A passive constant force output device based on a gravity source

Abstract

The application discloses a passive constant force output device based on a gravity source and relates to the technical field of grinding equipment.The device comprises a mounting base, a vertical guide mechanism, a floating grinding module, a gravity counterweight, a pulley transmission set and a flexible traction rope.The floating grinding module is slidably arranged on the vertical guide mechanism;one end of the flexible traction rope is connected with the gravity counterweight, and the other end of the flexible traction rope is connected with the floating grinding module after passing through the pulley transmission set fixed on the top of the mounting base; the gravity counterweight is suspended and arranged, and a constant upward traction force is exerted on the floating grinding module by the gravity counterweight through the flexible traction rope.The application utilizes the constant characteristics of the gravity vector, eliminates the defects of displacement attenuation of traditional spring force through a pure mechanical structure, and realizes high-precision constant force grinding on linear workpieces without a complex electrical control system, and is particularly suitable for contact network maintenance in a passive environment.

Description

Technical Field

[0001] This invention relates to the field of machining equipment technology, and specifically to a passive constant force output device based on gravity source for grinding the surface of linear workpieces (such as railway contact wires). Background Technology

[0002] In fields such as rail transit and power transmission, there are numerous linear metal structures suspended high in the air (such as overhead contact line conductors). Taking the overhead contact line conductors of electrified railways as an example, due to the long-term sliding friction and arc erosion of the pantograph, a hardened layer, oxide scale, and irregular wavy wear will form on the surface of the conductors. In order to ensure power transmission efficiency and extend the service life of the facilities, these conductor surfaces must be precision ground and repaired regularly.

[0003] In the grinding process, the constancy of grinding pressure (feed force) is the core factor determining the machining quality.

[0004] 1) Excessive pressure: This can lead to excessive cutting of the cross-section of the linear workpiece, reducing the mechanical strength of the wire, and even causing wire breakage.

[0005] 2) Insufficient pressure: It cannot effectively remove the hardened oxide layer or ablation pits, and the repair effect is not up to standard.

[0006] 3) Pressure fluctuations: can cause wavy “vibration marks” on the surface of linear workpieces, which in turn worsens the surface roughness.

[0007] In existing technologies, the common methods of applying force are mainly as follows, but all of them have obvious drawbacks: Spring-loaded mechanism: This is the simplest passive force application method. However, the spring-loaded mechanism has an inherent drawback of pressure varying with displacement, which can lead to uneven grinding depth.

[0008] Pneumatic / hydraulic active control systems utilize cylinders or hydraulic cylinders in conjunction with pressure sensors for closed-loop control. While maintaining relatively constant pressure, these systems are complex, requiring air compressors, hydraulic pump stations, solenoid valves, and controllers. In outdoor, high-altitude, or unreliable power environments (such as railway maintenance windows), the system's bulkiness and dependence on power supply severely limit its application. Furthermore, the static friction of the cylinder seals can cause a "creeping" phenomenon during minute feeds, resulting in sluggish response.

[0009] Furthermore, while some existing grinding equipment employs counterweight structures, these counterweights are typically only used to tension the drive belt or abrasive belt to compensate for its natural elongation. They do not directly convert the weight of the counterweight into grinding feed pressure on linear workpieces; the core grinding pressure still relies on active actuators such as cylinders or hydraulic cylinders. This hybrid "counterweight tensioning + pneumatic feed" mode remains dependent on air sources and complex control valve groups, and cannot overcome the inherent friction and creep problems of pneumatic actuators, thus failing to meet the demands of high-precision constant-force grinding.

[0010] Therefore, there is an urgent need in the field for a grinding device that is simple in structure, requires no external energy input, and can always output high-precision constant pressure when the grinding wheel is worn or when the linear workpiece is undulating. Summary of the Invention

[0011] The purpose of this invention is to provide a passive constant force output device based on a gravity source, solving the technical problem of how to achieve high-precision constant force grinding in harsh environments such as fieldwork, without stable power supply, and high-altitude linear workpiece maintenance, without relying on air sources, power supplies, and complex sensor closed-loop control, while also taking into account the technical challenges of automatic centering and contour following of linear workpieces. This invention utilizes the constancy of the direction and magnitude of the gravity vector, and through a low-friction mechanical transmission system, converts the gravity of the counterweight into a constant grinding pressure on the linear workpiece, thereby overcoming the shortcomings of traditional spring mechanisms with force attenuation and complex active control systems.

