A method and mold for preparing acetabular cup

Abstract

The present invention discloses a method and mold for preparing an acetabular cup, wherein the mold comprises a molding container and a base; the molding container comprises a bottom plate and a side wall, the bottom plate is provided with a first protrusion adapted to the groove of the acetabular cup, and an acetabular cup molding space is formed between the first protrusion and the side wall; the base comprises a second protrusion and a support member, the second protrusion can be snapped into the first protrusion; the interior of the second protrusion is a cavity, the support member snaps into the second protrusion and does not contact the second protrusion; the thermal conductivity coefficient of the first protrusion and the second protrusion is not less than 300W / (m·K). When preparing the acetabular cup, firstly, coolant is passed into the base, and then the molding container filled with slurry is placed on the base and frozen to obtain a blank. The blank is dried and sintered to obtain the acetabular cup. The present invention can produce an acetabular cup with gradient holes along the radial direction.

Description

Technical Field

[0001] The invention belongs to the technical field of porous ceramic preparation, and in particular relates to a method and a mold for preparing an acetabular cup. Background Art

[0002] Making the acetabular cup porous not only promotes adhesion to the surrounding bone and prevents loosening, but also reduces the elastic modulus of the prosthesis, thereby minimizing stress shielding. Currently, the most commonly used porous acetabular cup is a metal cup made using 3D printing technology.

[0003] Generally speaking, pore size affects the growth of different types of tissues, with pores of 5-15 μm favoring the growth of fibroblasts, pores of 70-120 μm favoring the growth of chondrocytes, and pores of 100-400 μm favoring bone regeneration.

[0004] However, due to the limited precision of 3D printing equipment, the current pore size of trabecular titanium is between 300-800μm, and this pore size range can only repair and reconstruct one type of tissue.

[0005] In recent years, silicon nitride has become a hot biomaterial due to its excellent properties, and the development of freeze-drying technology to produce porous ceramics has provided greater space for the preparation of gradient-pore silicon nitride acetabular cups.

[0006] However, the existing directional freezing method is to immerse the bottom of the metal mold in liquid nitrogen and use temperature transfer to achieve freezing. This method has the following problems: ① Liquid nitrogen evaporates very quickly at room temperature, so a large amount of liquid nitrogen will be consumed during the freezing process; ② A temperature-stable cold source cannot be obtained, and the pore size of the porous material prepared in this way cannot change uniformly, which will affect its mechanical properties; ③ Recently, studies have found that after the hemispherical acetabular cup is implanted in the human body, the main load-bearing point is concentrated near the middle or upper middle part, but due to heat transfer reasons, the temperature gradient during freezing will not be perfectly perpendicular to the bottom of the mold, but slightly inclined. The existing method will make the temperature gradient in the center lower than that on both sides, so the slurry volume change in the middle part will be limited when both sides are frozen, which will lead to certain defects in the center part, which is inconsistent with the load-bearing characteristics of the acetabular cup. Summary of the Invention

[0007] The purpose of the present invention is to provide a mold for preparing an acetabular cup, which can save coolant and achieve a temperature gradient in the radial direction. The temperature of the center part at the same radial position will not become the highest temperature point, so that the silicon nitride acetabular cup produced is conducive to its force and fixation in the human body. The radius refers to the radius of the hemispherical acetabular cup.

[0008] To achieve the above object, the technical solution adopted by the present invention is:

[0009] A mold for preparing an acetabular cup comprises a molding container and a base;

[0010] The molding container includes a bottom plate and a side wall, wherein the bottom plate is provided with a first protrusion adapted to the acetabular cup groove, and an acetabular cup molding space is formed between the first protrusion and the side wall;

[0011] The base includes a second protrusion and a support member, and the second protrusion can be snapped into the first protrusion;

[0012] The interior of the second protrusion is a cavity, and the support member is inserted into the second protrusion without contacting the second protrusion;

[0013] The thermal conductivity of the first protrusion and the second protrusion is not less than 300 W / (m·K).

