Synchronous pulley and 3D printer

Abstract

The utility model discloses a synchronous pulley and 3D printer, said synchronous pulley includes: main part, has first end and second end opposite to each other, the main part is provided with the through main body channel between first end and second end, from the first end to second end at least part of main body channel's cross-sectional area gradually increases, surrounds main body channel, and the first end and the second end of main body channel around the main body channel. A tooth-shaped structure meshed with a synchronous belt is arranged on the outer circumference of at least part of the main body part; the inner sleeve is provided with a head end and a tail end which are opposite to each other, a through inner sleeve channel is formed between the head end and the tail end of the inner sleeve, the main body part is arranged on the periphery of the inner sleeve in a sleeving manner through the main body channel, and the inner sleeve comprises a locking section comprising the head end and a sleeving section which is matched and connected with the main body channel in a sleeving manner; the locking structure is used for applying axial pressure to the first end of the main body part, so that the sleeving section of the inner sleeve abuts against the inner wall of the main body channel; the synchronous pulley can solve the problems that a traditional synchronous pulley is prone to dislocation and eccentric rotation and unreliable in fixation.

Description

Technical Field

[0001] This utility model relates to the field of transmission equipment, specifically to a synchronous belt pulley and a 3D printer. Background Technology

[0002] Synchronous pulleys are key components in synchronous belt drive systems. They mesh with the synchronous belt to achieve precise power transmission and motion control. Traditional synchronous pulleys are typically integrated units; when a component fails, the entire pulley needs to be replaced, increasing production costs. Furthermore, traditional synchronous pulleys are usually fixed to the motor shaft using locating screws, threaded couplings, or press-fit connections, which can easily lead to misalignment, eccentric rotation, unreliable fixing, or uneven weight distribution, affecting the pulley's motion accuracy. Utility Model Content

[0003] The present invention aims to solve the above-mentioned technical problems and provide a synchronous pulley that is reliably fixed after assembly with the motor shaft, does not rotate eccentrically or misalign, and has a uniform weight distribution.

[0004] In a first aspect, the present invention provides a synchronous belt pulley, comprising a main body having a first end and a second end, wherein a through main channel is formed between the first end and the second end, and the cross-sectional area of ​​at least a portion of the main channel increases from the first end to the second end; a toothed structure for meshing with a synchronous belt is provided around the main channel on the outer periphery of at least a portion of the main body; an inner sleeve having a first end and a second end, wherein a through inner sleeve channel is formed between the first end and the second end; the main body is fitted onto the outer periphery of the inner sleeve through the main channel; the inner sleeve includes a locking section including the first end and a sleeve section adapted to engage with the main channel; and a locking structure abutting against the first end of the main body and lockingly connected to the locking section of the inner sleeve passing through the main body, for applying axial pressure to the first end of the main body, thereby pressing the sleeve section of the inner sleeve against the inner wall of the main body forming the main channel.

[0005] In the preferred technical solution of the above-mentioned synchronous pulley, at least part of the main channel is a frustum-shaped channel or a truncated pyramid-shaped channel.

[0006] In the preferred embodiment of the above-mentioned synchronous pulley, the locking structure is a locking nut, and the outer periphery of the locking section of the inner sleeve has a thread that is compatible with the locking nut.

[0007] In the preferred embodiment of the above-mentioned synchronous pulley, from the first end to the second end, the first end of the main body has a radially contracting step, and the locking nut is threadedly locked with the inner sleeve locking section and abuts against the step.

[0008] In the preferred embodiment of the above-mentioned synchronous pulley, the main body includes a toothed segment with a toothed structure on its outer periphery, and a baffle with a second end connected to the toothed segment. The baffle has at least one limiting groove from the second end. The tail end of the inner sleeve is connected to at least one protrusion that extends radially outward and is adapted to the limiting groove, so that after the main body is fitted onto the outer periphery of the inner sleeve, the protrusion is embedded in the limiting groove.

[0009] In the preferred embodiment of the synchronous pulley described above, the baffle and the locking structure extend beyond the toothed section in the radial direction, forming a step with the toothed section, which is used to limit the synchronous belt when the synchronous pulley is working.

[0010] In the preferred embodiment of the above-mentioned synchronous pulley, the limiting groove is either sector-shaped or rectangular.

