depressurizing valve is arranged on the smelting furnace cover.

[0012] In some embodiments of the present application, a first thermocouple insertion hole is arranged on the smelting furnace cover.

[0013] In some embodiments of the present application, the molten metal transfer pipe is connected with the bottom of the holding furnace.

[0014] In some embodiments of the present application, a second operation opening and closing window is arranged on the holding furnace cover.

[0015] In some embodiments of the present application, a second gas pressurizing and depressurizing valve is arranged on the holding furnace cover.

[0016] In some embodiments of the present application, a second thermocouple insertion hole is arranged on the holding furnace cover.

[0017] In some embodiments of the utility model, the heat preservation furnace bottom is equipped with molten metal discharging mechanism.

[0018] In some embodiments of the utility model, the filter is made of a material that does not react with the molten magnesium alloy.

[0019] The utility model also provides a kind of using method of casting material for the smelting heat preservation furnace for medical magnesium alloy production as described above, comprising the following steps:

[0020] 1) foaming: after molten metal preparation is completed, inert gas is introduced into heat preservation furnace, smelting furnace is decompressed, and foaming treatment is carried out;

[0021] 2) molten metal transfer and filtration: after foaming operation, inert gas is introduced into smelting furnace, and pressure treatment is carried out in smelting furnace, and heat preservation furnace is decompressed;

[0022] 3) the acquisition of casting blank block: molten metal in heat preservation furnace is prepared into casting blank block.

[0023] The beneficial effects of the technical scheme of the utility model are as follows:

[0024] The magnesium alloy prepared by the smelting heat preservation furnace of the utility model has few inclusions and hydrogen bubbles, and does not cause undesirable early damage and degradation, so that the original performance of the alloy can be played, and thus the performance of medical devices can be played according to design. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 The structure schematic view of the smelting heat preservation furnace for medical magnesium alloy production of the utility model is shown.

[0026] Figure 2 The structure schematic view of the smelting heat preservation furnace used in the comparative example 1 of the utility model is shown.

[0027] REFERENCE NUMERALS IN DRAWINGS

[0028] 1 smelting furnace

[0029] 11 inclined plane

[0030] 12 molten metal outlet

[0031] 2 heat preservation furnace

[0032] 3 molten metal flow pipe

[0033] 4 filter

[0034] 5 smelting furnace cover

[0035] 51 stirring mechanism

[0036] 52 Open and close window for the first operation

[0037] 53 First gas pressure relief valve

[0038] 54 First thermocouple insertion hole

[0039] 6 Insulation furnace cover

[0040] 61 Open and close window for the second operation

[0041] 62 Second gas pressure relief valve

[0042] 63 Second thermocouple insertion hole

[0043] 7 Molten metal discharge mechanism

[0044] 8. Mold

[0045] 9. Anti-combustion gas introduction mechanism DETAILED DESCRIPTION

[0046] In the description of the present invention, it should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for understanding and reading by those familiar with the art, and are not intended to limit the conditions for the implementation of the present invention. Therefore, they have no technical significance. Any structural modifications, changes in proportional relationships, or adjustments in size should still fall within the scope of the technical content disclosed in the present invention without affecting the effects and objectives that can be achieved by the present invention. At the same time, the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the drawings and are only for the convenience of describing the present invention and simplifying the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore should not be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance.

[0047] In the description of this utility model, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections, electrical connections; direct connections, indirect connections through an intermediate medium, and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in this utility model based on specific circumstances.

[0048] Further, in the description of the present utility model, unless otherwise specified, the meaning of "a plurality of" is two or more than two.

[0049] As Figure 1 , the utility model discloses a kind of for medical magnesium alloy production smelting holding furnace, the smelting holding furnace includes smelting furnace 1 and holding furnace 2, the smelting furnace 1 and holding furnace 2 are communicated by molten metal transfer pipe 3, filter 4 is equipped between the molten metal transfer pipe 3 and smelting furnace 1, smelting furnace cover 5 is equipped on the smelting furnace 1, holding furnace cover 6 is equipped on the holding furnace 2.Inclusion and hydrogen element are the basic reason that the mechanical property and degradation characteristic of medical magnesium alloy occur decline, and by the utility model can effectively remove inclusion and hydrogen element, to prepare provide quality stable medical corrosion-resistant magnesium alloy.

[0050] In the smelting holding furnace for medical magnesium alloy production provided by the utility model embodiment, as Figure 1 , the outer diameter of the smelting furnace 1 gradually decreases towards the bottom of the smelting furnace 1.The advantage is that after a series of operations are completed, the molten metal will be left in the bottom of the smelting furnace 1, and then the molten metal cools and solidifies.The conical structure makes it easy to remove the molten metal from the smelting furnace 1, improving maintainability.

