Rubber roller fixing installation structure for printer

Abstract

The utility model relates to thermal printer technical field, concretely relates to the rubber roll fixed mounting structure for printer, including shaft sleeve, rubber roll and support, be equipped with the baffle and elastic catch on the shaft sleeve, the rubber roll is stepless optical axis, and the support is equipped with the notched and the convex bundle. When assembling, the rubber roll is worn into the support, and the shaft sleeve is sleeved in the rubber roll end portion and rotates, makes the baffle insert the notched and realizes the circumferential limit, and the elastic catch resets after passing the convex bundle and forms the axial limit. The utility model need not the snap spring and special tool, and the bare hands can complete the assembly and dismounting, has the reliable structure, low in cost, the advantage that the process is simplified.

Description

Technical Field

[0001] This utility model relates to the field of thermal printer technology, and more specifically to a rubber roller fixing and mounting structure for a printer. Background Technology

[0002] In the manufacturing process of office and industrial equipment such as thermal printers, rubber rollers are key transmission and pressing components, and their assembly structure directly affects the overall production efficiency, reliability, and manufacturing cost. Traditionally, rubber roller bushings are fixed using a snap ring structure, which limits axial displacement of the bushing by installing a metal snap ring at the shaft end.

[0003] However, this method has many drawbacks in actual production: on the one hand, the installation of the snap ring requires special tools, which is cumbersome and requires high skills from the assemblers; on the other hand, the snap ring is prone to deformation, detachment or even breakage during assembly or use, which can cause the bushing to loosen, affect the stability of the rubber roller, and thus reduce the reliability of the product.

[0004] Furthermore, in the context of large-scale automated production, complex assembly steps not only extend working hours but also increase labor and maintenance costs, making it difficult to meet the current manufacturing needs of the thermal printer industry for high efficiency, low cost, and high consistency.

[0005] Therefore, there is an urgent need for a simple, easy-to-assemble, and reliable rubber roller bushing installation solution to overcome the problems of complex processes, insufficient reliability, and high costs in the existing technology. Utility Model Content

[0006] This invention addresses the shortcomings of existing methods for fixing rubber roller bushings in office equipment such as thermal printers using snap rings. These shortcomings include complex assembly processes, reliance on specialized tools, increased costs due to numerous parts, and the risk of snap ring failure leading to bushing loosening or detachment. The invention provides a rubber roller fixing and installation structure that eliminates the need for snap rings and specialized tools, allowing for manual assembly and reliable positioning. This structure integrates a stop and elastic hook on the bushing body, along with a limiting groove and protrusion structure on the bracket, achieving dual circumferential and axial limiting of the bushing. This simplifies the assembly process while improving structural stability and manufacturing economy.

[0007] This utility model provides a fixed installation structure for a printer's rubber roller, including a bushing, a rubber roller, and a bracket. The bushing is a hollow cylindrical component with an inner diameter that matches the outer diameter of the rubber roller's end, used to fit onto the end of the rubber roller. An axially extending stop and circumferentially distributed elastic hooks are integrally formed on the outer circumferential surface of the bushing. The rubber roller is a smooth, thread-free, and stepless shaft structure, cylindrical in shape with a smooth, continuous outer surface, used to pass through a support hole inside the bracket. The bracket is a fixed component supporting the rotational movement of the rubber roller, with a support hole for the rubber roller to pass through. A limiting structure is provided at the end region of the support hole. The limiting structure includes a slot or gap for the stop to be inserted, and a convex structure located on one side of the slot. The convex structure protrudes from the bracket surface towards the bushing fitting direction, with its top profile being an arc-shaped transition surface and its bottom smoothly connected to the bracket body.

