A type of expandable trial mold

Abstract

This invention provides an expandable trial mold, including a handle; a transmission mechanism, the proximal end of which is connected to the handle; and an expansion assembly, the distal end of which is connected to the transmission mechanism. The expansion assembly includes a main body and a first expansion member movably mounted on the main body. When the handle is rotated, the transmission mechanism applies force to the first expansion member, causing the first expansion member to move closer to or further away from the main body. The expandable trial mold provided by this invention allows the length of the expansion assembly to be adjusted by rotating the handle. Therefore, only one trial mold is needed during surgery, allowing the surgeon to accurately simulate the implantation of an object. This eliminates the need for frequent insertion and removal of other trial molds during surgery, avoiding damage to surrounding tissues, reducing the risk of surgical complications, and improving the success rate of the surgery.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, and in particular to an expandable prototype. Background Technology

[0002] Interbody fusion is a surgical procedure primarily used to treat lumbar spine disorders such as herniated discs, spinal stenosis, and spondylolisthesis. The procedure involves creating a minimally invasive access point to the affected area, or performing open surgery to expose the diseased disc and vertebral body. The affected area is then cleared, and with minimal damage to surrounding tissues, a fusion cage is implanted between adjacent vertebral segments using assistive instruments. It fuses with the adjacent vertebral bodies to form a unified structure, stabilizing the spine.

[0003] In the planning of interbody fusion surgery, the trial molds function as measuring instruments during the procedure, typically used in orthopedic surgery to measure dimensions such as diameter and depth. For traditional fixed-size interbody fusion cages, different sized trial molds must be inserted, compared, and removed sequentially from smallest to largest before implantation until a correct fit is achieved for the patient. This process must be evaluated under fluoroscopic imaging throughout to determine the appropriate length and position of the final implant. This significantly increases surgical time. Furthermore, the frequent insertion and removal of different sized trial molds during surgery to determine implant dimensions can cause tissue damage and increase surgical risks. Summary of the Invention

[0004] The purpose of this invention is to provide an expandable trial mold with adjustable size, thereby reducing surgical time and risks.

[0005] To achieve the above objectives, in a first aspect, the present invention provides an expandable trial mold comprising: handle; The transmission mechanism is connected to the handle at its proximal end; A spreading assembly is connected to the distal end of the transmission mechanism. The spreading assembly includes a main body and a first spreading member movably disposed on the main body. When the handle is rotated, the force is applied to the first spreading member through the transmission mechanism, so that the first spreading member and the main body member move closer to each other or further apart. In some embodiments, the spreading assembly further includes a first connecting member located within the first spreading member and fixedly connected to the first spreading member, the first connecting member being throttle-connected to the transmission mechanism.

[0006] In some embodiments, the transmission mechanism includes a transmission shaft, a first support shaft, a first gear, a worm, and a first worm wheel; The first support shaft is rotatably disposed within the first expansion member; Both the first worm gear and the first gear are sleeved on the first support shaft and fixedly connected to the first support shaft; The worm meshes with the first worm wheel, and the proximal end of the worm is fixedly connected to the distal end of the drive shaft; The proximal end of the drive shaft is fixedly connected to the distal end of the handle; The first connector has a first rack structure on one side wall, which meshes with the first gear.

[0007] In some embodiments, the transmission mechanism further includes a first bearing sleeved on the end of the first support shaft, the first bearing being fixedly connected to the main body.

[0008] In some embodiments, the number of the first bearing, the first connector, and the first gear are all two; The two first bearings are respectively sleeved on both ends of the first support shaft and are fixedly connected to the main body; The two first gears are spaced apart and sleeved on the first support shaft; Two of the first connecting members are spaced apart within the first supporting member and respectively mesh with one of the corresponding first gears.

[0009] In some embodiments, the transmission mechanism further includes at least one washer slidably fitted onto the end of the worm gear; When the worm rotates, the washer remains stationary.

[0010] In some embodiments, the lead angle of the worm is set to be smaller than its equivalent friction angle, and the transmission efficiency of the worm is less than 50%.