[0051] In the smelting holding furnace for medical magnesium alloy production provided by the utility model embodiment, as Figure 1 , the smelting furnace 1 includes an inclined plane 11, and the inclined plane 11 is connected with the molten metal transfer pipe 3.The advantage of being arranged as an inclined plane 11 is that the inclined effect is the same as above, i.e., to improve maintainability, and the purpose of the plane is to make the molten metal transfer pipe 3 facing the holding furnace 2 easily connected with the smelting furnace 1.In a specific embodiment, as Figure 1 , the inclined plane 11 extends from the bottom of the smelting furnace 1 to the middle part of the side wall of the smelting furnace 1.

[0052] In the smelting holding furnace for medical magnesium alloy production provided by the utility model embodiment, as Figure 1 , the inclined plane 11 is provided with a molten metal outlet 12, the molten metal transfer pipe 3 is connected with the molten metal outlet 12, and the height of the molten metal outlet 12 is more than 15% of the height from the bottom of the smelting furnace 1 to the surface of the molten metal.After the inclusion with a larger specific gravity is precipitated at the bottom, the filter 4 will suck it in during filtration.Through such a design, the service life of the filter 4 can be avoided to be reduced.

[0053] In the smelting holding furnace for medical magnesium alloy production provided by the utility model embodiment, as Figure 1 , the smelting furnace cover 5 is provided with a stirring mechanism 51.The stirring mechanism 51 can adopt an existing stirring mechanism, for example, including a stirring motor, a stirring shaft and a stirring paddle connected in sequence.

[0054] The melting holding furnace for producing medical magnesium alloy provided by the embodiment of the utility model has the advantages of Figure 1 The melting furnace cover 5 is provided with a first operation opening and closing window 52.

[0055] The melting holding furnace for producing medical magnesium alloy provided by the embodiment of the utility model has the advantages of Figure 1 The melting furnace cover 5 is provided with a first gas pressurizing and depressurizing valve 53.

[0056] The melting holding furnace for producing medical magnesium alloy provided by the embodiment of the utility model has the advantages of Figure 1 The melting furnace cover 5 is provided with a first thermocouple insertion hole 54, which facilitates the extension of the thermocouple from the melting furnace cover 5 to the melting furnace 1 through the first thermocouple insertion hole 54.

[0057] The melting holding furnace for producing medical magnesium alloy provided by the embodiment of the utility model has the advantages of Figure 1 The molten metal flow pipe 3 is communicated with the furnace bottom of the holding furnace 2.

[0058] The melting holding furnace for producing medical magnesium alloy provided by the embodiment of the utility model has the advantages of Figure 1 The holding furnace cover 6 is provided with a second operation opening and closing window 61.

[0059] The melting holding furnace for producing medical magnesium alloy provided by the embodiment of the utility model has the advantages of Figure 1 The holding furnace cover 6 is provided with a second gas pressurizing and depressurizing valve 62.

[0060] The melting holding furnace for producing medical magnesium alloy provided by the embodiment of the utility model has the advantages of Figure 1 The holding furnace cover 6 is provided with a second thermocouple insertion hole 63.

[0061] The melting holding furnace for producing medical magnesium alloy provided by the embodiment of the utility model has the advantages of Figure 1The bottom of the holding furnace 2 is provided with a molten metal discharge mechanism 7. The molten metal discharge mechanism 7 is, for example, a slidable shutter. When the molten metal moves to the holding furnace 2 through the molten metal shroud 3, the molten metal shroud 3 and the holding furnace 2 are in an open state. After a sufficient amount of molten metal moves to the holding furnace 2, the slidable shutter blocks the molten metal shroud 7. Thus, the backflow of the molten metal from the holding furnace to the shroud is suppressed. When the molten metal in the holding furnace 2 is to be discharged, the slidable shutter is slid so that the holding furnace 2 is connected to the outside. Thus, the molten metal is discharged.

[0062] In the melting holding furnace for medical magnesium alloy production according to the embodiments of the present application, the filter 4 should be made of a material that does not react with the molten magnesium alloy. The pore size and thickness, which are related to the filtering performance and service life, vary depending on the alloy composition, the cleanliness of raw materials, the melting conditions, and the like, and are also related to the inclusion content in the molten metal and the viscosity of the molten metal. Therefore, the filter 4 should be appropriately selected in consideration of the specific conditions. In some embodiments, the filter 4 can be made of magnesium oxide, for example. The filter 4 has a pore size of 100 to 1000 μm and a thickness of 30 to 50 mm.

