A steel plate circular sawing machine power transmission system and a steel plate circular sawing machine comprising the same

Abstract

The application discloses a steel plate circular saw machine power transmission system, which comprises a motor, a gear box, a main shaft box, a main shaft and a cutter saw blade, and a first-stage worm transmission and a second-stage helical gear transmission are arranged in the gear box. The first-stage worm transmission is used for large reduction ratio speed reduction and torque increase, and the distance from the center of the output helical gear of the second-stage helical gear transmission to the lower bottom wall of the gear box is 90 mm, so that the 360 mm diameter saw blade can cut 100 mm thick steel plate. A side gap adjustable mechanism acting on the second-stage helical gear transmission is further arranged in the gear box and used for reducing sawing vibration and impact. The application significantly improves the cutting thickness capacity under the condition of fixed saw blade diameter, and has compact structure and stable transmission.

Description

Technical Field

[0001] This invention relates to CNC machine tools, specifically to the field of metal cutting equipment technology, and particularly to a power transmission system for a steel plate circular saw and a steel plate circular saw comprising the same. Background Technology

[0002] Circular saws are commonly used in metal cutting and processing, and are widely used for cutting and slitting steel plates and other profiles. With the increasing demands for processing efficiency and precision in the machinery manufacturing industry, high-speed cold-cut circular saws are gradually replacing traditional band saws and bow saws as the mainstream in the market due to their advantages such as good cutting quality, no need for secondary processing, energy saving and environmental protection.

[0003] In the design of steel plate circular saws, the power transmission system is the core component that determines the overall performance of the machine. In existing technologies, common transmission schemes mainly include the following: One approach is to use multi-stage helical gear reduction transmission. Its advantages are smooth transmission and high load-bearing capacity. However, in order to obtain a large reduction ratio, it is often necessary to set up multi-stage gear pairs, which results in a longer axial dimension of the gearbox and a less compact structure. Moreover, it is difficult to meet the dual requirements of large reduction ratio and large center distance by relying solely on helical gear transmission.

[0004] Secondly, a worm gear drive is used to achieve a large single-stage reduction. This solution can achieve a large reduction ratio and torque output with a smaller structural space, as illustrated in patent CN2693389Y: A circular saw blade holder and its saw blade tilting transmission mechanism, which uses a transmission structure in which a worm gear meshes with a sector worm wheel. However, because the tooth tip circle diameter of the worm wheel is relatively large, the bottom wall of the gearbox is relatively close to the worktable surface. When the saw blade diameter is fixed, the cutting depth is limited, making it difficult to meet the sawing requirements of thick steel plates.

[0005] Furthermore, in existing circular saw gear transmission systems, the meshing backlash between gear pairs is a significant factor causing sawing vibration and noise. Especially in systems combining worm gear and helical gear transmissions, the reverse impact load of the worm gear itself means that if backlash exists in the secondary helical gear transmission, it will significantly exacerbate saw blade vibration, affecting sawing quality and blade life. Regarding the gear backlash problem, some scholars have conducted relevant research. Patent CN114378363A, "Adaptive Backlash Elimination Gearbox and Circular Saw," eliminates gear meshing backlash by using an adaptive backlash elimination component and a helical tooth angle-pressing buffer component to generate a reverse force. Additionally, there are technical solutions using electromagnetic brakes to eliminate transmission backlash through braking torque. However, most of these backlash elimination technologies are designed for conventional gearboxes. In circular saw power systems using a combination of worm gear and helical gear transmissions, a solution that specifically integrates a backlash adjustment mechanism into the secondary helical gear transmission to complement the primary worm gear transmission structure and simultaneously address the problem of limited cutting thickness has not yet been reported.

[0006] On the other hand, patent CN107470708A, a high-speed cold-cutting circular saw for steel plates, uses a threaded drive feeding and infeeding structure, but does not address the specific layout optimization of the internal transmission system of the gearbox. Patent JPH03281303A, a control device that automatically stops sawing based on workpiece thickness to prevent saw blade overload, also fails to address the problem of limited cutting thickness from the perspective of transmission system structural design.