[0008] Further, the stop block is a rectangular or trapezoidal block that protrudes radially outward from the outer circumference of the bushing. Its height extends axially along the bushing, its width extends circumferentially along the bushing, and its length is not less than 1 / 8 and not more than 1 / 4 of the outer circumference of the bushing. The front end face of the stop block is a plane perpendicular to the bushing axis, and the rear end face is a plane parallel to the front end face or a slightly angled slope. The elastic hook is formed by partially cutting and bending the outer circumference of the bushing, and includes a connecting part, a cantilever part, and a locking part. The connecting part is integrally connected to the outer circumference of the bushing. The cantilever extends axially from the connecting part along the bushing and bends away from the center of the bushing. The snap-fit ​​part is located at the end of the cantilever, and its free end is provided with a guide slope facing the bushing assembly direction, and a stop plane is provided on the side away from the assembly direction. The number of elastic snap hooks is one or more, and they are evenly or non-uniformly distributed along the circumference of the bushing. Their outer contour size in the natural state is larger than the spatial size of the corresponding assembly path on the bracket, so that during the bushing rotation assembly process, the elastic snap hooks need to undergo elastic deformation to pass over the convex structure on the bracket.

[0009] The slot on the bracket is an open slot formed at the edge of the end of the support hole. Its depth direction extends through or partially through the thickness direction of the bracket, its width matches the circumferential width of the stop block, and its depth is not less than the axial height of the stop block. One side edge of the slot is adjacent to a convex structure, which is located downstream of the slot in the circumferential direction. The convex structure's protrusion height is 0.3mm to 1.2mm higher than the bracket surface, and its top curvature radius is 0.5mm to 2.0mm, to ensure that the elastic hook can slide smoothly and achieve elastic reset during rotation. The axial position of the convex structure corresponds to the axial position of the elastic hook on the bushing, so that when the bushing rotates to a predetermined angle, the elastic hook is exactly above the convex structure and completes the locking action.

[0010] The assembly process specifically includes the following steps: S1: Pass the rubber roller through the support hole on the bracket along the axial direction, so that both ends of the rubber roller extend out of the bracket on both sides respectively. The rubber roller and the support hole are clearance fit or slightly interference fit to ensure that the rubber roller can rotate freely around its own axis. S2: Take the bushing, align its inner hole with one end of the rubber roller, and push it in axially until the bushing is completely fitted onto the end of the rubber roller. At this time, the stop block and elastic hook on the bushing are located outside the bracket and do not contact the bracket limiting structure. S3: Rotate the bushing in the predetermined rotation direction (clockwise or counterclockwise) so that the stop block moves circumferentially with the bushing and enters the slot on the bracket. The front end face of the stop block abuts against the inner side wall of the slot, thereby restricting the circumferential rotation of the bushing relative to the bracket. S4: As the bushing continues to rotate, the guide slope of the elastic hook first contacts the top of the protrusion on the bracket. Since the height of the protrusion is greater than the natural extension height of the elastic hook, the elastic hook is compressed and undergoes inward elastic deformation, the cantilever bends, and the locking part rises upward. When the elastic hook passes the highest point of the protrusion, under the action of the material's elastic restoring force, the cantilever rebounds, causing the stop plane of the locking part to fall on the bracket surface on the back side of the protrusion, forming an axial limit on the bushing and preventing it from coming out along the axial direction of the rubber roller.

[0011] Specifically, the bushing is integrally injection molded from engineering plastic, with materials such as polyoxymethylene (POM), polyamide (PA), or polycarbonate (PC). Its elastic modulus is sufficient to withstand a pressing force of at least 0.5N to 3.0N during assembly without permanent plastic deformation. The cantilever length of the elastic hook is 2.0mm to 6.0mm, and the thickness is 0.8mm to 1.5mm, to balance elastic deformation capacity and structural strength. The angle between the stop and the elastic hook in the circumferential direction of the bushing is 30° to 90°, ensuring that during rotational assembly, the stop first completes circumferential positioning, and then the elastic hook completes axial locking, avoiding interference between the two.

[0012] Furthermore, the slot on the bracket and the convex structure are located in the same axial plane, and the entrance edge of the slot is chamfered or rounded, with a chamfer angle of 30° to 60° and a rounded radius of 0.3mm to 1.0mm, to reduce the frictional resistance when the stop block is inserted; the circumferential width of the convex structure is not less than the circumferential width of the elastic hook engagement part, ensuring that the engagement part completely covers the back side area of ​​the convex structure, preventing the hook from failing due to local stress concentration; the outer diameter tolerance of the rubber roller end is controlled within ±0.02mm, and the inner hole tolerance of the bushing is controlled within +0.03mm / -0.01mm, to ensure tight fitting and smooth rotation.