[0014] The beneficial effects of this technical solution are:

[0015] The first protrusion and the second protrusion are both hemispherical, the same shape as the acetabular cup, and have high thermal conductivity. When using this mold to freeze the slurry, a temperature gradient can be obtained along the radius of the acetabular cup. The slurry close to the cold surface generates a large number of tiny crystal nuclei under an excessively high temperature gradient. Due to the large number of crystal nuclei and the short freezing time, the crystal growth is inhibited. Therefore, the crystal size of the frozen crystals close to the cold surface is small, and the corresponding position of the acetabular cup is denser and has good mechanical properties. The crystal size is large at the position away from the cold surface, and the porosity of the corresponding position of the acetabular cup is high, which is conducive to the growth of bone tissue. The pore size of the prepared acetabular cup changes continuously along the radius direction, and the overall mechanical properties are good.

[0016] Preferably, a guide member is provided on the base at an outer side relative to the side wall; and a stabilizing member for stabilizing the bottom plate is provided on the base.

[0017] The beneficial effects of adopting this preferred solution are: when the molding container is placed on the base, the guide member can enable it to be placed accurately and quickly to avoid affecting the direction of the temperature gradient due to inaccurate placement; different guide members can be selected according to different ways of passing the coolant. If the coolant is circulated in an immersion manner, the guide member can be sleeve-shaped. After the molding container and the base are combined, the sleeve-shaped guide member is sleeved on the molding container and at the same time serves to isolate the molding container from the coolant. If the coolant is not circulated in an immersion manner, the guide member can be a simple rod-shaped member, and more than three rods are used to guide the molding container to be accurately placed on the base; when the second protrusion is inserted into the first protrusion, the stabilizing member can contact the bottom to stabilize the combination of the molding container and the base. On the other hand, the stabilizing member can be flexibly or fixedly connected to the support member so that regardless of whether there is a connecting device between the second protrusion and the support member, the second protrusion can be prevented from directly contacting the support member to facilitate the passage of coolant.

[0018] Preferably, the thermal conductivity of the bottom plate and the side wall is less than 0.05 W / (m·K)

[0019] The beneficial effect of adopting this preferred solution is that the bottom plate and side walls are made of insulating materials with low thermal conductivity, which can avoid cooling in directions other than the radius of the acetabular cup and avoid affecting the temperature gradient in the radial direction.

[0020] Preferably, a plurality of clamping strips are provided between the second protrusion and the support member, and the clamping strips divide the space between the second protrusion and the support member into a plurality of coolant channels.

[0021] The beneficial effects of adopting this preferred solution are: on the one hand, the clamping strip divides the gap between the second protrusion and the support member into several coolant channels, making it easier for the coolant to climb the slope when flowing in the gap; on the other hand, the clamping strip can play a supporting role, supporting the second protrusion from directly contacting the support member.

[0022] Preferably, a second channel is provided inside the support member, one end of the second channel is connected to the center of the gap formed between the second protrusion and the support member, and the refrigerant flows into the second channel and flows out through the gap formed between the second protrusion and the support member.

[0023] The beneficial effects of adopting this preferred solution are: the center of the gap formed between the second protrusion and the support member is connected to the second channel, and the coolant enters the gap formed between the second protrusion and the support member through the second channel, that is, the center of the gap is the lowest temperature point, the crystal size is smaller and more, the intermediate crystallization rate is faster, and the volume change will not be restricted, so the middle part of the ceramic material finally obtained will not have defects and will be denser, with better mechanical properties, and more in line with the load-bearing characteristics of the acetabular cup.

[0024] Preferably, the support member is further provided with a third channel, so that the coolant flowing out from the gap formed between the second protrusion and the support member flows into the third channel.

[0025] The beneficial effect of adopting this preferred solution is: since the refrigerant flows out from the gap formed between the second protrusion and the support member from the center to the periphery, if it is inconvenient to directly recover the refrigerant, after setting the third channel on the support member, an outlet can be set for unified recovery, which is more convenient.