[0007] Therefore, how to achieve sawing of thicker steel plates with a reasonable transmission system layout under the premise of fixed saw blade diameter, while ensuring smooth transmission and compact structure, and effectively suppressing vibration caused by reverse impact of worm gear transmission, is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0008] The purpose of this invention is to overcome the defects in the prior art and provide a power transmission system for a steel plate circular saw, which aims to increase the maximum cutting thickness under a fixed saw blade diameter, while reducing sawing vibration through side clearance adjustment.

[0009] To achieve the above objectives, the technical solution of this invention is to design a power transmission system for a steel plate circular saw, comprising a motor, a gearbox, a spindle box, a spindle, a saw blade, and a crossbeam. The motor is connected to the gearbox, the gearbox is connected to the spindle box, the spindle box is inverted and mounted on the guide rail of the crossbeam, and the saw blade is connected to the spindle. The invention is characterized by: The gearbox includes a primary transmission mechanism and a secondary transmission mechanism. The primary transmission mechanism is a worm gear transmission mechanism; the secondary transmission mechanism is a helical gear transmission mechanism, which is coaxially arranged with the worm wheel of the primary transmission mechanism and is used to receive the power of the primary transmission mechanism and drive the main shaft to rotate. The vertical distance from the center of the output helical gear of the secondary transmission mechanism to the bottom wall of the gearbox is configured to be 90mm. Furthermore, the gearbox is equipped with a backlash adjustment mechanism, which acts on the helical gear pair of the secondary transmission mechanism to adjust the gear meshing backlash to reduce vibration and impact during the sawing process. 90mm is the distance from the output shaft axis to the lower mounting surface of the gearbox; this value is the result of comprehensive optimization to ensure gear strength, lubrication space, and cutting depth.

[0010] The primary transmission mechanism employs a worm gear drive to reduce the high-speed input of the motor (1500 r / min) to the low-speed output of 65 r / min required for processing, while significantly increasing the torque required for sawing (2500 N·m). The secondary transmission mechanism uses a helical gear drive, which is coaxially arranged with the worm wheel of the primary transmission mechanism. This helical gear drive receives power from the primary transmission mechanism and drives the spindle to rotate. Based on this two-stage transmission layout, this invention creatively configures the vertical distance from the center of the output helical gear of the secondary transmission mechanism to the bottom wall of the gearbox to be 90 mm. This parameter selection has significant structural implications: because the worm wheel in the primary worm gear drive has a large tip circle diameter, if only the primary worm gear drive is used for direct output, the bottom wall of the gearbox will inevitably be relatively close to the worktable, thus limiting the depth to which the saw blade can cut into the steel plate. However, by adding a secondary helical gear drive, and with the tip circle diameter of the secondary driven helical gear being significantly smaller than that of the worm wheel, the bottom wall of the gearbox can be further away from the worktable compared to the solution using only a primary worm gear drive. Calculations and verifications have shown that with this 90mm center distance configuration, and in conjunction with a 360mm diameter saw blade, it is possible to reliably cut steel plates up to 100mm thick, breaking through the conventional cutting thickness limitations of saw blades of the same diameter.

[0011] Furthermore, to overcome the problem of significant reverse impact inherent in worm gear drives, this invention also includes a backlash adjustment mechanism within the gearbox. This mechanism acts on the helical gear pair of the secondary transmission mechanism to adjust the gear meshing backlash, thereby reducing vibration and impact during the sawing process. By eliminating or reducing the tooth backlash of the secondary helical gear transmission, vibration transmission caused by impact loads is effectively suppressed, resulting in a smoother sawing process.

[0012] A further technical solution is that the backlash adjustable mechanism includes a split-type driving helical gear in the secondary transmission mechanism. The driving helical gear is coaxially assembled from a thick gear and a thin gear. The end face of the thick gear has an integrally formed protrusion for mounting the thin gear. The backlash adjustable mechanism also includes four sets of adjustment components. Each set of adjustment components includes a round pin, a semi-circular pin, and an adjusting spring that is fixedly connected to the round pin and the semi-circular pin at both ends. The thin gear has four elongated holes. The round pin passes through the semi-circular hole at the edge of the elongated hole and is inserted into the thick gear. The semi-circular pin abuts against the elongated hole. Another edge semicircular hole, the radius of the round pin and the semicircular pin are adapted to the radius of the semicircular hole of the oblong hole. The side clearance adjustable mechanism also includes an eccentric shaft, which includes a stepped cylinder and a hexagonal head integrally formed with the end of the stepped cylinder. The eccentric shaft passes through the thin gear and is inserted into the thick gear. The thin gear is provided with a through hole adapted to it, and the thick gear is provided with a blind hole adapted to the eccentric shaft. The stepped cylinder has two sections. The section closer to the hexagonal head is inserted into the blind hole on the thick gear, and the section closer to the hexagonal head passes through the thin gear. An annular cover plate is installed on the end face of the thin gear to block the oblong hole.