[0013] The angle between the guide slope of the elastic hook and the axis of the bushing is 15° to 45°. This angle design allows the normal component of the force applied by the convex bulge to the hook to be effectively converted into a radial component that causes the hook to deform inward during the rotational assembly process, while reducing circumferential resistance. The stop plane is parallel to the surface of the bracket and has an area of ​​not less than 0.5 mm² to provide sufficient reaction force to resist the axial vibration or impact load that the bushing may be subjected to during equipment operation.

[0014] Furthermore, when it is necessary to disassemble the bushing, the operator can pinch the bushing with their fingers and press the elastic hook inward to make the cantilever part elastically deform again, and the locking part disengages from the back of the convex bulge. Then, the bushing is rotated in the opposite direction to make the stop block exit the groove, and the bushing can be pulled out from the end of the rubber roller. The entire disassembly and assembly process does not require the use of any tools such as screwdrivers or snap ring pliers, and can be completed by hand, which significantly improves maintenance efficiency.

[0015] The beneficial effects of this utility model are as follows: This invention achieves dual limiting of the bushing by integrating a stop and an elastic hook onto the bushing body, forming a mechanical interlock with the slot and protrusion structure on the bracket: the stop, after being inserted into the slot, restricts the circumferential rotation of the bushing relative to the bracket, preventing slippage of the bushing due to torque transmission during printing; the elastic hook, after passing the protrusion, resets, its stop plane abutting against the back of the protrusion, restricting the bushing's outward movement along the roller axis, preventing the bushing from falling off due to equipment vibration or transportation impact. This structure eliminates the need for auxiliary fasteners such as independent snap rings, screws, or adhesives in traditional solutions, reducing the types and number of parts, lowering material management complexity, and reducing assembly time; simultaneously, all limiting features are achieved through the geometry of the structural components themselves, requiring no additional processing or assembly steps, making it suitable for mass automated production.

[0016] Furthermore, because the rubber roller adopts a stepless, threadless optical shaft structure, its processing is simplified to a single external cylindrical grinding or turning step, eliminating the need for end milling, tapping, or knurling, significantly reducing machining costs and scrap rates. The mating structure of the bushing and bracket uses geometric features achievable through conventional injection molding or stamping, requiring no high-precision secondary processing, further reducing manufacturing costs. In space-constrained and cost-sensitive office equipment such as thermal printers, this structure can effectively enhance product competitiveness without sacrificing functional reliability.

[0017] In summary, the simplified installation structure for the rubber roller bushing provided by this utility model, through the synergistic action of the stop block and elastic hook on the bushing, and in conjunction with the groove and protrusion on the bracket, constructs a mechanical connection solution that requires no external fasteners, allows for quick manual assembly and disassembly, provides precise positioning, and exhibits excellent vibration resistance. The structural design of this solution fully considers key factors such as material elasticity, geometric tolerances, assembly path guidance, and ease of disassembly, ensuring high feasibility and engineering practicality in actual production and use. Attached Figure Description

[0018] Figure 1 This is a three-dimensional structural schematic diagram of the present invention; Figure 2 This is a cross-sectional front view of the stop block in this utility model; Figure 3 This is a cross-sectional front view of the elastic buckle in this utility model; Figure 4 This is a three-dimensional structural diagram of the bushing of this utility model; Figure 5 This is a three-dimensional structural diagram of the bracket in this utility model; In the diagram, 1 is the bushing; 2 is the stop block; 3 is the elastic hook; 4 is the rubber roller; 5 is the bracket; 6 is the convex bulge; and 7 is the groove. Detailed Implementation

[0019] The specific embodiments of this utility model will be further described in detail below with reference to the accompanying drawings.

[0020] Refer to the instruction manual appendix Figure 1-5 This utility model provides a rubber roller fixing and mounting structure for a printer. Its core lies in the use of a stop 2 and an elastic hook 3 integrated on the bushing 1, combined with a groove 7 and a protrusion 6 on the bracket 5, to achieve an assembly structure that achieves axial and circumferential dual-limiting without the need for retaining springs or special tools. In this embodiment, this structure is applied to the rubber roller assembly in a thermal printer to support and fix the rubber roller 4 within the bracket 5, ensuring stable rotation during printing without axial detachment or circumferential slippage.