[0026] Preferably, the inner diameter of the second channel is 2-8 times the distance between the second protrusion and the support member.

[0027] The beneficial effect of adopting this preferred solution is that since the refrigerant will be diverted along the curved surface after flowing from the second channel to the gap formed between the second protrusion and the support member, this preferred solution allows the refrigerant to contact the second protrusion when flowing through the gap, which is beneficial to the formation of a temperature gradient in the radial direction of the acetabulum cup.

[0028] Preferably, the distance between the second protrusion and the support member gradually decreases from the center to the periphery.

[0029] The beneficial effect of adopting this preferred solution is: since the refrigerant flows from the center to the periphery when flowing through the gap between the second protrusion and the support member, the area it flows through gradually increases, but the refrigerant does not increase. Reducing the distance between the two allows the refrigerant to always contact the second protrusion.

[0030] Preferably, a plurality of baffles are provided on the surface of the support member facing the second protrusion.

[0031] The beneficial effect of adopting this preferred solution is: since the refrigerant flows from the center to the periphery in the gap between the second protrusion and the support member, the area it flows through gradually increases, but the refrigerant does not increase. By setting a baffle, the refrigerant can always contact the second protrusion.

[0032] A method for preparing an acetabular cup comprises the following steps:

[0033] Passing a coolant having a temperature of -10 to 20° C. into the base of the mold for preparing the acetabular cup;

[0034] The solvent is that the slurry of camphene is added to a forming container, and frozen for more than 30 minutes to obtain a blank;

[0035] The acetabular cup can be obtained by drying and sintering the blank.

[0036] The beneficial effects of this technical solution are:

[0037] By using a dedicated freezing mold and controlling the coolant temperature, a larger temperature gradient distributed along the radial direction can be obtained, so that the pore size distribution range in the radial direction of the acetabular cup is large, providing an environment for the ingrowth of different bone tissues; this method can obtain an acetabular cup with a high porosity, avoiding stress shielding caused by excessive elastic modulus. In addition, the pore size changes continuously along the radial direction, so that the mechanical properties of the acetabular cup are better when the porosity is larger; using camphene as a solvent, through holes connected along the radial direction can be obtained, which is more conducive to the ingrowth of bone tissue. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a schematic diagram of the overall structure of Example 1 of the present invention;

[0039] Figure 2 is a vertical cross-sectional view of the molded container in Example 1 of the present invention;

[0040] Figure 3 is a cross-sectional view of the base along the vertical direction in Example 2 of the present invention;

[0041] Figure 4 This is a vertical cross-sectional view of a base in a preferred embodiment of Example 3 of the present invention;

[0042] Figure 5 This is a vertical cross-sectional view of the base of another preferred embodiment of Example 3 of the present invention.

[0043] 1 is a molding container, 2 is a guide member, 3 is a base, 4 is a side wall of the molding container, 5 is a first protrusion, 6 is a bottom plate, 7 is a second protrusion, 8 is a support member, 9 is a stabilizing member, 10 is a second channel, 11 is a third channel, and 12 is a baffle. DETAILED DESCRIPTION

[0044] To make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings and examples.

[0045] Example 1

[0046] A mold for preparing an acetabular cup in this embodiment,

[0047] For reference Figure 1 and Figure 2 , comprising a molding container and a base, the molding container comprising a bottom plate and a side wall, the bottom plate being provided with a first protrusion adapted to the acetabular cup groove, the first protrusion and the side wall forming an acetabular cup molding space, the thermal conductivity of the bottom plate and the side wall being less than 0.05 W / (m·K);

[0048] The base includes a second protrusion and a support member, wherein the second protrusion can be snapped into the first protrusion; a guide member is provided on the base relative to the outer side of the side wall, and a stabilizing member for stabilizing the bottom plate is provided on the base;

[0049] The interior of the second protrusion is a cavity, and the support member is inserted into the second protrusion without contacting the second protrusion; the thermal conductivity coefficient of the first protrusion and the second protrusion is not less than 300 W / (m·K).