[0013] A further technical solution is that the transmission ratio of the primary transmission mechanism is 1500:65, and the output torque reaches 2500 N.m; the diameter of the saw blade is 360 mm.

[0014] The present invention also provides a technical solution for a steel plate circular saw, including the power transmission system of the steel plate circular saw, and further including a feeding mechanism, a discharging mechanism, a base and a worktable. After the steel plate to be processed is transported to the sawing position on the worktable by the feeding mechanism, the power transmission system drives the saw blade to complete the sawing process.

[0015] The advantages and beneficial effects of this invention are as follows: The system employs a two-stage layout combining a primary worm gear drive and a secondary helical gear drive, achieving both a large reduction ratio and a compact end-output structure. With a fixed saw blade diameter of 360mm, it enables a maximum cutting thickness of 100mm, significantly improving processing capabilities compared to a system using only a worm gear drive.

[0016] By configuring the output center distance of the two-stage helical gear transmission to 90mm, the clearance space of the bottom wall of the gearbox is optimized while ensuring gear strength. The structure is ingenious and the space utilization rate is high.

[0017] By adding a backlash adjustable mechanism to the two-stage helical gear transmission, the large reverse impact of the worm gear transmission is effectively addressed, reducing sawing vibration and noise, and extending the service life of the saw blade.

[0018] Compared to gearboxes that simply use multi-stage helical gear transmission, this solution requires fewer gear sets, has a more compact overall structure, and saves installation space. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of a steel plate circular saw including a power transmission system for a steel plate circular saw according to Embodiment 1 of the present invention; Figure 2 yes Figure 1 A diagram from another perspective; Figure 3 yes Figure 1 A schematic diagram from another perspective; Figure 4 yes Figure 3 A schematic diagram of the left view after being rotated 90° counterclockwise; Figure 5 yes Figure 1 A schematic diagram showing another perspective after the gearbox housing has been removed; Figure 6 yes Figure 5 A partially enlarged schematic diagram of the worm gear and its surrounding area; Figure 7 yes Figure 5A schematic diagram showing another perspective after removing the spindle box; Figure 8 yes Figure 7 A partially enlarged schematic diagram of the worm gear and its surrounding area; Figure 9 This is a schematic diagram of Embodiment 2 of the present invention; Figure 10 yes Figure 9 A magnified view of a portion of the driving helical gear in its vicinity; Figure 11 yes Figure 10 A magnified view of the area near the thin gear after the cover plate has been removed; Figure 12 yes Figure 11 A magnified view of the spring and its surrounding area after the thin gear has been removed; Figure 13 yes Figure 9 Another schematic diagram; Figure 14 yes Figure 13 A magnified schematic diagram of the central eccentric shaft and its vicinity; Figure 15 This is a schematic diagram of Embodiment 3 of the present invention; Figure 16 yes Figure 15 A schematic diagram after the gearbox housing has been removed; Figure 17 yes Figure 15 Perspective view of the gearbox.

[0020] In the diagram: 1. Steel plate; 2. Feeding mechanism; 3. Worm gear; 4. Worm wheel; 5. Driving helical gear; 6. Driven helical gear; 7. Cutting saw blade; 8. Output shaft; 9. Main shaft; 10. Motor housing; 11. Gearbox; 12. Main shaft housing; 13. Crossbeam; 14. Guide rail; 15. Slider; 16. Cover plate; 17. Thick gear; 18. Thin gear; 19. Protrusion; 20. Round pin; 21. Semi-circular pin; 22. Spring; 23. Oblong hole; 24. Eccentric shaft; 25. Hexagonal head; 401. Oil slinger; 1101. Lower bottom wall; 1102. Shallow oil pool; 1103. Spiral oil guide groove; 111. Oil collection box; 1111. Filter screen; 112. Oil pipe; 113. Oil injector; 1104. Heat dissipation fins. Detailed Implementation

[0021] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and examples. The following examples are only used to more clearly illustrate the technical solutions of the present invention and should not be construed as limiting the scope of protection of the present invention.