[0012] Specifically, the present invention provides a passive constant force output device based on a gravity source, comprising: Mounting base 1; A vertical guide mechanism 2 is mounted on the mounting base 1; The floating grinding module 3 is slidably connected to the vertical guide mechanism 2 and is used to apply constant pressure to the linear workpiece. Gravity counterweight 4 is used to provide a constant gravity source; The pulley drive assembly 5 is rotatably mounted on the top of the mounting base 1; And a force transmission component, one end of which is connected to the gravity counterweight 4, and the other end is connected to the floating grinding module 3 by passing around the pulley transmission group 5, so that the floating grinding module 3 is always driven by the gravity source to have an upward tendency to press against the linear workpiece. The device also includes a pair of contour guide wheels 8, symmetrically arranged on both sides of the top of the floating grinding module 3; wherein, the contour guide wheel 8 is provided with a groove for engaging a linear workpiece, and the highest point of the rim of the contour guide wheel 8 is higher than the grinding contact surface of the floating grinding module 3 in the vertical direction.

[0013] Furthermore, it also includes a damping stabilizer 7, which is connected in parallel between the floating grinding module 3 and the mounting base 1, for absorbing the vibration of the floating grinding module 3 during operation.

[0014] Furthermore, the damping stabilizer 7 is an asymmetric damping structure, in which the damping force in the downward pressure direction of the floating grinding module 3 is greater than the damping force in the upward reset direction; the damping stabilizer 7 includes a hydraulic damping rod, the piston of the hydraulic damping rod is provided with a one-way valve hole that runs vertically through it, and the one-way valve hole is provided with a valve plate that only allows hydraulic oil to flow unidirectionally from bottom to top.

[0015] Furthermore, the contour guide wheel 8 is made of nylon or polyurethane, and the cross-sectional shape of its outer peripheral groove is V-shaped or U-shaped.

[0016] Furthermore, the force transmission component is a flexible traction cable 6; the pulley transmission group 5 includes two coaxially arranged fixed pulleys, and the flexible traction cable 6 is provided with two corresponding cables, which pass around the two fixed pulleys and are connected to the left and right sides of the floating grinding module 3 respectively.

[0017] Furthermore, the gravity counterweight 4 adopts a modular counterweight structure, including a counterweight frame and several counterweight plates that can be detachably stacked on the counterweight frame. The counterweight frame is a tray structure with a vertical guide rod. The counterweight plates have a through hole in the center. Multiple counterweight plates are symmetrically connected and stacked on the guide rod through the through hole. The output pressure is adjusted by increasing or decreasing the number of counterweight plates.

[0018] Furthermore, the vertical guide mechanism 2 includes two precision linear guides symmetrically arranged on the mounting base 1, and the floating grinding module 3 slides with the precision linear guides via a slider.

[0019] Furthermore, the floating grinding module 3 includes an adaptive support, a drive motor, and a grinding wheel. The grinding wheel rotates under the drive of the drive motor, and the adaptive support is connected to the force transmission component.

[0020] Furthermore, the bottom of the mounting base 1 is provided with a quick-release mechanism, which is used to lift the gravity counterweight 4 in the non-working state to release the tension of the force transmission component.

[0021] The present invention also provides a method for grinding a wire-shaped workpiece using the above-described apparatus, comprising the following steps: S1. Install the device on the work vehicle; S2. Increase or decrease the mass of the gravity counterweight 4 to set the target grinding pressure; S3. Move the work vehicle along the direction of the linear workpiece, and guide the linear workpiece to achieve automatic centering through the contour guide wheel 8 at the top of the device. S4. The floating grinding module 3 rises to the surface of the linear workpiece under the traction of gravity source to perform grinding. S5. When it is necessary to stop the machine, the gravity counterweight 4 is lifted by external force to relax the force transmission component, and the floating grinding module 3 falls back and detaches from the linear workpiece under its own weight.