[0063] The use of the melting holding furnace for medical magnesium alloy production according to the present application is as follows.

[0064] Bubbling: After the preparation of the molten metal, inert gas is introduced into the holding furnace 2. After the pressure reduction of the melting furnace 1, bubbling is performed. Through this operation, the inert gas, which has become fine bubbles, is injected into the molten metal in the melting furnace 1 through the filter 4. During the floating of the fine bubbles of the inert gas to the surface of the molten metal, the hydrogen element in the molten metal is captured and discharged to the outside from the surface of the molten metal. In order to prevent the discharged hydrogen element from being re-dissolved in the molten metal, the pressure reduction process is necessarily performed.

[0065] Transfer and filtration of the molten metal: After the bubbling operation, inert gas is introduced into the melting furnace 1, and pressure reduction is performed in the furnace. The holding furnace 2 is subjected to pressure reduction. Due to the pressure difference, the molten metal passes through the filter 4, the inclusions are filtered, and only the clean molten metal is transferred to the holding furnace 2. Since the molten metal is discharged from the bottom of the holding furnace 2, the roughness of the surface of the molten metal can be minimized, and inclusions can be prevented.

[0066] Obtaining of the casting blank: The molten metal in the holding furnace 2 is prepared into a casting blank by any method.

[0067] Release agent: A release agent can also be used as needed. The type of release agent should be selected so that it does not fall off and mix into the molten metal due to contact with the raw material or jig, or thermal shock. For example, boron nitride or titanium oxide can be selected, and the appropriate material should be selected with the contact time taken into account.

[0068] Material of the jig in contact with the molten metal: The material of the jig, such as a crucible, dross-out jig, stirring jig, or the like, which comes into direct contact with the molten metal, should be selected so that it does not cause the Mg component of the molten metal to dissolve out. For example, stainless steel, carbon, aluminum-plated steel, magnesium oxide, or the like can be selected, and the appropriate material should be selected with the contact time taken into account.

[0069] Example 1

[0070] Use Figure 2 A magnesium alloy molten metal was prepared using the apparatus shown in the figure, and a bubbling and filtration process was performed to obtain an evaluation sample from the molten metal after the filtration process. The smelting furnace 1 had a gradually decreasing outer diameter toward the bottom, and also had a partially inclined flat surface. The smelting furnace cover 5 had a stirring mechanism 51, an operation opening and closing window, a thermocouple insertion hole, and a gas pressure reducing valve. The gas pressure reducing valve was connected to a fire-resistant gas supply device, an inert gas supply device, and a pressure reducing pump, and was switchable. The inclined flat surface 11 of the smelting furnace 1 was connected to the molten metal transfer pipe 3, and a filter 4 was provided between the molten metal transfer pipe 3 and the smelting furnace 1. One end of the molten metal transfer pipe 3 was connected to the bottom of the holding furnace 2. The holding furnace cover 6 had an operation opening and closing window, a thermocouple insertion hole, and a gas pressure reducing valve. The gas pressure reducing valve was connected to a fire-resistant gas supply device, an inert gas supply device, and a pressure reducing pump, and was switchable. The holding furnace 2 and the molten metal transfer pipe 3 had a molten metal discharge mechanism 7.

[0071] Bubbling: The bubbling process was performed at a molten metal temperature of 680°C, and the inert gas was introduced for 10 minutes.

[0072] Filtration and transfer of the molten metal: This was performed at a molten metal temperature of 680°C.

[0073] Inclusion evaluation: The evaluation was performed by ultrasonic flaw detection. The results are shown in Table 1.

[0074] Hydrogen bubble evaluation: The evaluation was performed by hydrogen content analysis using Sn flux melting extraction. The results are shown in Table 2.

[0075] Comparative Example 1

[0076] Use Number of detected peaksThe illustrated device produces molten magnesium alloy metal, performs bubbling and filtering processes, and obtains an evaluation sample from the molten metal after the filtering process. The device is configured such that the smelting furnace 1 has a gradually decreasing outer diameter toward the bottom. The smelting furnace cover 5 is attached with a stirring and bubbling mechanism, a first work opening and closing window 52, a first thermocouple insertion hole 54, and a combustion gas prevention gas introduction mechanism 9. The stirring shaft and the stirring wings of the stirring and bubbling mechanism are hollow structures, and the stirring wings have a plurality of small holes at the tips. One end of the stirring shaft is connected to an inert gas supply mechanism, and inert gas bubbles can be injected into the molten metal by introducing inert gas. The smelting furnace 1 has a mechanism capable of tilting and pouring as a whole, and the molten metal flows out of the molten metal outlet 12 into the mold 8 and is cast into a shape. The filter 4 is provided above the mold 8, and the molten metal cast when the entire mold is heated will not solidify. After the molten metal that has passed through the filter 4 completely fills the mold 8, the molten metal can be solidified by stopping heating.