[0022] Example 1: As Figures 1 to 8As shown, this invention is a power transmission system for a steel plate circular saw, mainly comprising a motor, gearbox, spindle box, spindle, saw blade, crossbeam, base, loading mechanism, and unloading mechanism. The motor is housed in a motor housing 10 and connected to a gearbox 11. The gearbox is connected to a spindle box 12. The spindle box 12 is inverted and slidably mounted on the guide rail 14 of the crossbeam 13. The rear wall of the motor housing 10 is slidably mounted on the guide rail of the crossbeam via a slider 15. The saw blade 7 is connected to the spindle 9 of the spindle box. The diameter of the saw blade is 360mm. The saw blade cuts the steel plate. The core component is a worm gear drive within the gearbox, which reduces the motor speed from 1500r / min to the required processing speed of 65r / min and increases the required sawing torque to 2500N.m. The secondary transmission is a helical gear transmission. Due to the limitation of the first-stage reduction in the thickness of the steel plate that the saw blade can cut, it cannot meet the requirement of cutting steel plates with a thickness of 100mm (because the tooth tip circle diameter of the worm wheel in the worm gear transmission mechanism is relatively large. If only the first-stage worm gear transmission is used, the bottom wall of the gearbox will inevitably be closer to the worktable, thus limiting the thickness of the steel plate that the saw blade can cut. However, after the worm gear transmission is connected to the second-stage helical gear transmission, the tooth tip circle diameter of the driven gear of the second-stage helical gear is smaller. Therefore, the bottom wall of the gearbox can be further away from the worktable compared to the bottom wall of the gearbox using only the first-stage worm gear transmission). It is required that the distance from the center of the output helical gear of the second-stage reduction to the bottom surface of the gearbox must be guaranteed to be 90mm. An adjustable backlash mechanism is added to the second-stage transmission to reduce sawing vibration and impact. This makes the designed power transmission system of the steel plate circular saw smooth, compact, and able to saw steel plates with a thickness of 100mm when the saw blade diameter is fixed at 360mm.

[0023] Operation process: The sawing process includes the steel plate 1 being sent to the sawing position by the feeding mechanism 2, and then the motor is started, which drives the worm 3 to rotate. The worm drives the worm wheel 4 to rotate, and the worm wheel drives the coaxial driving helical gear 5 to rotate. The driving helical gear 5 drives the driven helical gear 6 on the output shaft 8 to rotate. The driven helical gear on the output shaft drives the main shaft 9 to rotate, and the main shaft drives the saw blade 7 to rotate. At the same time, the gearbox 11 and the main shaft box 12 move along the crossbeam to complete the processing of the steel plate 1 by the saw blade 7.

[0024] Example 2: The difference from Example 1 is that, as shown in Example 2... Figures 9 to 14 As shown (for ease of illustration), Figure 9 The motor housing, primary transmission mechanism, and central shaft of the drive helical gear were removed; Figure 13(The motor housing, driving helical gear, and driven helical gear are not shown, but the adjusting assembly and eccentric shaft are shown.) Based on Embodiment 1, a specific structure of the backlash adjustable mechanism is further provided, which includes a separately arranged driving helical gear 5, which is coaxially assembled from a thick gear 17 and a thin gear 18. The end face of the thick gear is integrally provided with a protrusion 19 for mounting the thin gear 18. The backlash adjustable mechanism also includes four sets of adjusting assemblies. Each set of adjusting assemblies includes a round pin 20, a semi-circular pin 21, and adjusting springs 22 fixed at both ends to the round pin and the semi-circular pin, respectively. The thin gear is provided with four elongated holes 23, through which the round pin 20 passes. A thick gear is inserted into the semi-circular hole at the edge of the round hole 23. A semi-circular pin abuts against the other semi-circular hole at the edge of the oblong hole. The radii of the round pin and the semi-circular pin are matched with the radius of the semi-circular hole of the oblong hole. The adjustable backlash mechanism also includes an eccentric shaft 24, which includes a stepped cylinder and a hexagonal head 25 integrally formed with the end of the stepped cylinder. The hexagonal head facilitates the rotation of the eccentric shaft with a hexagonal wrench. The eccentric shaft passes through the thin gear and is inserted into the thick gear. The thin gear has a through hole that matches it, and the thick gear has a blind hole that matches the eccentric shaft. The stepped cylinder has two sections: the section closest to the hexagonal head is inserted into the blind hole on the thick gear, and the section closest to the hexagonal head passes through the thin gear. An annular cover plate 16 is installed on the end face of the thin gear to block the oblong hole. The spring is selected as 60Si2MnA or 50CrVA.