[0011] In some embodiments, the spreading assembly further includes a second spreading member and a second connecting member; The second support member is movably disposed on the main body member and is disposed opposite to the first support member; The second connecting member is located inside the second supporting member and is fixedly connected to the second supporting member; the second connecting member is drive-connected to the transmission mechanism. When the handle is rotated, the force is applied to the first and second supporting members through the transmission mechanism, so that the first and second supporting members move closer to or further away from each other.

[0012] In some embodiments, the transmission mechanism further includes a second support shaft, a second gear, and a second worm gear; The second support shaft is rotatably disposed within the second expansion member and is disposed opposite to the first support shaft; The second worm gear and the second gear are both sleeved on the second support shaft and fixedly connected to the second support shaft; The distal end of the worm meshes with the second worm wheel, and the proximal end of the worm is fixedly connected to the distal end of the drive shaft; The second connector has a second rack structure on one side wall, which meshes with the second gear.

[0013] In some embodiments, the transmission mechanism further includes a second bearing sleeved on the end of the second support shaft, the second bearing being fixedly connected to the main body.

[0014] In some embodiments, the number of the second bearing, the second connecting member, and the second gear are all two; The two second bearings are respectively sleeved on both ends of the second support shaft and are fixedly connected to the main body; The two second gears are spaced apart and fitted onto the second support shaft; Two second connecting members are spaced apart within the second supporting member and respectively mesh with a corresponding second gear.

[0015] In some embodiments, a transmission channel is provided on the main body; The drive shaft is a double universal coupling, with the distal end of the drive shaft movably passing through the transmission channel and fixedly connected to the proximal end of the worm gear.

[0016] In some embodiments, the first support member has a first notch on one side wall near the transmission channel, and the second support member has a second notch on one side wall near the transmission channel. When the first support member and the second support member approach each other, the diameter of the area formed by the cooperation of the first notch and the second notch is larger than the diameter of the transmission channel.

[0017] In some embodiments, a distance mark is provided on a portion of the sidewall of the first connector and the second connector; The first support member, the second support member, and the main body member are provided with a visible window corresponding to the distance mark.

[0018] In some embodiments, the handle includes a grip, a linkage, and a rotating part; The gripping part has a hollow structure; The drive shaft is movably inserted into the grip, and the proximal end of the drive shaft is fixedly connected to the distal end of the connecting rod. The rotating part is a ratchet handle, and the distal end of the ratchet handle is fixedly connected to the proximal end of the connecting rod.

[0019] The advantages of the expandable trial mold provided by this invention are as follows: 1. The expansion component is connected to the handle through a transmission mechanism. The length of the expansion component can be adjusted by rotating the handle. Therefore, only one of these trial molds is needed during the operation to allow the doctor to accurately simulate the situation inside the implanted object. There is no need to frequently insert and remove other trial molds during the operation, which avoids damage to surrounding tissues, reduces the risk of surgical complications, and improves the success rate of the operation.

[0020] 2. The handle, transmission mechanism and spreading component work closely together, and the handle has a self-locking function, which makes the spreading component have a good spreading effect, improves surgical efficiency, shortens surgical time, and reduces patient pain and surgical risks.

[0021] 3. The expansion component has a viewing window, which allows for observation of the adjusted size of the expansion component during the operation, improving the accuracy of the operation. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of a stretchable test mold provided in an embodiment of the present invention; Figure 2 An exploded view of the components and transmission mechanism provided in the embodiments of the present invention; Figure 3 A partial structural schematic diagram of the transmission mechanism provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of the structure after the washer is installed on the worm gear according to an embodiment of the present invention; Figure 5 A schematic diagram of a stretchable trial mold according to another embodiment of the present invention; Figure 6 A schematic diagram of the structure of the transmission mechanism after it is connected to the first connecting member and the second connecting member according to an embodiment of the present invention; Figure 7 This is a schematic diagram showing the first and second support members being arranged opposite to each other in an embodiment of the present invention. Figure 8 A schematic diagram of the structure of the transmission mechanism after it is connected to the first connecting member and the second connecting member, according to another embodiment of the present invention; Figure 9 This is a schematic diagram of the main component of an embodiment provided by the present invention; Figure 10 This is a schematic diagram of the structure of a test mold that can be opened when the gripping part fully accommodates the drive shaft, according to an embodiment of the present invention.