[0022] Compared with the prior art, the present invention has the following significant advantages: 1. Achieving high-precision constant force output: Utilizing the constant characteristics of the gravity vector, the mechanical coupling between the counterweight and the pulley system eliminates the pressure attenuation (elastic coefficient error) caused by the increase in displacement in traditional spring mechanisms. Experimental data shows that within a full stroke range of 10mm, the pressure fluctuation rate does not exceed 0.2%, effectively solving the problem of insufficient contact pressure caused by grinding wheel wear.

[0023] 2. Significantly Improved Dynamic Machining Stability: By introducing a unidirectional damping stabilizer into the system, the original "gravity-flexible cable" system is transformed from an unstable simple harmonic vibration state to a critically damped stable state. This asymmetric control strategy of "high damping during downward movement and low damping during upward movement" can absorb the high-frequency impact energy generated during grinding and suppress system resonance. Tests showed that the surface roughness Ra value of the linear workpiece was significantly reduced from 6.3 μm with the traditional device to 1.6 μm.

[0024] 3. Automatic centering and contouring capabilities: By setting contouring guide wheels higher than the grinding surface, the device has a pre-centering function when contacting linear workpieces (such as contact wires). The contouring guide wheels contact the linear workpiece before the grinding head, guiding the linear workpiece into the center of the V-shaped / U-shaped groove, avoiding damage to the linear workpiece caused by grinding eccentricity, and realizing passive adaptive tracking of linear workpieces with complex shapes and positions.

[0025] 4. Passive, environmentally friendly and highly reliable: The constant force pressure application link does not require electric drive or sensor feedback, and can still work normally under conditions without external power supply. It is especially suitable for special working conditions where a stable power supply cannot be provided, such as field maintenance of electric locomotive contact networks.

[0026] 5. Deep Collaboration of Multiple Mechanisms to Solve Systemic Problems: This invention is not a simple superposition of the aforementioned components, but rather solves the systemic problem of "stability in constant force grinding of linear workpieces" through deep collaboration of the gravity counterweight, vertical guide mechanism, contour guide wheel, and damping stabilizer. Specifically: the gravity counterweight provides an absolutely constant basic feed force, the vertical guide mechanism provides low-friction vertical floating compensation for the module, and the combination of the two ensures that the grinding pressure does not decrease with displacement; addressing the problem of rigid impact due to inertia in pure gravity floating systems during high-speed grinding, the damping stabilizer provides high damping to absorb impact when the module is compressed and descends, and low damping to ensure rapid contact when it rises, perfectly compensating for the dynamic instability of the gravity floating system; at the same time, the contour guide wheel is set higher than the grinding surface, achieving physical limitation and automatic centering before grinding contact, preventing grinding eccentricity, and ensuring that the constant gravity force always acts perpendicularly on the center of the linear workpiece. The above four elements are interdependent and indispensable, and together they construct a passive constant force grinding system that requires no external energy input, has high dynamic response, and has adaptive contouring capabilities. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below.

[0028] Figure 1 This is a schematic diagram of the overall structure of one embodiment of the present invention; Figure 2 These are enlarged schematic diagrams of partial structures of the floating grinding module in Embodiments 2 and 3 of the present invention; Figure 3 This is a schematic diagram of the modular structure of the gravity counterweight in an embodiment of the present invention.

[0029] Explanation of reference numerals in the attached drawings: 1-Mounting base; 2-Vertical guide mechanism; 3-Floating grinding module; 4-Gravity counterweight; 5-Pulley transmission group; 6-Flexible traction cable; 7-Damping stabilizer; 8-Contouring guide wheel. Detailed Implementation

[0030] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0031] Example 1: Description of the basic modules of the device of the present invention

[0032] like Figure 1 As shown, this embodiment provides a passive constant force output device based on a gravity source, the core of which lies in constructing a low-friction gravity balance system.