[0011] In the preferred embodiment of the above-mentioned synchronous pulley, the sleeve section includes multiple independent sleeve plates connected to the locking section, with gaps between each sleeve plate, and the locking section and the sleeve section forming an umbrella-shaped structure after being connected.

[0012] In a second aspect, the present invention also provides a 3D printer, which includes the aforementioned synchronous pulley.

[0013] The beneficial effects of this utility model are as follows: This application designs the synchronous pulley as a detachable main body, inner sleeve, and locking structure. In application, the inner sleeve is fitted onto the motor shaft, and the inner sleeve channel after assembly of the main body, inner sleeve, and locking structure is adapted to the motor shaft. By fitting the inner sleeve onto the main body and applying axial pressure to the main body using the locking structure, the main body moves further axially towards the tail end of the inner sleeve, thereby causing the inner wall of the main body channel to apply radial inward pressure to the inner sleeve, locking the main body and the inner sleeve together, and locking the inner sleeve and the motor shaft together. After the synchronous pulley and the motor shaft are assembled, they are reliably fixed, do not rotate eccentrically, and have a uniform weight distribution. Furthermore, the synchronous pulley can independently replace and upgrade its components, and it features convenient installation, high structural strength, and low production cost. Attached Figure Description

[0014] Figure 1 This is the main view of the present utility model. Figure 1 ;

[0015] Figure 2 This is the main view of the present utility model. Figure 2 ;

[0016] Figure 3 This is a cross-sectional view of the present invention;

[0017] Figure 4 Schematic diagram of the main body Figure 1;

[0018] Figure 5 Schematic diagram of the main body Figure 2 ;

[0019] Figure 6 Schematic diagram of the inner sleeve Figure 1 ;

[0020] Figure 7 Schematic diagram of the inner sleeve Figure 2 ;

[0021] Figure 8 Schematic diagram of the inner sleeve Figure 3 ;

[0022] In the figure: main body 1, first end 11, second end 12, main body channel 13, toothed section 14, toothed structure 141, step 15, baffle 16, limiting groove 161, inner sleeve 2, first end 21, tail end 22, inner sleeve channel 23, locking section 24, sleeve section 25, sleeve plate 251, protrusion 26, locking structure 3. Detailed Implementation

[0023] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0024] It should be noted that in the description of this utility model, terms such as "upper," "lower," "left," "right," "front," and "rear," which indicate direction or positional relationships, are based on the direction or positional relationships shown in the accompanying drawings. These are used merely for ease of description and do not indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0025] Furthermore, it should be noted that, in the description of this utility model, unless otherwise explicitly specified and limited, the terms "set," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0026] See Figures 1 to 8The synchronous belt pulley of this utility model includes: a main body 1 having a first end 11 and a second end 12, wherein a through main body channel 13 is formed between the first end 11 and the second end 12, and the cross-sectional area of ​​at least a portion of the main body channel 13 continuously increases from the first end 11 to the second end 12; and a toothed structure 141 for meshing with a synchronous belt is provided around the outer periphery of at least a portion of the main body 1 surrounding the main body channel 13; and an inner sleeve 2 having a first end 21 and a tail end 22, wherein the inner sleeve 2 has a toothed structure 141 for meshing with a synchronous belt from the first end 21 to the tail end 22. An inner sleeve channel 23 is provided between the ends 22. The main body 1 is sleeved on the outer periphery of the inner sleeve 2 through the main body channel 13. The inner sleeve 2 includes a locking section 24 including the first end 21 and a sleeve section 25 that is adapted to be connected to the main body channel 13. The locking structure 3 abuts against the first end 11 of the main body 1 and is locked to the locking section 24 of the inner sleeve 2 that passes through the main body 1. It is used to apply axial pressure to the first end 11 of the main body 1 so that the sleeve section 25 of the inner sleeve 2 abuts against the inner wall of the main body channel 13.