[0025] During assembly, we first insert the thin gear onto the protrusion on the end face of the thick gear. We then insert four round pins through the four elongated holes on the end face of the thin gear into the pre-machined pin holes on the end face of the thick gear. Next, we insert semi-circular pins into the elongated holes. Finally, we cover the four elongated holes with cover plate 16 to prevent the springs from popping out under pressure. Next, we freely insert the eccentric shaft 24 into the hole of the thick gear. Since the rotation direction is controlled by four springs pressing against their respective elongated pins, we need to use a wrench to clamp the hexagonal head of the eccentric shaft 24 and rotate it in the direction of spring compression to make the tooth profiles of the thick and thin gears coincide. When the tooth profiles of the thick and thin gears coincide, we install the thin gear into the drive shaft and mesh it with the driven helical gear on another shaft. At this point, the eccentric shaft is rotated to its free position and removed. The compressed spring returns to its free position. Because one end of the pin is fixed to the thick gear, the thick gear rotates in one direction, its teeth pressing against one face of the meshing gear. The other end of the spring 22 presses against the thin gear, causing the thin gear to rotate. The thin gear presses against the adjacent faces of the adjacent teeth of the meshing gear, i.e., the driven helical gear. This is equivalent to the spring separating one tooth each from the thick and thin gears, pressing against the two adjacent faces of the meshing gear's tooth groove. This is equivalent to the gear train's backlash disappearing. Whenever backlash or impact occurs in the gear train, the driven helical gear, meshing with the backlash adjustment mechanism between the thick and thin gears, compresses the spring within the thick and thin gears, thus buffering the impact and eliminating most of the backlash in the gear train.

[0026] Because the semicircular pin is set inside the elongated hole of the thin gear, and the elongated pin passes through the elongated hole and is inserted into the thick gear, the backlash adjustable mechanism can achieve better adaptive adjustment. When the thin gear has a small relative initial displacement to the thick gear during the high-speed operation of the secondary transmission mechanism, the semicircular pin slides relative to the end face of the thick gear. This ensures that when the spring in the adjusting component rotates slightly due to the high-speed operation of the secondary transmission mechanism, the entire adjusting component rotates around the elongated pin as the axis, thus preventing the spring from failing prematurely and achieving better adaptive adjustment.

[0027] Comparative Example 1: Only a single-stage worm gear drive is used, meaning the motor directly drives the spindle to rotate via the worm gear reduction. The rest of the structure is the same as in Example 1. Experimental results show that, due to the large diameter of the worm gear, the distance between the bottom wall of the gearbox and the worktable surface is only 60mm to 65mm. Under the condition of a saw blade diameter of 360mm, the maximum cutting thickness is only 65mm, which cannot meet the requirements for processing 100mm steel plates.

[0028] Comparative Example 2: A three-stage helical gear transmission is used instead of a worm gear transmission. This scheme increases the axial length of the gearbox by approximately 40%, the overall weight by 25%, and the transmission efficiency decreases by approximately 8% due to the increased number of gears.

[0029] It can be seen that the present invention, through the combination of a first-stage worm gear transmission and a second-stage helical gear transmission, combined with a specific center distance parameter (90mm) and a backlash adjustment function, breaks through the cutting thickness limitation under a fixed saw blade diameter while ensuring transmission compactness and efficiency, and has made significant technological progress.