[0021] The rubber roller 4 is a cylindrical shaft structure with no steps, threads, knurling, or other machining features at both ends. Its outer surface is smooth and continuous, and its outer diameter is controlled within a tolerance of ±0.02mm to ensure a good fit with the inner hole of the bushing 1. The rubber roller 4 passes through the support hole in the middle of the bracket 5. This support hole is a through hole with an inner diameter slightly larger than the outer diameter of the rubber roller 4, forming a clearance fit or a slight interference fit. This allows the rubber roller 4 to rotate freely around its own axis within the bracket 5 while maintaining good coaxiality and stability.

[0022] The bracket 5 is a metal stamping or injection-molded plastic part. It has a structure at the end of the support hole for limiting the bushing 1, including a slot 7 and a protrusion 6. The slot 7 is an opening at the edge of the support hole, extending through the thickness of the bracket 5 in the depth direction. Its width matches the circumferential width of the stop 2, and its depth is not less than the axial height of the stop 2, ensuring that the stop 2 can be fully inserted and abut against the inner wall of the slot 7. The entrance edge of the slot 7 has a chamfered angle of 45° and a chamfer radius of 0.5mm to reduce frictional resistance when the stop 2 is inserted. The protrusion 6 is located on the circumferential downstream side of the slot 7, with a protrusion height of 0.8mm, a top curvature radius of 1.2mm, and an arc-shaped transition surface. Its bottom is smoothly connected to the body of the bracket 5. The axial position of the protrusion 6 corresponds to the axial position of the elastic hook 3 on the bushing 1. The circumferential width is 1.5mm, which is slightly larger than the circumferential width of the snap-fit ​​part of the elastic hook 3, so as to ensure that the snap-fit ​​part completely covers the back side area of ​​the protrusion 6 and prevents local stress concentration from causing the hook to fail.

[0023] The bushing 1 is a hollow cylindrical component, integrally injection molded from polyoxymethylene (POM) material, possessing good rigidity and elastic recovery capabilities. The inner diameter of the bushing 1 is matched with the outer diameter of the end of the rubber roller 4, with tolerances controlled within +0.03mm / -0.01mm, ensuring a tight fit without affecting the smooth rotation of the rubber roller 4. A stop block 2 and an elastic hook 3 are integrally formed on the outer circumference of the bushing 1. The stop block 2 is a rectangular block protruding radially outward from the outer circumference of the bushing 1, with its height extending along the axial direction of the bushing 1, and its length being 1 / 6 of the outer circumference of the bushing 1. The front end face is a plane perpendicular to the axis of the bushing 1, and the rear end face is a slightly angled slope, facilitating smooth entry into the groove 7 during rotation.

[0024] The elastic hook 3 is formed by partially cutting and bending the outer circumferential surface of the bushing 1, and includes a connecting part, a cantilever part, and a locking part. The connecting part is integrally connected to the outer circumferential surface of the bushing 1; the cantilever part extends 2.5 mm axially from the connecting part along the bushing 1, has a thickness of 1.0 mm, and bends away from the center of the bushing 1; the locking part is located at the end of the cantilever part, and its free end has a guide slope facing the assembly direction of the bushing 1. The angle between the guide slope and the axis of the bushing 1 is 30°, and a stop plane with an area of ​​0.6 mm² is provided on the side away from the assembly direction, which is parallel to the surface of the bracket 5. There is one elastic hook 3, which is located 60° downstream of the stop block 2 in this embodiment, to ensure that during the rotation assembly process, the stop block 2 first completes circumferential positioning, and then the elastic hook 3 completes axial locking, avoiding interference between the two.

[0025] The bushing 1 is fitted onto the end of the rubber roller 4 and is rotated and positioned relative to the bracket 5. At this time, the stop block 2 is fully inserted into the groove 7, and its front end face is tightly abutted against the inner side wall of the groove 7, restricting the circumferential rotation of the bushing 1 relative to the bracket 5; the stop plane of the snap-fit ​​part of the elastic hook 3 falls on the surface of the bracket 5 on the back side of the protrusion 6, forming an axial limit on the bushing 1, preventing it from coming out axially along the rubber roller 4.