[0027] See Figures 1 to 5From the first end 11 to the second end 12 of the main body 1, a through main body channel 13 is provided inside the main body 1. The main body channel 13 is used to fit the outer periphery of the inner sleeve 2. From the first end 11 to the second end 12, the cross-sectional area of ​​the main body channel 13 of the main body 1 continuously increases. As an understanding, the continuous increase in cross-sectional area means that from the first end 11 to the second end 12, the opening of the cross-section of the main body channel 13 continuously expands outward. The increasing trend can be continuous and gradual or non-gradual, preferably gradual. The outer periphery of the main body 1 is provided with a toothed structure 141, which is used to interact with the synchronization belt in the 3D printer. For the meshing installation, the toothed structure 141 and the timing belt installation method refer to existing technologies and are not specifically limited here. From the first end 21 to the last end 22 of the inner sleeve 2, a through inner sleeve channel 23 is provided on the inner sleeve 2. The inner sleeve channel 23 is used to fit the motor shafts in the 3D printer, such as circular shafts and D-shaped shafts. It is only necessary that the motor shaft and the inner sleeve channel 23 are compatible after installation. For example, if the motor shaft is a circular shaft, the inner sleeve channel 23 surrounding the outer circumference of the motor shaft after installation will be a channel with a circular cross-section opening; if the motor shaft is a D-shaped shaft, the inner sleeve channel 23 surrounding the outer circumference of the motor shaft after installation will be a channel with a D-shaped cross-section opening. The inner sleeve 2 includes a locking section 24 containing the first end 21 and a main body channel with the main body 1. The 13-matched fitting section 25 is fitted with a locking section 24 whose cross-section is smaller than the opening at the first end 11 of the main body channel 13 so that the main body 1 can be smoothly fitted onto the fitting section 25. The locking structure 3 is detachably located at the first end 11 of the main body 1 and abuts against the first end 11. It is used to lock the inner sleeve 2 locking section 24, which passes through the main body channel 13 and is placed at the first end 11 of the main body 1. While locking the inner sleeve 2, the locking structure 3 can apply axial pressure to the first end 11 of the main body 1. During the locking process, it promotes the movement and slight movement of the main body 1 towards the tail end 22 of the inner sleeve 2, increases the friction between the fitting section 25 of the inner sleeve 2 and the main body channel 13 of the main body 1, and makes the main body 1 move towards the tail end 22 of the inner sleeve 2. The main body 1 exerts radial inward pressure on the inner sleeve 2. The inner sleeve 2, upon receiving this pressure, contracts radially inward, which in turn exerts radial inward pressure on the motor shaft fitted within the inner sleeve channel 23. This achieves locking of the main body 1 onto the inner sleeve 2 and locking of the inner sleeve 2 onto the motor shaft, further improving the stability of the connection between the two. It can be understood that the axial direction is the direction in which the main body channel 13 extends from the first end 11 to the second end 12 or from the second end 12 to the first end 11, or the direction of the length of the motor shaft within the inner sleeve channel 23. The radial direction is perpendicular to the axial direction. In this application, the main body 1 is made of rigid material. When the inner sleeve 2 receives a radial inward force, the inner sleeve 2 will contract radially inward.

[0028] Specifically, when installing the synchronous pulley of this application, firstly, the inner sleeve 2 is installed on the motor shaft, and then the main body 1 is fitted onto the inner sleeve 2. For example, the second end 12 of the main body 1 is inserted into the inner sleeve 2 from the first end 21 and moves towards the tail end 22, so that the locking section 24 of the inner sleeve 2 extends to the first end 11 of the main body 1. Subsequently, the locking section 24 of the inner sleeve 2 is locked using the locking structure 3, and the outer wall of the sleeve section 25 of the inner sleeve 2 abuts against the inner wall of the main body channel 13, thereby achieving the locking of the main body 1 and the inner sleeve 2, and the locking connection of the inner sleeve 2 and the motor shaft. The compatibility between the main channel 13 and the sleeve section 25, and the compatibility between the motor shaft and the inner sleeve channel 23, means that the inner sleeve 2 can be sleeved onto the motor shaft, and the main body 1 can be sleeved onto the sleeve section 25 of the inner sleeve 2. After the synchronous pulley is installed on the motor shaft and locked by the locking structure 24, at least a portion of the contact area between the inner wall of the main body 1 of the main channel 13 and the outer periphery of the sleeve section 25 is interference-fitted, preferably all of the contact area is interference-fitted. At least a portion of the contact area between the motor shaft and the inner sleeve channel 23 is interference-fitted, preferably all of the contact area is interference-fitted. The synchronous pulley and the motor shaft of this application are reliably fixed after assembly, do not rotate eccentrically, and have a uniform weight distribution. Compared with the traditional one-piece synchronous pulley, the modular synchronous pulley of this application has the advantage of independently replaceable and upgraded parts, convenient installation, high structural strength, low production cost, and since the inner sleeve 2 of the corresponding inner sleeve channel 23 shape can be replaced according to the shape of the motor shaft, this application can be compatible with various motor shaft types.