[0030] Example 3: The difference from Example 1 is that, as shown in Example 3... Figures 15 to 17 As shown, multiple radial oil-throwing grooves 401 are evenly distributed circumferentially on one or two axial end faces of the worm gear 4. The starting end of the oil-throwing groove 401 is close to the hub, and the end extends to the edge of the tooth tip circle of the worm gear 4. A wall thickness of 3-5 mm is left between the bottom of the oil-throwing groove 401 and the tooth root circle of the worm gear 4 to ensure structural strength. The opening direction of the oil-throwing groove 401 forms an angle of 30°-45° with the rotation direction of the worm gear 4, forming a flow guiding structure similar to that of a centrifugal pump impeller. When the worm gear 4 rotates, the lubricating oil in the oil sump at the bottom of the gearbox 11 is scraped up by the oil-throwing groove 401 and thrown outward along the oil-throwing groove 401 under the action of centrifugal force. Because the tooth tip circle diameter of the worm gear 4 is large, its outer edge linear velocity is significantly higher than that of conventional designs, resulting in a stronger oil-throwing effect.

[0031] Given the structural defect that the large tip circle diameter of the first-stage worm gear 4 results in the lower bottom wall 1101 of the gearbox 11 being close to the worktable surface, this embodiment takes the opposite approach. The inner surface of the lower bottom wall 1101 of the gearbox 11 is designed as a shallow oil sump structure 1102, with a depth of 8-12 mm. The lowest point of this shallow oil sump 1102 is located directly below the worm gear 4, ensuring that the lower edge of the worm gear 4 is immersed in the oil sump to a depth of 3-6 mm.

[0032] The inner surface of the side wall of the housing is also provided with a spiral oil guide groove 1103. The oil guide groove 1103 starts from the oil sump 1102 area and extends along the tangential direction of the rotation direction of the worm gear 4 to the transmission area of ​​the secondary transmission mechanism (i.e., near the meshing position of the driving helical gear and the driven helical gear). The spiral angle of the oil guide groove 1103 is 15°~25°, which uses the airflow disturbance generated when the worm gear 4 rotates to assist in oil delivery.

[0033] Above the transmission area of ​​the secondary transmission mechanism, an oil collection box 111 is fixedly installed on the inner wall of the gearbox 11 housing, with the inlet end of the oil collection box 111 facing the direction of the worm gear 4's outward ejection. When the lubricating oil ejected by the rotating worm gear 4 splashes onto the oil collection box 111, the oil collection box 111 collects the oil and filters it through the built-in filter screen 1111. The oil is then transported via the oil pipe 112 to the oil nozzle 113, which is located directly above the meshing point of the driving helical gear and the driven helical gear. The filter screen 1111 is located at the oil inlet of the oil collection box 111, and the oil outlet of the oil collection box 111 is connected to the oil pipe 112. The oil nozzle 113 is installed at the end of the oil pipe 112 away from the oil collection box 111.

[0034] The oil injector 113 is a flat, fan-shaped nozzle, with its spray direction aligned with the inlet side of the meshing point, ensuring that the lubricating oil covers the tooth surface before the gear pair enters engagement. Excess lubricating oil flows back to the bottom oil sump 1102 under gravity, forming a complete circulating lubrication circuit.

[0035] To further utilize the heat dissipation potential of the large worm gear structure, this embodiment also provides heat dissipation fins 1104 on the outer surface of the lower bottom wall 1101 of the gearbox 11. Since the lower bottom wall 1101 is close to the worktable surface, the height of the heat dissipation fins 1104 is controlled within 15mm to avoid interference with the worktable surface. Simultaneously, ventilation slots are provided at corresponding positions on the worktable to utilize the airflow generated by the rotation of the saw blade during sawing to assist in heat dissipation.

[0036] The working principle is as follows: The motor drives the worm gear to rotate, which in turn drives a large-diameter worm wheel to rotate. The lower edge of the worm wheel is immersed in a shallow oil sump, carrying up the lubricating oil. Part of the oil forms a firmly adsorbed oil film on the tooth surface and enters the worm-worm wheel meshing area as the worm wheel rotates, forming a hydrodynamic oil film to support lubrication. The other part of the oil accumulates in the oil slinger groove on the outer edge of the worm wheel and is thrown outward under centrifugal force, forming a splash oil mist to lubricate the bearings and secondary transmission gears inside the housing.