[0050] As a preferred solution, a plurality of clamping strips are provided between the second protrusion and the support member, and the clamping strips divide the space between the second protrusion and the support member into a plurality of cooling liquid channels.

[0051] As a preferred embodiment, a second channel is provided inside the support member, one end of the second channel is connected to the center of the gap formed between the second protrusion and the support member, and the refrigerant flows into the second channel and then flows out through the gap formed between the second protrusion and the support member. The inner diameter of the second channel is 2-8 times the distance between the second protrusion and the support member. The support member is further provided with a third channel, so that the coolant flowing out of the gap formed between the second protrusion and the support member flows into the third channel;

[0052] As a preferred solution, the distance between the second protrusion and the support member gradually decreases from the center to the periphery.

[0053] As a preferred solution, a plurality of baffles are provided on the surface of the support member facing the second protrusion.

[0054] This embodiment also provides a method for preparing an acetabular cup, comprising the following steps:

[0055] Passing a coolant having a temperature of -10 to 20° C. into the base of any of the above-mentioned molds for preparing an acetabular cup;

[0056] After adding a slurry containing camphene as a solvent into a molding container, the molding container is placed on a base and frozen to obtain a blank;

[0057] The acetabular cup can be obtained by drying and sintering the blank.

[0058] Example 2

[0059] A mold for preparing an acetabular cup in this embodiment,

[0060] Combine Figure 3 As shown, it includes a molding container and a base, the molding container includes a bottom plate and a side wall, the bottom plate is provided with a first protrusion adapted to the acetabular cup groove, the first protrusion and the side wall form an acetabular cup molding space, and the thermal conductivity of the bottom plate and the side wall is less than 0.05 W / (m·K);

[0061] The base includes a second protrusion and a support member, wherein the second protrusion can be snapped into the first protrusion; a guide member is provided on the base relative to the outer side of the side wall, and a stabilizing member for stabilizing the bottom plate is provided on the base;

[0062] The interior of the second protrusion is a cavity, and the support member is inserted into the second protrusion without contacting the second protrusion; the thermal conductivity coefficient of the first protrusion and the second protrusion is not less than 300 W / (m·K).

[0063] A plurality of clips are provided between the second protrusion and the support member, and the clips divide the space between the second protrusion and the support member into a plurality of coolant channels.

[0064] As a preferred solution, one of the cooling liquid channels passes through the center of the top of the acetabular cup, and the other cooling liquid channels are evenly distributed on both sides of the cooling liquid channel and are parallel to the channel.

[0065] When using the mold of the acetabular cup of the present embodiment, coolant is introduced from the coolant channel on one side of the base, the slurry is added to the molding container, and the molding container is quickly placed on the base so that the second protrusion on the base is just stuck in the first protrusion, thereby forming a temperature gradient in the radial direction of the acetabular cup; on the one hand, the clamping strip divides the interval between the second protrusion and the support member into several coolant channels, making it easier for the coolant to climb the slope when flowing in the interval, so as to prevent the top center position of the acetabular cup from not being cooled as soon as possible; on the other hand, the clamping strip can play a supporting role, supporting the second protrusion from directly contacting the support member.

[0066] Example 3

[0067] A mold for preparing an acetabular cup in this embodiment,

[0068] Combine Figure 4 and Figure 5 As shown, it includes a molding container and a base, the molding container includes a bottom plate and a side wall, the bottom plate is provided with a first protrusion adapted to the acetabular cup groove, the first protrusion and the side wall form an acetabular cup molding space, and the thermal conductivity of the bottom plate and the side wall is less than 0.05 W / (m·K);

[0069] The base includes a second protrusion and a support member, wherein the second protrusion can be snapped into the first protrusion; a guide member is provided on the base relative to the outer side of the side wall, and a stabilizing member for stabilizing the bottom plate is provided on the base;

[0070] The interior of the second protrusion is a cavity, and the support member is inserted into the second protrusion without contacting the second protrusion; the thermal conductivity coefficient of the first protrusion and the second protrusion is not less than 300 W / (m·K).