[0029] In one or more embodiments, at least a portion of the main channel 13 is a frustum-shaped channel or a truncated pyramid-shaped channel.

[0030] See Figure 3 At least a portion of the main channel 13 is either a frustum-shaped channel or a truncated pyramidal channel. It should be noted that at least a portion of the main channel 13 refers to a section of the main body 1 in the direction from the first end 11 to the second end 12. In this application, by setting the main channel 13 to a frustum-shaped or truncated pyramidal shape, the fitting segment 25 of the inner sleeve 2, which is fitted to the outside of the main channel 13, is adapted to the main channel 13. Therefore, the fitting segment 25 is also at least partially frustum-shaped or truncated pyramidal in its outer periphery. This allows the fitting segment 25 of the inner sleeve 2 to abut against the inner wall of the main channel 13, thereby restricting the relative movement between the inner sleeve 2 and the main body 1, achieving the fixing effect between the inner sleeve 2 and the main body 1, and further fixing the motor shaft.

[0031] For example, at least part of the socket section 25 is shaped like a frustum or a pyramid. As an implementable method, when the main channel 13 is shaped like a frustum, the inner sleeve 2 is also shaped like a frustum. After installation, the side edge of the inner sleeve 2 is in linear contact with the side edge on the inner wall of the main body 1 that forms the main channel 13.

[0032] In one or more embodiments, the locking structure 3 is a locking nut, and the outer periphery of the locking section 24 of the inner sleeve 2 has threads adapted to the locking nut.

[0033] See Figures 1 to 6 When the first end 21 of the inner sleeve 2 passes through the main channel 13 and extends to the first end 11 of the main body 1, the locking nut can be screwed onto the thread of the locking section 24 of the inner sleeve 2, so that the inner sleeve 2 is fixed on the main body 1. As the locking nut is screwed onto the thread of the locking section 24 of the inner sleeve 2 and the locking nut abuts against the main body 1, the main body 1 is subjected to axial pressure from the tightening contact of the locking nut. The main body 1 moves towards the tail end 22 of the inner sleeve 2, so that the inner wall of the main channel 13 and the outer wall of the sleeve section 25 of the inner sleeve 2 are further pressed together, ensuring the strength of the connection between the main body 1 and the inner sleeve 2 and improving the locking effect of the two. The further pressing of the main channel 13 against the outer wall of the sleeve section 25 further locks the motor shaft of the inner sleeve 2.

[0034] In one or more embodiments, from the first end 11 to the second end 12, the first end 11 of the main body 1 has a radially contracting step 15, and the locking nut is threadedly locked to the locking section 24 of the inner sleeve 2 and pressed against the step 15.

[0035] See Figures 3 to 5 After the locking nut is threadedly locked to the locking section 24 of the inner sleeve 2, the locking nut will fit the vertical part of the step 15, and the bottom end of the locking nut will press against the horizontal part of the step 15 of the first end 11 of the main body 1, thereby reducing the axial length of the synchronous pulley of this application and limiting the radial position of the main body 1.

[0036] In one or more embodiments, the main body 1 includes a toothed segment 14 with a toothed structure 141 on its outer periphery, and a baffle 16 connected to the toothed segment 14 including a second end 12. The baffle 16 has at least one limiting groove 161 opened from the second end 12. The tail end 22 of the inner sleeve 2 is connected to at least one protrusion 26 that extends radially outward and is adapted to the limiting groove 161, so that after the main body 1 is sleeved on the outer periphery of the inner sleeve 2, the protrusion 26 is embedded in the limiting groove 161.