[0037] Of the ejected lubricating oil, part is guided along the spiral oil guide groove to the transmission area of ​​the secondary transmission mechanism to achieve active oil delivery; the other part is captured by the oil collection box, filtered, and then precisely sprayed by the oil nozzle to the meshing point of the helical gear pair.

[0038] During its circulation, the lubricating oil carries away the heat generated by the worm gear pair and helical gear pair (i.e., the primary and secondary transmission mechanisms). The heat is dissipated to the surrounding environment through the heat dissipation fins on the gearbox housing wall and outer surface. The ventilation slots on the workbench further enhance the air convection cooling effect.

[0039] Existing technology shows that while worm gear drives can achieve a large reduction ratio in a single stage and thus provide high torque output within a relatively small structural space, the large tip circle diameter of the worm gear causes the bottom wall of the gearbox to be too close to the worktable surface. Given a fixed saw blade diameter, this directly limits the depth to which the saw blade can cut into the workpiece, making it difficult to meet the requirements for machining thick plates. While multi-stage helical gear drives can avoid this problem, the axial dimension of the gearbox increases significantly, resulting in a less compact structure, and the increased number of gears leads to a decrease in transmission efficiency.

[0040] Furthermore, while existing circular saws are relatively stable when sawing workpieces with diameters of φ10~150mm, they struggle to guarantee sawing accuracy when dealing with workpieces larger than φ200mm. For steel plate sawing, when the workpiece thickness varies significantly, traditional transmission systems lack adaptive adjustment capabilities, easily leading to unstable output and potential vibration during sawing. In addition, current circular saws mainly employ two feed methods: horizontal push and oblique push. The main structure of these two types relies on guide rail transmission, which, after prolonged use, can lead to guide rail wear, resulting in unstable gearbox output and vibration during sawing.

[0041] High reduction ratio transmissions, especially single-stage worm gear drives, present heat dissipation challenges. The worm and worm wheel teeth do not engage in rolling meshing but rather experience high-speed sliding friction. At these high speeds, the lubricating oil film is easily broken, leading to direct metal-to-metal contact. This intensifies wear and causes a rapid temperature rise. Furthermore, a higher reduction ratio results in fewer worm threads (typically single-threaded worms), a smaller worm lead angle, and a higher proportion of sliding speed. The purpose of a high reduction ratio is to increase torque; an output torque of 2500 N·m means the worm wheel teeth bear extremely high contact stress. Under high pressure, increased internal friction in the lubricating oil causes a rapid rise in oil temperature, creating a vicious cycle: increased oil temperature → decreased viscosity → thinner oil film → easier rupture → further temperature increase. Additionally, while the gearbox volume is compressed for a compact design, the large diameter of the worm wheel occupies a significant amount of internal space, leaving little remaining space. This results in less oil storage, lower heat capacity, and faster temperature rise. Moreover, the limited heat dissipation surface area and relatively fixed outer wall area further hinder heat dissipation. In actual operation of circular saws, high sliding speed and high contact stress result in a large amount of heat generated per unit time; insufficient oil storage and small heat dissipation area prevent timely heat dissipation, leading to excessively high temperatures when continuously sawing thick plates; high temperatures accelerate oxidation, reduce oil viscosity, and even cause coking, resulting in premature deterioration of the lubricating oil; oil film rupture causes early pitting or galling on the worm gear teeth; and asynchronous thermal expansion of the housing and gears leads to changes in backlash after shutdown and cooling, exacerbating the impact upon restarting, thus affecting gear meshing backlash due to thermal deformation after shutdown. Therefore, frequent shutdowns for cooling are necessary, reducing production efficiency.