[0026] The specific assembly process is as follows: S1: Pass the rubber roller 4 axially through the support hole on the bracket 5, so that both ends of the rubber roller 4 extend out of both sides of the bracket 5. The rubber roller 4 and the support hole are in clearance fit to ensure that the rubber roller 4 can rotate freely around its own axis; S2: Take the bushing 1, align its inner hole with one end of the rubber roller 4, and push it in axially until the bushing 1 is completely fitted onto the end of the rubber roller 4. At this time, the stop 2 and the elastic hook 3 on the bushing 1 are both located outside the bracket 5 and are not in contact with the limiting structure of the bracket 5; S3: Rotate the bushing 1 clockwise so that the stop 2 moves circumferentially with the bushing 1 and enters the groove 7 on the bracket 5. The front end face of the stop 2 abuts against the inner wall of the groove 7, thereby limiting the movement of the roller 4. S4: As the bushing 1 continues to rotate clockwise, the guide slope of the elastic hook 3 first contacts the top of the protrusion 6 on the bracket 5. Since the height of the protrusion 6 (0.8mm) is greater than the natural extension height of the elastic hook 3 (about 0.6mm), the elastic hook 3 is compressed and undergoes inward elastic deformation, the cantilever bends, and the locking part rises upward. When the elastic hook 3 passes the highest point of the protrusion 6, under the action of the elastic restoring force of the POM material, the cantilever rebounds, so that the stop plane of the locking part falls on the surface of the bracket 5 on the back side of the protrusion 6, forming an axial limit on the bushing 1 and preventing it from coming out axially along the rubber roller 4.

[0027] During equipment operation, the rubber roller 4 bears the pressure from the print head and the torque generated by paper friction. After the stop block 2 is inserted into the slot 7, it can effectively transmit torque and prevent the bushing 1 from slipping circumferentially relative to the bracket 5; the stop plane of the elastic hook 3 abuts against the back side of the protrusion 6, which can resist the axial vibration or transportation impact load that may be generated during equipment operation and prevent the bushing 1 from falling off. Tests showed that under the action of axial tensile force of 0.5N to 3.0N, the bushing 1 did not loosen or fall off, indicating that the structure has good vibration resistance and connection reliability.

[0028] When the bushing 1 needs to be disassembled for maintenance or replacement, the operator can pinch the outer circumference of the bushing 1 with their thumb and forefinger, and press the cantilever of the elastic hook 3 with the thumb of the other hand to cause it to elastically deform inward again, disengaging the locking part from the back side of the protrusion 6; then rotate the bushing 1 in the opposite direction (counterclockwise) to make the stop 2 exit the slot 7; finally, pull the bushing 1 out from the end of the rubber roller 4 axially. The entire disassembly and assembly process does not require the use of any tools such as screwdrivers or snap ring pliers, and can be completed by hand, significantly improving maintenance efficiency.

[0029] In this embodiment, the mating structure of the bushing 1, the rubber roller 4, and the bracket 5 are all geometric features that can be achieved through conventional injection molding or stamping processes, requiring no high-precision secondary machining. The rubber roller 4 adopts a stepless optical shaft structure, eliminating the end milling, tapping, or knurling processes in traditional solutions, reducing machining costs by approximately 30%. The limiting structure of the bushing 1 and the bracket 5 is formed in one piece using a mold, eliminating the need for additional fasteners during assembly, reducing the number of parts by two (traditionally requiring a retaining ring + retaining ring groove), and significantly reducing material management complexity and assembly time. In the mass production of thermal printers, a single machine can save approximately 8 seconds of assembly time, and an annual output of 1 million units can save hundreds of thousands of yuan in labor costs.

[0030] In summary, this utility model, through the synergistic action of the stop block 2 and the elastic hook 3 on the bushing 1, and in conjunction with the slot 7 and protrusion 6 on the bracket 5, constructs a mechanical connection solution that requires no external fasteners, allows for quick manual assembly and disassembly, provides precise positioning, and exhibits excellent vibration resistance. The structural design of this solution fully considers key factors such as material elasticity, geometric tolerances, assembly path guidance, and ease of disassembly, ensuring high feasibility and engineering practicality in actual production and use. All technical features can be achieved through conventional manufacturing processes, making it suitable for applications sensitive to space constraints and cost, such as office automation equipment, receipt printers, and label printers.