[0037] See Figures 1 to 5The toothed segment 14 on the outer periphery of the main body 1 is used to install the timing belt. The main body 1 includes a baffle 16 with a second end 12. The baffle 16 is fixedly connected to the toothed segment 14 of the main body 1, for example, by integral molding. During operation, it rotates synchronously from the second end 12 toward the first end 11. The baffle 16 has at least a plurality of limiting grooves 161. Specifically, the number of limiting grooves 161 can be 1, 2, 3, 4, 5, 6, etc., without specific limitation. Preferably, they are evenly distributed in a circular array. The limiting grooves 161 can penetrate the baffle 16 radially, or they can not penetrate the baffle 16 radially, so that the limiting grooves 161 are blocked on the outer periphery. The tail end 22 of the inner sleeve 2 has one or more protrusions 26 extending radially outward. Here, the end of the sleeve segment away from the first end 21 is the tail end 22 of the inner sleeve 2. The protrusion 26 is block-shaped or a flat thick plate, etc., without specific limitation. After the protrusion 26 is connected to the sleeve segment 25, it will extend radially beyond the sleeve segment 25. The protrusion 26 will not block the inner channel 23. Here, it is preferred that the protrusion 26 and the tail end 22 are integrally formed and connected. When the inner sleeve 2 enters the main channel 13 of the main body 1 and is locked by the locking structure 3, the protrusion 26 that matches the limiting groove 161 can be embedded in the limiting groove 161 and limited by the limiting groove 161, thereby restricting the relative rotation of the main body 1 and the inner sleeve 2 in the circumferential direction, avoiding the relative rotation between the inner sleeve 2 and the main body 1 under external force, and improving the stability of the synchronous pulley of this application during operation.

[0038] It is understandable that there is no limit to the number of limiting grooves 161 and the number of protrusions 26. The number of limiting grooves 161 and protrusions 26 is greater than or equal to 2, but the two numbers do not have to be equal. The number of protrusions 26 can be less than the number of limiting grooves 161. The specific selection can be made according to the actual production needs. The protrusions 26 are connected to the tail end 22 and extend radially outward beyond the sleeve section 25. This can be understood as starting the connection from the end face of the tail end 22, or starting the connection from the outer edge of the tail end 22.

[0039] The shape of the limiting groove 161 is not specifically limited. In one or more embodiments, the limiting groove 161 is either fan-shaped or rectangular.

[0040] See Figure 3 , Figure 4 , Figure 5 For example, the limiting groove 161 at the second end 12 of the main body 1 has a fan-shaped structure, and the protrusion 26 at the tail end 22 of the inner sleeve 2 has a fan-shaped structure that matches the limiting groove 161. With this arrangement, the protrusion 26 can only enter the limiting groove 161 along the axial direction of the main body 1, thereby further fixing the relative position of the inner sleeve 2 and the main body 1.

[0041] In one or more embodiments, the baffle 16 and the locking structure 3 extend radially beyond the toothed section 14, forming a step with the toothed section 14, for limiting the timing belt when the timing pulley is working.

[0042] See Figure 4 The synchronous pulley of this application has a cross-section that is roughly "I" shaped. The radial lengths of the locking nut provided at the first end 11 of the main body 1 and the baffle 16 provided at the second end 12 are both greater than the radial length of the toothed section 14. This allows the synchronous belt to be limited by the baffle 16 and the locking nut after it is installed on the toothed section 14 of the main body 1, thus ensuring the stability of the connection between the synchronous belt and the synchronous pulley.

[0043] The surface roughness of the inner wall of the main channel 13 and / or the socket section 25 is not specifically limited. In one or more embodiments, the surface roughness of at least a portion of the inner wall of the main channel 13 and / or the socket section 25 is 0.8 μm to 3.2 μm.

[0044] By setting a higher roughness on the inner wall of the main channel 13 and the outer wall of the inner sleeve 2 connecting section 25, the friction between the inner wall of the main channel 13 and the outer wall of the connecting section 25 is increased. When the locking nut is tightened on the inner sleeve 2, the friction between the inner wall of the main channel 13 and the outer wall of the connecting section 25 can further press the inner sleeve 2 onto the main body 1.

[0045] In one or more embodiments, from the tail end 22 of the inner sleeve 2 toward the head end 21 of the inner sleeve 2, the sleeve section 25 includes a plurality of independent sleeve plates 251 connected to the locking section 24, with gaps between each sleeve plate 251, and the locking section 24 and the sleeve section 25 are connected to form an umbrella rib structure.

[0046] It is understandable that the inner sleeve channel 23 of the inner sleeve 2 is a channel for fitting the motor shaft. The motor shaft is in contact with the inner wall of the inner sleeve 2. The fitting plates 251 can be the same or different. For example, when the motor shaft is a round shaft, the fitting plates 251 can be the same. When the motor shaft is a D-shaped shaft or other shaped shaft, the radial end face shape of the fitting plates 251 can not be exactly the same. As long as the synchronous pulley is installed on the motor shaft, the inner sleeve channel 23 formed by the fitting plates 251 can be adapted to the motor shaft. For example, after fitting, an inner sleeve channel 23 that can be assembled with a round shaft motor shaft is formed, or an inner sleeve channel 23 that can be assembled with a D-shaped shaft motor shaft is formed.