[0023] Figure label: Handle 1, grip part 11, connecting rod 12, rotating part 13, transmission mechanism 2, transmission shaft 201, first support shaft 202, first gear 203, worm 204, first worm wheel 205, first bearing 206, washer 207, second support shaft 208, second gear 209, second worm wheel 210, second bearing 211, spreading assembly 3, main body 31, cylindrical structure 311, transmission channel 312, first spreading member 32, first notch 321, first connecting member 33, first rack structure 331, second spreading member 34, second notch 341, second connecting member 35, second rack structure 351, viewing window 36. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention. Unless otherwise defined, the technical or scientific terms used herein should have the ordinary meaning understood by those skilled in the art to which this invention pertains. The terms "comprising" and similar expressions used herein mean that the element or object preceding the word covers the element or object listed after the word and its equivalents, without excluding other elements or objects. Unless otherwise specified, the term "connection" as used herein can refer to a direct connection or an indirect connection, i.e., a connection through an intermediate object.

[0025] Furthermore, it should be understood that the orientations or positional relationships indicated by terms such as "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer" in this document are based on the orientations or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. The terms "first" and "second" in this document are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the invention, unless otherwise stated, "a plurality of" means two or more.

[0026] In this text, the term "distal" refers to the end that is farther from the operator and closer to the patient; the term "proximal" refers to the end that is closer to the operator and farther from the patient.

[0027] To address the problems existing in the prior art, embodiments of the present invention provide an expandable trial mold, as shown in the reference. Figure 1and Figure 2 As shown, the expandable mold includes a handle 1, a transmission mechanism 2, and an expansion assembly 3. The proximal end of the transmission mechanism 2 is fixedly connected to the distal end of the handle 1, and the distal end of the transmission mechanism 2 is connected to the expansion assembly 3. The expansion assembly 3 includes a main body 31 and a first expansion member 32 movably mounted on the main body 31. Both the main body 31 and the first expansion member 32 are sleeve-type structures. The first expansion member 32 is sleeved on one end of the main body 31, and the end face of the first expansion member 32 away from the main body 31 abuts against the surface of the cone. When the handle 1 rotates, the transmission mechanism 2 applies force to the first expansion member 32, causing the first expansion member 32 to move closer to or further away from the main body 31.

[0028] In this embodiment, the outer sidewall of the main body 31 is provided with a convex sliding groove along its extending direction, and the inner sidewall of the first supporting member 32 is provided with a concave sliding groove along its extending direction. The concave sliding groove is adapted to the convex sliding groove. The mutual cooperation between the concave sliding groove and the convex sliding groove ensures the stability of the first supporting member 32 during the sliding process.

[0029] In addition, it is understood that the expandable test mold provided in this embodiment can adjust the length of the expandable component 3 by rotating the handle 1. Therefore, only one test mold is needed during the operation to allow the doctor to accurately simulate the situation inside the implanted object. There is no need to frequently insert and remove other test molds during the operation, which avoids damage to surrounding tissues, reduces the risk of surgical complications, and improves the success rate of the operation.

[0030] refer to Figure 1 and Figure 2 As shown, in some embodiments, the spreading component 3 further includes a first connecting member 33 located inside the first spreading member 32 and fixedly connected to the first spreading member 32. The first connecting member 33 is connected to the transmission mechanism 2. When the handle 1 drives the transmission mechanism 2 to rotate, the transmission mechanism 2 can apply a rotational force to the first connecting member 33. After being subjected to force, the first connecting member 33 can drive the first spreading member 32 to move along its extension direction.

[0031] Specifically, in combination Figure 3 , 4As shown, the transmission mechanism 2 includes a transmission shaft 201, a first support shaft 202, a first gear 203, a worm 204, and a first worm wheel 205. The first support shaft 202 is rotatably disposed within the first spreading member 32. The first worm wheel 205 and the first gear 203 are both sleeved on the first support shaft 202 and fixedly connected to it. Therefore, the first support shaft 202, the first worm wheel 205, and the first gear 203 can rotate synchronously. The helical teeth structure near the distal end of the worm 204 meshes with the first worm wheel 205. The proximal end of the worm 204 is fixedly connected to the distal end of the transmission shaft 201, for example, by welding or a fixing pin. The proximal end of the transmission shaft 201 is fixedly connected to the distal end of the handle 1. In addition, a first rack structure 331 is provided on one side wall of the first connector 33. The extension direction of the first rack structure 331 is the same as the extension direction of the first support member 32, and the first rack structure 331 meshes with the first gear 203.