Claims

1. A roller fixing and mounting structure for a printer, comprising a bushing (1), a roller (4), and a bracket (5); characterized in that: The bushing (1) is a hollow cylindrical component with an inner diameter that matches the outer diameter of the end of the rubber roller (4) and is used to fit onto the end of the rubber roller (4). The bushing (1) has an axially extending stop (2) and a circumferentially distributed elastic hook (3) integrally formed on its outer circumferential surface. The rubber roller (4) is a smooth shaft structure without steps or threads at both ends. It is cylindrical in shape and has a smooth and continuous outer surface. It is used to pass through the support hole inside the bracket (5). The bracket (5) has a support hole for the rubber roller (4) to pass through, and a limiting structure is provided at the end area of ​​the support hole. The limiting structure includes a slot (7) for the stop (2) to be inserted and a protrusion (6) located on one side of the slot (7). The protrusion (6) protrudes from the surface of the bracket (5) in the direction of the bushing (1) assembly. Its top profile is an arc transition surface, and its bottom is smoothly connected to the body of the bracket (5).

2. The roller fixing and mounting structure for a printer as described in claim 1, characterized in that: The stop block (2) is a rectangular or trapezoidal block that protrudes radially outward from the outer periphery of the bushing (1). Its height extends along the axial direction of the bushing (1), and its width extends along the circumference of the bushing (1). Its length is not less than 1 / 8 and not more than 1 / 4 of the outer periphery of the bushing (1). The front end face of the stop block (2) is a plane perpendicular to the axis of the bushing (1), and the rear end face is a plane parallel to the front end face or a slightly inclined plane.

3. The roller fixing and mounting structure for a printer as described in claim 2, characterized in that: The elastic hook (3) is formed by partially cutting and bending the outer peripheral surface of the bushing (1), and includes a connecting part, a cantilever part and a snap-fit ​​part; the connecting part is integrally connected to the outer peripheral surface of the bushing (1), the cantilever part extends from the connecting part along the axial direction of the bushing (1) and bends away from the center of the bushing (1), the snap-fit ​​part is located at the end of the cantilever part, its free end is provided with a guide slope facing the assembly direction of the bushing (1), and a stop plane is provided on the side away from the assembly direction.

4. The roller fixing and mounting structure for a printer as described in claim 1, characterized in that: The slot (7) is an opening slot opened at the edge of the support hole of the bracket (5). Its depth direction extends through or partially through the thickness direction of the bracket (5). Its width matches the circumferential width of the stop (2), and its depth is not less than the axial height of the stop (2). One side edge of the slot (7) is adjacent to the convex bulge (6).

5. The roller fixing and mounting structure for a printer as described in claim 4, characterized in that: The protrusion height of the convex bulge (6) is 0.3 mm to 1.2 mm higher than the surface of the bracket (5), and the top curvature radius is 0.5 mm to 2.0 mm; the axial position of the convex bulge (6) corresponds to the axial position of the elastic hook (3) on the bushing (1).

6. The roller fixing and mounting structure for a printer as described in claim 3, characterized in that: The cantilever length of the elastic hook (3) is 2.0 mm to 6.0 mm, and the thickness is 0.8 mm to 1.5 mm; the angle between the guide slope and the axis of the bushing (1) is 15° to 45°, and the stop plane is parallel to the surface of the bracket (5) with an area of ​​not less than 0.5 mm².

7. The roller fixing and mounting structure for a printer as described in claim 1, characterized in that: The included angle between the stop (2) and the elastic hook (3) in the circumferential direction of the bushing (1) is 30° to 90°; the inlet edge of the slot (7) is provided with a chamfer or rounded corner, the chamfer angle is 30° to 60°, and the rounded corner radius is 0.3mm to 1.0mm.

8. The roller fixing and mounting structure for a printer as described in claim 1, characterized in that: The outer diameter tolerance of the end of the rubber roller (4) is ±0.02mm, and the inner hole tolerance of the bushing (1) is +0.03mm / -0.01mm; the circumferential width of the convex bulge (6) is not less than the circumferential width of the snap-fit ​​part of the elastic hook (3).

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