[0077] Bubbling: The bubbling process is performed at a molten metal temperature of 680°C, and the inert gas introduction time is 10 minutes.

[0078] Filtering and pouring: Performed at a molten metal temperature of 680°C. In order to compare with the example, the filter 4 does not utilize a pressure difference, but uses a filter hole that can pass through the weight of the molten metal itself.

[0079] Inclusion evaluation: Evaluated by ultrasonic flaw detection. The evaluation results are shown in Table 1.

[0080] Hydrogen bubble evaluation: Extracted by adding Sn flux and melting, and evaluated by hydrogen content analysis. The evaluation results are shown in Table 2.

[0081] Table 1

[0082] Example 1 ND Comparative Example 1 Hydrogen element content (ppm) 12

[0083] Table 2

[0084] Example 1 Comparative Example 1 8 ​ 23

[0085] In summary, the magnesium alloy prepared using the smelting and holding furnace of the present application has very few inclusions and hydrogen bubbles, and does not cause undesirable early damage and degradation, thereby exhibiting the performance of the alloy as designed, and thus the performance of the medical device can be exhibited.

[0086] In summary, the present application effectively overcomes the various shortcomings in the prior art and has high industrial utilization value.

[0087] The above embodiments only exemplarily illustrate the principles and effects of the present application, and are not used to limit the present application. Any person skilled in the art can modify or change the above embodiments without departing from the spirit and scope of the present application. Therefore, all equivalent modifications or changes completed by those skilled in the art without departing from the spirit and technical thought disclosed by the present application should be covered by the claims of the present application.

Claims

1. A smelting holding furnace for the production of medical magnesium alloys, characterized in that The smelting holding furnace comprises a smelting furnace (1) and a holding furnace (2), the smelting furnace (1) and the holding furnace (2) are communicated through a molten metal shroud (3), a filter (4) is arranged between the molten metal shroud (3) and the smelting furnace (1), a smelting furnace cover (5) is arranged on the smelting furnace (1), and a holding furnace cover (6) is arranged on the holding furnace (2).

2. The smelting holding furnace for producing a medical magnesium alloy according to claim 1, wherein The smelting furnace (1) gradually decreases in outer diameter towards the bottom of the furnace.

3. The smelting holding furnace for producing a medical magnesium alloy according to claim 1, wherein The smelting furnace (1) comprises an inclined plane (11) connected with the molten metal shroud (3).

4. The smelting holding furnace for producing a medical magnesium alloy according to claim 3, wherein The inclined plane (11) is provided with a molten metal outlet (12), the molten metal shroud (3) is communicated with the molten metal outlet (12), and the height of the molten metal outlet (12) is more than 15% of the height from the bottom of the smelting furnace (1) to the surface of the molten metal.

5. The smelting holding furnace for producing a medical magnesium alloy according to claim 1, wherein The smelting furnace cover (5) is provided with a stirring mechanism (51) inside; And / or, the smelting furnace cover (5) is provided with a first work opening and closing window (52) on the smelting furnace cover (5); And / or, the smelting furnace cover (5) is provided with a first gas pressure reducing valve (53) on the smelting furnace cover (5); And / or, the smelting furnace cover (5) is provided with a first thermocouple insertion hole (54) on the smelting furnace cover (5).

6. The smelting holding furnace for producing a medical magnesium alloy according to claim 1, wherein The molten metal shroud (3) is communicated with the bottom of the holding furnace (2).

7. The smelting holding furnace for producing a medical magnesium alloy according to claim 1, wherein The holding furnace cover (6) is provided with a second work opening and closing window (61) on the holding furnace cover (6).

8. The smelting holding furnace for producing a medical magnesium alloy according to claim 1, wherein The holding furnace cover (6) is provided with a second gas pressure reducing valve (62) on the holding furnace cover (6); And / or, the holding furnace cover (6) is provided with a second thermocouple insertion hole (63) on the holding furnace cover (6).

9. The smelting holding furnace for producing a medical magnesium alloy according to claim 1, wherein The holding furnace (2) is provided with a molten metal discharge mechanism (7) at the bottom.

10. The smelting holding furnace for producing a medical magnesium alloy according to claim 1, wherein The material of the filter (4) is a material that does not react with molten magnesium alloy.

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