[0032] In this embodiment, when the handle 1 drives the transmission shaft 201 to rotate, the transmission shaft 201 drives the worm gear 204 to rotate synchronously. The rotation of the worm gear 204 drives the first worm wheel 205 to rotate, which in turn drives the first support shaft 202 and the first gear 203 to rotate. Since the first gear 203 meshes with the first rack structure 331, it drives the first connecting member 33 and the first spreading member 32 to move. It can be understood that due to the close cooperation between the handle 1, the transmission mechanism 2, and the spreading assembly 3, the spreadable trial mold structure in this embodiment is compact, has a small overall size, is easy to operate and use, improves surgical efficiency, shortens surgical time, and reduces patient pain and surgical risks.

[0033] refer to Figures 1 to 3 As shown, in some embodiments, the transmission mechanism 2 further includes a first bearing 206 sleeved on the end of the first support shaft 202, and the first bearing 206 is fixedly connected to the main body 31.

[0034] In this embodiment, the inner sidewall of the main body 31 may be provided with a mounting structure groove for mounting the first bearing 206. By providing the first bearing 206 at the end of the first support shaft 202 and fixing the first bearing 206 to the main body 31, the stability of the first support shaft 202 during rotation is ensured, and torsional failure of the main body 31 after being subjected to force is also avoided.

[0035] It should be noted that in this embodiment, there are two of each of the first bearing 206, the first connecting member 33, and the first gear 203. By setting two of each of these components, the stability of the first supporting member 32 during movement is further ensured. Specifically, the first worm gear 205 is sleeved on the middle part of the first support shaft 202 and is fixedly connected to it. The two first bearings 206 are symmetrically sleeved on both ends of the first support shaft 202 and are fixedly connected to the main body 31 to further ensure the smoothness of the first support shaft 202 during rotation and also to further ensure the stability of the main body 31. The two first gears 203 are sleeved on the first support shaft 202 at intervals, and are symmetrically arranged on both sides of the first worm gear 205. The two first connecting members 33 are spaced apart inside the first supporting member 32 and mesh with a corresponding first gear 203.

[0036] In some embodiments, the number of the first bearing 206, the first connector 33, and the first gear 203 is one. Compared with this embodiment, the stability of the expandable mold provided in this embodiment is somewhat worse.

[0037] refer to Figure 1 , Figure 2 and Figure 4 As shown, in some embodiments, the transmission mechanism 2 further includes at least one washer 207, which is slidably sleeved on the end of the worm 204, and remains stationary when the worm 204 rotates.

[0038] In this embodiment, two washers 207 are used to respectively fit onto both ends of the worm 204 to improve the stability of the worm 204 during rotation. It is understood that, since the washers 207 are slidable, when the worm 204 rotates, the relative sliding between the washers 207 and the worm 204 counteracts its axial movement, ensuring that the position of the washers 207 remains unchanged.

[0039] In some embodiments, the lead angle of the worm 204 is set to be less than its equivalent friction angle, and the transmission efficiency of the worm 204 is set to be less than 50%.

[0040] In this embodiment, the reverse self-locking performance of the worm 204 can be achieved by setting the lead angle of the worm 204 to be smaller than its equivalent friction angle. Furthermore, to further improve the self-locking performance, the transmission efficiency of the worm 204 is set to be less than 50%.

[0041] In some embodiments, in order to further improve the self-locking performance of the worm gear 204, the transmission ratio i of the worm gear 204 can be designed to be in the range of 15 to 50.