[0033] 1. Detailed description of mechanical structure

[0034] Mounting base 1: The lightweight and high-strength 6061 aluminum alloy profile is used to build a "gate" shaped frame, which ensures rigidity while reducing the weight of the equipment.

[0035] Vertical guide mechanism 2: A precision-grade (P-grade) linear rolling guide is selected and vertically installed on the inner column of the base 1. The slider is equipped with circulating balls with a friction coefficient of only 0.003-0.005, which is the key to ensuring the "soft floating" characteristic.

[0036] Floating grinding module 3: As an execution unit, it includes a slider base plate, a brushless DC motor (BLDC) mounted on the base plate, and a diamond grinding wheel connected to the motor shaft. The entire module is mounted on the guide rail slider.

[0037] Force transmission system: The pulley drive assembly 5 is mounted on the top of the base beam and integrates ceramic ball bearings to reduce rotational inertia. The flexible traction cable 6 is made of multi-strand aviation steel wire rope with a diameter of 3mm, which has extremely high tensile strength and extremely low elongation.

[0038] Gravity counterweight module: Please refer to the following: Figure 3 The gravity counterweight 4 adopts a modular structure, specifically including a counterweight base frame, a central guide rod vertically fixed to the center of the counterweight base frame, and several counterweight plates. Each counterweight plate has a central through-hole. In use, multiple counterweight plates are symmetrically stacked on the central guide rod through these through-holes. A force transmission component (such as a flexible traction cable 6) is connected to the top of the central guide rod. This structure allows for precise adjustment of the output pressure by adding or removing counterweight plates at any time.

[0039] 2. Working principle of constant force

[0040] In addition to the preferred flexible traction cable 6 with extremely low elongation, other embodiments may also use chain drive or rigid linkage with hinge as equivalent alternatives for gravity transmission.

[0041] This device follows the principles of classical mechanical equilibrium. Setting: The total mass of the floating grinding module 3 is M. module The mass of the gravity counterweight 4 is M. weight The acceleration due to gravity is g. When M weight >M module At that time, the feed pressure generated by the device on the upper linear workpiece is: F press =(M weight ·g)-(M module ·g)-f Where f is the system friction force. In fact, f = f rail +f pulley +f rope , where frail The friction force of the guide rail slider (calculated to be approximately 0.2 N based on an extremely low coefficient of friction of 0.003-0.005), f pulley The frictional force of the pulley bearing (approximately 0.1 N), f rope The bending resistance of the flexible cable is approximately 0.5 N. Therefore, it can be seen that after reducing f to less than 1 N using precision components within the system, F... press The pressure is determined solely by the mass difference between the two weight blocks. During the grinding process, whether the grinding wheel causes module 3 to move upward due to wear, or the contact wire causes module 3 to move downward due to bending, as long as the counterweight 4 does not touch the bottom, the parameters in the above formula remain unchanged. Therefore, under conditions of minimal system friction, the output pressure is determined solely by the counterweight mass and is independent of the displacement.

[0042] 3. Comparison of experimental data

[0043] To verify the results, we built a test platform in the laboratory. The test conditions were as follows: room temperature 25±2℃, vertical simulated displacement rate 0.5mm / s, and pressure data acquisition using a AVIC Electromechanical H3G S-type tension / compression sensor (range 10kg, overall accuracy ±0.1N). Each working condition was measured 5 times and the average value was taken. The target pressure was set to 50N.

[0044] Table 1: Comparison of the effects of vertical displacement on output pressure

[0045] Data shows that the present invention maintains a high degree of pressure consistency throughout the entire stroke range, overcoming the inherent defect of pressure attenuation with displacement in spring devices.

[0046] Example 2: Dynamic vibration suppression and surface quality improvement

[0047] Under high-speed grinding conditions, the mechanical system is prone to vibration. This embodiment is an improvement on embodiment 1.

[0048] 1. Structural improvements

[0049] like Figure 2 As shown, a damping stabilizer 7 is installed in parallel between the side of the floating grinding module 3 and the mounting base 1. This component uses a miniature hydraulic damping rod. To achieve an asymmetric damping mode, the piston of the hydraulic damping rod has a vertically penetrating one-way valve hole and a normally open damping micro-hole. The one-way valve hole is equipped with a valve plate that only allows hydraulic oil to flow in one direction from bottom to top.