[0047] See Figures 6 to 8From the tail end 22 toward the head end 21, the inner sleeve 2's connecting section 25 is composed of multiple, for example, six, independent connecting plates 251 connected to the locking section 24. Gaps exist between the connecting plates 251, giving the inner sleeve 2 an umbrella-like structure. It should be noted that the connecting plates 251, at the end furthest from the locking section 24 (the tail end 22), are connected to radially outwardly extending protrusions 26. These six protrusions 26 are independent and respectively embedded in the limiting grooves 161 of the main body 1's baffle 16, thereby restricting the relative rotation of the main body 1 and the inner sleeve 2 in the circumferential direction. Through the umbrella-like structure, the locking nut abuts against the main body 1, applying axial force. When the main body 1 moves toward the tail end 22 and feeds into the inner sleeve 2, forming an inward force, the connecting plates 251 of the inner sleeve 2 can more easily tighten and deform inward to lock the motor shaft.

[0048] It is understood that the socket plate 251 near the locking section 24 of the inner sleeve 2 may also include a portion of the thread that is compatible with the locking nut, so that when the locking nut locks the inner sleeve 2, it applies inward pressure to the socket plate 251 to lock the motor shaft.

[0049] In addition, this utility model also provides a 3D printer having the synchronous belt pulley in any of the above embodiments.

[0050] The above embodiments are only for illustrating the technical concept and features of this utility model. Their purpose is to enable those skilled in the art to understand the content of this utility model and implement it. They cannot be used to limit the protection scope of this utility model. All equivalent changes or modifications made in accordance with the spirit and essence of this utility model should be covered within the protection scope of this utility model.

Claims

1. A synchronous belt pulley, characterized in that, include: The main body has a first end and a second end, and a through main body channel is provided between the first end and the second end. The cross-sectional area of ​​at least a portion of the main body channel increases from the first end to the second end. Around the main body channel, at least a portion of the outer periphery of the main body is provided with a toothed structure for meshing with a timing belt. The inner sleeve has a front end and a rear end, and a through inner sleeve channel is provided between the front end and the rear end. The main body is sleeved on the outer periphery of the inner sleeve through the main body channel. The inner sleeve includes a locking section including the front end and a sleeve section that is adapted to be fitted with the main body channel. A locking structure is provided, which abuts against the first end of the main body and is locked to a locking section passing through the inner sleeve of the main body. The locking structure is used to apply axial pressure to the first end of the main body, so that the sleeve section of the inner sleeve abuts against the inner wall of the main body forming the main channel.

2. The synchronous pulley according to claim 1, characterized in that: At least part of the main channel is a frustum-shaped channel or a truncated pyramid-shaped channel.

3. The synchronous pulley according to claim 1, characterized in that: The locking structure is a locking nut, and the outer periphery of the locking section of the inner sleeve has a thread that is compatible with the locking nut.

4. The synchronous pulley according to claim 3, characterized in that: From the first end to the second end, the first end of the main body has a radially tapering step, and the locking nut is threadedly locked to the inner sleeve locking section and abuts against the step.

5. The synchronous pulley according to claim 1, characterized in that: The main body includes a toothed segment with a toothed structure on its outer periphery, and a baffle with a second end connected to the toothed segment. The baffle has at least one limiting groove from the second end. The tail end of the inner sleeve is connected to at least one protrusion that extends radially outward and is adapted to the limiting groove, so that after the main body is fitted onto the outer periphery of the inner sleeve, the protrusion is embedded in the limiting groove.

6. The synchronous pulley according to claim 5, characterized in that: The baffle and the locking structure extend radially beyond the toothed section, forming a step with the toothed section, which is used to limit the timing belt when the timing pulley is working.

7. The timing pulley according to claim 5, characterized in that: The limiting groove is either sector-shaped or rectangular.

8. The synchronous pulley according to claim 1 or 4, characterized in that: From the tail end of the inner sleeve toward the head end of the inner sleeve, the sleeve section includes multiple independent sleeve plates connected to the locking section, with gaps between each sleeve plate, and the locking section and the sleeve section are connected to form an umbrella-shaped structure.

9. A 3D printer, characterized in that: Includes the timing pulley according to any one of claims 1 to 8.

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