[0042] refer to Figure 5 , Figure 6 and Figure 7 As shown, in some embodiments, the spreading assembly 3 further includes a second spreading member 34 and a second connecting member 35. The second spreading member 34 is movably disposed on the main body 31 and is disposed opposite to the first spreading member 32. The second connecting member 35 is located inside the second spreading member 34 and is fixedly connected to the second spreading member 34. The second connecting member 35 and the first connecting member 33 are respectively located on both sides of the first gear 203. The second connecting member 35 is drively connected to the transmission mechanism 2. When the handle 1 is rotated, the transmission mechanism 2 applies force to the first spreading member 32 and the second spreading member 34, causing the first spreading member 32 and the second spreading member 34 to move closer to or further away from each other.

[0043] In this embodiment, the structure of the second supporting member 34 is the same as that of the first supporting member 32. The inner sidewall of the second supporting member 34 is also provided with a concave groove along its extension direction. The concave groove on the second supporting member 34 matches the convex groove on the main body 31 to ensure the stability of the second supporting member 34 during sliding. It should be noted that by adding the second supporting member 34, bidirectional opening of the mold is achieved, increasing the adjustable range of the mold and further improving its applicability.

[0044] Furthermore, the transmission mechanism 2 also includes a second support shaft 208, a second gear 209, and a second worm gear 210, for transmitting power to the second spreading member 34. Specifically, the second support shaft 208 is rotatably disposed within the second spreading member 34 and is disposed opposite to the first support shaft 202. The second worm gear 210 and the second gear 209 are both sleeved on the second support shaft 208 and fixedly connected to the second support shaft 208, with the second worm gear 210 corresponding to the first worm gear 205 and the second gear 209 corresponding to the first gear 203. The distal end of the worm 204 is located between the second worm gear 210 and the first worm gear 205, and its two side walls mesh with the first worm gear 205 and the second worm gear 210, respectively. The proximal end of the worm 204 is fixedly connected to the distal end of the transmission shaft 201. A second rack structure 351 is provided on one side wall of the second connecting member 35, and the second rack structure 351 meshes with the second gear 209.

[0045] In this embodiment, when the handle 1 is rotated, the transmission mechanism 2 can simultaneously drive the first opening member 32 and the second opening member 34 to move in opposite directions, thereby realizing the opening and retraction of the opening component 3.

[0046] In some embodiments, the transmission mechanism 2 further includes a second bearing 211 sleeved on the end of the second support shaft 208, the second bearing 211 being symmetrically arranged with the first bearing 206, and the second bearing 211 being fixedly connected to the main body 31.

[0047] In this embodiment, the stability of the second support shaft 208 during rotation is ensured by providing the second bearing 211 on the second support shaft 208.

[0048] refer to Figure 6 and Figure 8 As shown, in some embodiments, there are two of each of the second bearing 211, the second connecting member 35, and the second gear 209. The second worm gear 210 is sleeved on the middle portion of the second support shaft 208 and fixedly connected to it. Two second bearings 211 are symmetrically sleeved on both ends of the second support shaft 208 and fixedly connected to the main body 31 to further ensure the smoothness of the second support shaft 208 during rotation and also to further ensure the stability of the main body 31. Two second gears 209 are spaced apart on the second support shaft 208, and are symmetrically arranged on both sides of the second worm gear 210. Two second connecting members 35 are spaced apart within the second spreading member 34 and mesh with a corresponding second gear 209.

[0049] In this embodiment, by setting the number of the second bearing 211, the second connecting member 35 and the second gear 209 to two, the stability of the second spreading member 34 during movement is further ensured.

[0050] refer to Figures 5 to 9 As shown, in some embodiments, a transmission channel 312 is provided on the main body 31. Specifically, the main body 31 has a protruding cylindrical structure 311, and the transmission channel 312 is formed on the cylindrical structure 311, connecting the main body 31. The transmission shaft 201 is a double universal coupling, and the distal end of the transmission shaft 201 movably passes through the transmission channel 312 and is fixedly connected to the proximal end of the worm gear 204.

[0051] In this embodiment, since the drive shaft 201 is a double universal coupling, when the handle 1, the double universal coupling, and the spreading assembly 3 have an angle, this angle difference can be compensated, so that the double universal coupling can achieve continuous power transmission while maintaining a relative positional relationship.