[0042] This embodiment utilizes the inherent structural feature of the large tip circle diameter of the worm gear in the primary transmission mechanism to construct a complete lubrication and heat dissipation system. The structural feature commonly considered a defect in the art—the excessively large tip circle diameter of the worm gear leading to a lower bottom wall of the gearbox—is transformed into a driving source for the forced lubrication system and a favorable condition for the formation of the oil sump. The feature that originally limited the cutting thickness becomes key to improving lubrication performance. Moreover, without adding an additional oil pump or motor, the lubricant is drawn, delivered, and sprayed entirely by the rotation of the worm gear itself, reducing system energy consumption and potential failure points. Through the combination of the oil collection box and the nozzle, the lubricant is precisely delivered to the meshing point of the secondary helical gear, solving the problems of uneven oil supply at high speeds and insufficient oil supply at low speeds in traditional splash lubrication. The integrated lubrication and heat dissipation design utilizes the space limitation at the bottom of the gearbox created by the large-diameter worm gear to create a shallow oil sump and forced convection structure, reducing the thermal equilibrium temperature of the transmission system by approximately 15% to 20% under long-term heavy-load cutting conditions. All lubrication structures are integrated into the existing internal space of the gearbox, without adding additional external pipelines or devices, maintaining the compactness of the entire machine.

[0043] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A power transmission system for a steel plate circular saw, characterized in that, The system includes a motor, a gearbox, a spindle housing, a spindle, a saw blade, and a crossbeam. The motor is connected to the gearbox, and the gearbox is connected to the spindle housing. The spindle housing is inverted and mounted on a guide rail on the crossbeam. The saw blade is connected to the spindle. The system is characterized by: The gearbox includes a primary transmission mechanism and a secondary transmission mechanism. The primary transmission mechanism is a worm gear transmission mechanism; the secondary transmission mechanism is a helical gear transmission mechanism, which is coaxially arranged with the worm wheel of the primary transmission mechanism and is used to receive the power of the primary transmission mechanism and drive the main shaft to rotate. The vertical distance from the center of the output helical gear of the secondary transmission mechanism to the bottom wall of the gearbox is configured to be 90mm. Furthermore, the gearbox is equipped with a backlash adjustment mechanism, which acts on the helical gear pair of the secondary transmission mechanism to adjust the gear meshing backlash to reduce vibration and impact during the sawing process.

2. The power transmission system for a steel plate circular saw according to claim 1, characterized in that, The adjustable backlash mechanism includes a split-type driving helical gear in a two-stage transmission mechanism. The driving helical gear is coaxially assembled from a thick gear and a thin gear. The end face of the thick gear has an integrally formed protrusion for mounting the thin gear. The adjustable backlash mechanism also includes four sets of adjustment components. Each set of adjustment components includes a round pin, a semi-circular pin, and an adjustment spring that is fixedly connected to the round pin and the semi-circular pin at both ends. The thin gear has four elongated holes. The round pin passes through the semi-circular hole at the edge of the elongated hole and is inserted into the thick gear. The semi-circular pin abuts against the other semi-circular hole at the edge of the elongated hole. The radii of the round pin and the semi-circular pin are related to the semi-circular shape of the elongated hole. The radius of the hole is matched, and the adjustable backlash mechanism also includes an eccentric shaft. The eccentric shaft includes a stepped cylinder and a hexagonal head integrally formed with the end of the stepped cylinder. The eccentric shaft passes through the thin gear and is inserted into the thick gear. The thin gear is provided with a through hole that matches it, and the thick gear is provided with a blind hole that matches the eccentric shaft. The stepped cylinder has two sections. The section closer to the hexagonal head is inserted into the blind hole on the thick gear, and the section closer to the hexagonal head passes through the thin gear. An annular cover plate is installed on the end face of the thin gear to block the elongated hole. The eccentric shaft is used to adjust the relative phase between the thick gear and the thin gear during the assembly stage. After assembly, the constraint can be removed or released.

3. The power transmission system for a steel plate circular saw according to claim 2, characterized in that, The transmission ratio of the primary transmission mechanism is 1500:65, and the output torque reaches 2500 N.m; the diameter of the saw blade is 360 mm.

4. A circular saw for steel plates, characterized in that, The power transmission system for the steel plate circular saw as described in any one of claims 1 to 3 further includes a feeding mechanism, a discharging mechanism, a base, and a worktable. After the steel plate to be processed is conveyed to the sawing position on the worktable by the feeding mechanism, the power transmission system drives the saw blade to complete the sawing process.

Images