[0050] When the floating grinding module 3 moves downward under pressure (in the direction of tool retraction / impact), the piston in the hydraulic damping rod is pressed down relatively, and the valve plate in the one-way valve hole is closed by the hydraulic oil. The hydraulic oil can only flow slowly through the normally open damping micro-hole, thereby providing a great damping force to absorb the cutting vibration and downward impact energy during grinding.

[0051] When the floating grinding module 3 moves upward (in the feed direction), the piston is pulled upward relative to the piston, and the valve plate in the one-way valve hole is opened by the hydraulic oil. The hydraulic oil can flow quickly through the one-way valve hole. At this time, the damping force is very small, ensuring that the grinding head can respond quickly and conform to the depression on the surface of the linear workpiece.

[0052] 2. Mechanism of action

[0053] When grinding wavy wear surfaces, without damping, the floating module will form a spring oscillator system under the action of elasticity and inertia, resulting in resonance (chatter). The function of the damping stabilizer 7 is to provide viscous resistance, dissipate vibration energy, and keep the system in a "critically damped" or "overdamped" state, ensuring that the grinding head smoothly adheres to the linear workpiece surface, rather than jumping on the surface.

[0054] 3. Effect Verification

[0055] A dynamic polishing test was conducted on a section of hard copper wire with a surface wave depth of 0.5 mm. It should be noted that the large fluctuations in the force values ​​without damping devices in Table 2 are not due to gravity attenuation, but rather to the inertial oscillation impact force generated by the system during high-speed reciprocating bonding.

[0056] Table 2: Surface Quality Comparison Data

[0057] The results showed that after adding the damping stabilizer, the device not only maintained constant force characteristics, but also significantly improved dynamic stability, enabling the surface quality of the machined surface to reach the precision standard.

[0058] Example 3: Adaptive contouring and engineering applications

[0059] To address the issue of uncertain positions of linear workpieces in field operations, this embodiment further adds a contouring function.

[0060] 1. Structural details

[0061] like Figure 2 As shown, a pair of contour guide wheels 8 are symmetrically installed on top of the floating grinding module 3, on both sides of the grinding wheel. The contour guide wheels 8 adopt a V-groove design with a groove angle of 120 degrees and are made of wear-resistant polyurethane. Their installation height is slightly higher than the cutting surface of the grinding wheel.

[0062] 2. Work Process

[0063] When the device is moved along the linear workpiece by the work vehicle: 1) Automatic centering: The V-groove first contacts the circular linear workpiece (such as contact wire), and uses the self-centering principle of geometry to forcibly correct the lateral position of the floating grinding module 3, ensuring that the grinding wheel center is always aligned with the center of the linear workpiece.

[0064] 2) Follow-up grinding: As the linear workpiece bends up, down, left, and right in space, the contour guide wheel 8 drives the entire floating grinding module 3 to float on the guide rail and make lateral fine adjustments (the base can be set with lateral degrees of freedom), realizing adaptive tracking blind operation without manual intervention.

[0065] In addition, to facilitate shutdown, a quick-release mechanism (not shown in the figure, but can be a cam-lifting structure) is installed at the bottom of the base. When it is necessary to stop the operation, the operator rotates the cam to lift the counterweight block 4, the traction cable 6 is instantly relaxed, and the grinding head falls back and detaches from the linear workpiece under its own weight, achieving a second-level rapid shutdown and preventing over-grinding damage caused by the grinding wheel staying at the same point for a long time.

[0066] Experimental conclusion: In the simulated 100-meter long track test, the device of this embodiment achieved full grinding coverage of the conductor with a left-right sway of ±15mm under simulated working conditions without human intervention, and no uneven grinding phenomenon occurred, which proves the excellent engineering adaptability of the device.