[0052] Furthermore, the first supporting member 32 has a first notch 321 on one side wall near the transmission channel 312, and the second supporting member 34 has a second notch 341 on one side wall near the transmission channel 312. When the first supporting member 32 and the second supporting member 34 approach each other, the diameter of the area formed by the first notch 321 and the second notch 341 is larger than the diameter of the transmission channel 312.

[0053] It is understandable that, since the transmission channel 312 is formed on the cylindrical structure 311, in order to prevent the first supporting member 32 and the second supporting member 34 from being affected by the cylindrical structure 311 when they come together, the first supporting member 32 is provided with a first notch 321 near one side wall of the transmission channel 312, and the second supporting member 34 is provided with a second notch 341 near one side wall of the transmission channel 312. The diameter of the area where the first notch 321 and the second notch 341 mate can be adapted to the cylindrical structure 311. With this configuration, when the first supporting member 32 and the second supporting member 34 come together and close, it can also prevent the internal parts from accidentally falling out when the trial mold is placed and removed, thus improving the safety of the operation.

[0054] In some embodiments, a portion of the sidewalls of the first connector 33 and the second connector 35 are provided with scale distance markings. The first support member 32, the second support member 34, and the main body member 31 are provided with viewing windows 36 corresponding to the scale distance markings.

[0055] In this embodiment, medical staff can directly read the moving distance of the first support member 32 and the second support member 34 through the viewing window 36 during the operation, which facilitates quick and accurate measurement during the operation.

[0056] In some embodiments, the handle 1 includes a gripping portion 11, a connecting rod 12, and a rotating portion 13. The gripping portion 11 has a hollow structure, and a drive shaft 201 is movably inserted within the gripping portion 11. The proximal end of the drive shaft 201 is fixedly connected to the distal end of the connecting rod 12. The rotating portion 13 is a ratchet handle, and the distal end of the ratchet handle is fixedly connected to the proximal end of the connecting rod 12.

[0057] In this embodiment, the gripping part 11 serves a gripping function. The gripping part 11 is sleeved on the transmission shaft 201, and its surface is designed with concave and convex features to conform to human hand gripping habits. The distal end of the gripping part 11 has a hexagonal circumferential arc, which prevents slippage when in contact with the spreading component 3. The hollow structure of the gripping part 11 is a hexagonal deep hole, which can completely accommodate the transmission shaft 201. When the gripping part 11 completely accommodates the transmission shaft 201, it can be considered as an integral connecting rod, such as... Figure 10 As shown. When the gripping part 11 is pushed back until the drive shaft 201 is fully exposed, since the drive shaft 201 is a double universal coupling, the spreading assembly 3 can move and spread out within a certain taper range along with the cone body, as shown. Figure 5 As shown, this effectively reduces the surgical incision area.

[0058] Additionally, it should be noted that the ratchet handle in this embodiment is a common ratchet mechanism, mainly composed of a ratchet, pawl, spring, stop plate, and handle 1, etc. The specific combination and connection method will not be described in detail here. When the ratchet handle rotates, the pawl engages with the tooth groove of the ratchet under the action of the spring, forming a temporary locking structure to prevent the ratchet handle from rotating on its own when no force is applied, thus giving the ratchet handle a self-locking function.

[0059] The above description is merely a specific implementation of the embodiments of this application, but the protection scope of the embodiments of this application is not limited thereto. Any changes or substitutions within the technical scope disclosed in the embodiments of this application should be covered within the protection scope of the embodiments of this application. Therefore, the protection scope of the embodiments of this application should be determined by the protection scope of the claims.