[0071] A second channel is provided inside the support member, one end of the second channel is connected to the center of the gap formed between the second protrusion and the support member, and the refrigerant flows into the second channel and then flows out through the gap formed between the second protrusion and the support member. The inner diameter of the second channel is 2-8 times the distance between the second protrusion and the support member. The support member is further provided with a third channel, so that the coolant flowing out of the gap formed between the second protrusion and the support member flows into the third channel;

[0072] As a preferred solution, the distance between the second protrusion and the support member gradually decreases from the center to the periphery.

[0073] As a preferred solution, a plurality of baffles are provided on the surface of the support member facing the second protrusion.

[0074] When the mold of the acetabular cup of the present embodiment is used, the coolant is introduced from the second channel. After flowing through the second channel, the coolant enters the center position between the second protrusion and the support member, and then is diverted to the surroundings. Finally, the diverted coolant flows into the third channel and flows out of the base. Since the temperature of the coolant just entering the base is the lowest, the coolant first contacts the middle position of the second protrusion after passing through the second channel, so the temperature of the middle position of the second protrusion is the lowest. The volume of the slurry in the corresponding radial direction will not be limited when freezing. The center position of the acetabular cup finally obtained is free of defects and has the best mechanical properties. After the acetabular cup is implanted in the human body, the center part serves as the most important bearing point, and its pressure resistance and wear resistance are better than other parts.

[0075] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in this field should understand that they can still modify the technical solutions described in the above embodiments, or replace some of the technical features therein with equivalents; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A mold for preparing an acetabular cup, characterized in that: The molding container comprises a molding container and a base; the molding container comprises a bottom plate and a side wall, the bottom plate is provided with a first protrusion adapted to the acetabular cup groove, and an acetabular cup molding space is formed between the first protrusion and the side wall; The base includes a second protrusion and a support member, the second protrusion can be snapped into the first protrusion; the interior of the second protrusion is a cavity, and the support member is snapped into the second protrusion without contacting the second protrusion; The thermal conductivity of the first protrusion and the second protrusion is not less than 300 W / (m·K); A second channel is provided inside the support member, one end of the second channel is connected to the center of the gap formed between the second protrusion and the support member, and the refrigerant flows into the second channel and then flows out through the first gap; The support member is further provided with a third channel, so that the coolant flowing out of the gap formed between the second protrusion and the support member flows into the third channel; A guide piece is provided on the base at an outer side of the side wall, and a stabilizing piece for stabilizing the bottom plate is provided on the base.

2. The mold for preparing an acetabular cup according to claim 1, wherein: The thermal conductivity of the bottom plate and the side wall is less than 0.05 W / (m·K).

3. The mold for preparing an acetabular cup according to claim 1, wherein: A plurality of clamping strips are provided between the second protrusion and the support member, and the clamping strips divide the interval between the second protrusion and the support member into a plurality of cooling liquid channels.

4. The mold for preparing an acetabular cup according to claim 1, wherein: An inner diameter of the second channel is 2-8 times the distance between the second protrusion and the support member.

5. The mold for preparing an acetabular cup according to claim 1, characterized in that: The distance between the second protrusion and the support member gradually decreases from the center to the periphery.

6. The mold for preparing an acetabular cup according to claim 1, characterized in that: A plurality of baffles are provided on the surface of the support member facing the second protrusion.

7. A method for preparing an acetabular cup, characterized in that: The following steps are involved: Passing a cooling liquid having a temperature of -10 to 20° C. into the base of the mold for preparing the acetabular cup according to any one of claims 1 to 6; After adding a slurry containing camphene as a solvent into a molding container, the molding container is placed on a base and frozen to obtain a blank; The acetabular cup can be obtained by drying and sintering the blank.

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