[0067] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A passive constant force output device based on a gravity source, characterized in that, include: Mounting base (1); A vertical guide mechanism (2) is provided on the mounting base (1); The floating grinding module (3) is slidably connected to the vertical guide mechanism (2) and is used to apply constant pressure to the linear workpiece; A gravity counterweight (4) is used to provide a constant gravity source; The pulley drive assembly (5) is rotatably mounted on the top of the mounting base (1); And a force transmission component, one end of which is connected to the gravity counterweight (4), and the other end is connected to the floating grinding module (3) by passing around the pulley transmission group (5), so that the floating grinding module (3) is always driven by the gravity source to have an upward tendency to press against the linear workpiece. The device also includes a pair of contour guide wheels (8), which are symmetrically arranged on both sides of the top of the floating grinding module (3); wherein, the contour guide wheel (8) is provided with a groove for engaging the linear workpiece, and the highest point of the rim of the contour guide wheel (8) is higher than the grinding contact surface of the floating grinding module (3) in the vertical direction.

2. The passive constant force output device based on a gravity source according to claim 1, characterized in that, It also includes a damping stabilizer (7), which is connected in parallel between the floating grinding module (3) and the mounting base (1) to absorb the vibration of the floating grinding module (3) during operation.

3. A passive constant force output device based on a gravity source according to claim 2, characterized in that, The damping stabilizer (7) is an asymmetric damping structure, and its damping force in the downward direction of the floating grinding module (3) is greater than its damping force in the upward reset direction; the damping stabilizer (7) includes a hydraulic damping rod, and the piston of the hydraulic damping rod is provided with a one-way valve hole that runs vertically through it, and the one-way valve hole is provided with a valve plate that only allows hydraulic oil to flow unidirectionally from bottom to top.

4. The passive constant force output device based on a gravity source according to claim 1, characterized in that, The material of the contour guide wheel (8) is nylon or polyurethane, and the cross-sectional shape of its outer peripheral groove is V-shaped or U-shaped.

5. A passive constant force output device based on a gravity source according to claim 1, characterized in that, The force transmission component is a flexible traction cable (6); the pulley transmission group (5) includes two coaxial fixed pulleys, and the flexible traction cable (6) is provided with two cables, which pass around the two fixed pulleys and are connected to the left and right sides of the floating grinding module (3).

6. A passive constant force output device based on a gravity source according to claim 1, characterized in that, The gravity counterweight (4) adopts a modular counterweight structure, including a counterweight frame and several counterweight pieces that can be detachably stacked on the counterweight frame. The counterweight frame is a tray structure with a vertical guide rod. The counterweight pieces have a through hole in the center. Multiple counterweight pieces are symmetrically connected and stacked on the guide rod through the through hole. The output pressure is adjusted by increasing or decreasing the number of counterweight pieces.

7. A passive constant force output device based on a gravity source according to claim 1, characterized in that, The vertical guide mechanism (2) includes two precision linear guides symmetrically arranged on the mounting base (1), and the floating grinding module (3) slides with the precision linear guides through a slider.

8. A passive constant force output device based on a gravity source according to claim 1, characterized in that, The floating grinding module (3) includes an adaptive bracket, a drive motor and a grinding wheel. The grinding wheel rotates under the drive of the drive motor, and the adaptive bracket is connected to the force transmission component.

9. A passive constant force output device based on a gravity source according to claim 1, characterized in that, The bottom of the mounting base (1) is provided with a quick unloading mechanism, which is used to lift the gravity counterweight (4) in the non-working state to release the tension of the force transmission component.

10. A method for grinding a wire-shaped workpiece using the apparatus of claim 8, characterized in that, Includes the following steps: S1. Install the device on the work vehicle; S2. Increase or decrease the mass of the gravity counterweight (4) and set the target grinding pressure; S3. Move the work vehicle along the direction of the linear workpiece, and first contact the linear workpiece through the contour guide wheel (8) at the top of the device and guide the linear workpiece to achieve automatic centering. S4. The floating grinding module (3) rises to the surface of the contact line workpiece under the traction of gravity source to perform grinding. S5. When it is necessary to stop the machine, the gravity counterweight (4) is lifted by external force to relax the force transmission component, and the floating grinding module (3) falls back and detaches from the linear workpiece under its own weight.

Images