Claims

1. A stretchable trial mold, characterized in that, include: handle; The transmission mechanism is connected to the handle at its proximal end; A spreading assembly is connected to the distal end of the transmission mechanism. The spreading assembly includes a main body and a first spreading member movably disposed on the main body. When the handle is rotated, the force is applied to the first spreading member through the transmission mechanism, so that the first spreading member and the main body member move closer to each other or further apart. The expansion assembly further includes a first connecting member located inside the first expansion member and fixedly connected to the first expansion member, and the first connecting member is throttle-connected to the transmission mechanism. The transmission mechanism includes a transmission shaft, a first support shaft, a first gear, a worm, and a first worm wheel; The first support shaft is rotatably disposed within the first expansion member; Both the first worm gear and the first gear are sleeved on the first support shaft and fixedly connected to the first support shaft; The worm meshes with the first worm wheel, and the proximal end of the worm is fixedly connected to the distal end of the drive shaft; The proximal end of the drive shaft is fixedly connected to the distal end of the handle; The first connector has a first rack structure on one side wall, and the first rack structure meshes with the first gear; The lead angle of the worm gear is set to be less than its equivalent friction angle, and the transmission efficiency of the worm gear is less than 50%.

2. The expandable trial mold according to claim 1, characterized in that, The transmission mechanism further includes a first bearing sleeved on the end of the first support shaft, and the first bearing is fixedly connected to the main body.

3. The expandable trial mold according to claim 2, characterized in that, The number of the first bearing, the first connecting member, and the first gear are all two; The two first bearings are respectively sleeved on both ends of the first support shaft and are fixedly connected to the main body; The two first gears are spaced apart and sleeved on the first support shaft; Two of the first connecting members are spaced apart within the first supporting member and respectively mesh with one of the corresponding first gears.

4. The expandable trial mold according to claim 1, characterized in that, The transmission mechanism further includes at least one washer, which is slidably sleeved on the end of the worm gear; When the worm rotates, the washer remains stationary.

5. The expandable mold according to any one of claims 1 to 4, characterized in that, The expansion assembly further includes a second expansion member and a second connecting member; The second support member is movably disposed on the main body member and is disposed opposite to the first support member; The second connecting member is located inside the second supporting member and is fixedly connected to the second supporting member; the second connecting member is drive-connected to the transmission mechanism. When the handle is rotated, the force is applied to the first and second supporting members through the transmission mechanism, so that the first and second supporting members move closer to or further away from each other.

6. The expandable trial mold according to claim 5, characterized in that, The transmission mechanism also includes a second support shaft, a second gear, and a second worm gear; The second support shaft is rotatably disposed within the second expansion member and is disposed opposite to the first support shaft; The second worm gear and the second gear are both sleeved on the second support shaft and fixedly connected to the second support shaft; The distal end of the worm meshes with the second worm wheel, and the proximal end of the worm is fixedly connected to the distal end of the drive shaft; The second connector has a second rack structure on one side wall, which meshes with the second gear.

7. The expandable trial mold according to claim 6, characterized in that, The transmission mechanism further includes a second bearing sleeved on the end of the second support shaft, and the second bearing is fixedly connected to the main body.

8. The expandable trial mold according to claim 7, characterized in that, The number of the second bearing, the second connecting member, and the second gear are all two; The two second bearings are respectively sleeved on both ends of the second support shaft and are fixedly connected to the main body; The two second gears are spaced apart and fitted onto the second support shaft; Two second connecting members are spaced apart within the second supporting member and respectively mesh with a corresponding second gear.

9. The expandable trial mold according to claim 1, characterized in that, The main body is provided with a transmission channel; The drive shaft is a double universal coupling, with the distal end of the drive shaft movably passing through the transmission channel and fixedly connected to the proximal end of the worm gear.

10. The expandable trial mold according to claim 9, characterized in that, The first support member has a first notch on one side wall near the transmission channel, and the support assembly also includes a second support member, which has a second notch on one side wall near the transmission channel. When the first support member and the second support member approach each other, the diameter of the area formed by the first notch and the second notch is larger than the diameter of the transmission channel, and they close and surround the transmission channel.

11. The expandable trial mold according to claim 5, characterized in that, Distance markings are provided on part of the sidewalls of the first connector and the second connector; The first support member, the second support member, and the main body member are provided with a visible window corresponding to the distance mark.

12. The expandable trial mold according to claim 1, characterized in that, The handle includes a grip, a linkage, and a rotating part; The gripping part has a hollow structure; The drive shaft is movably inserted into the grip, and the proximal end of the drive shaft is fixedly connected to the distal end of the connecting rod. The rotating part is a ratchet handle, and the distal end of the ratchet handle is fixedly connected to the proximal end of the connecting rod.

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