Surface laser polishing method and device for jewelry processing

Abstract

The invention discloses a surface laser polishing method and device for jewelry processing, and relates to the technical field of jewelry processing. According to the method, the jewelry to be polished is fixed to a clamp, a quality detection module and a roughness detection module are started, and the surface quality and roughness data of the jewelry are collected. And the control system receives the data and calculates the laser action time and intensity required by each position according to a mathematical model. The laser is started, the control system controls the laser to polish the jewelry point by point according to a calculation result, and meanwhile, the cooling system is started to take away heat in time. In the polishing process, the operation states of the laser and the cooling system are monitored in real time, and stable operation of equipment is ensured. And after polishing is completed, the surface quality of the jewelry is detected, and the actual roughness is compared with the expected roughness. And if the deviation exists, carrying out secondary polishing on the deviation area until the quality standard is reached. The polishing precision is remarkably improved, excessive or insufficient polishing is avoided, and the jewelry surface quality consistency is improved.

Description

Technical Field

[0001] The invention relates to the technical field of jewelry processing, and in particular to a surface laser polishing method and device for jewelry processing. Background Art

[0002] The following problems exist during jewelry processing: (1) Different locations on the jewelry surface have different degrees of roughness. Using the same laser intensity for polishing and grinding may result in over-polishing or under-polishing; (2) Heat may be generated during laser polishing, causing thermal deformation or thermal damage to the jewelry surface.

[0003] In the face of the above problem (1), the existing method is to directly use a laser scanner to first scan the jewelry surface to generate roughness information of the jewelry surface, and then control the output power intensity of the laser polishing according to the roughness information of the jewelry surface, so as to perform polishing of different intensities according to the roughness of the jewelry surface. In the face of the above problem (2), the existing method is to equip a cooling device, such as an air cooling or water cooling system, to remove the heat during laser polishing through a large-scale heat dissipation method.

[0004] In the above solutions, the power intensity is adjusted only according to the surface roughness information, without considering the effect of the quality difference of different parts of the jewelry on the laser energy absorption and heat conduction. It may still be impossible to accurately control the polishing effect, resulting in quality damage in some areas or polishing not meeting expectations. In addition, the cooling effect of air cooling or water cooling system is limited, and uneven cooling may cause local thermal stress concentration, affecting the structural stability and surface quality of the jewelry. Summary of the invention

[0005] To solve the above technical problems, the present invention is achieved through the following technical solutions:

[0006] The present invention provides a surface laser polishing method for jewelry processing, comprising the following contents:

[0007] S1. Fix the jewelry on the fixture, start the quality detection module and the roughness detection module at the same time, collect the quality and roughness data of each position of the jewelry, and transmit them to the control system.

[0008] S2. The control system calculates the laser action time and intensity required for each position based on the preset algorithm and combined with the quality and roughness data, and controls the laser to polish the jewelry.

[0009] S2.1. Assume that the localized mass of heat dissipation at any point of the jewelry is m i , Roughness is R ai , determine the relationship between mass and thermal conductivity k based on material properties i =f(m i ).

[0010] The localized heat dissipation mass is the local total mass of the jewelry material within a preset heat dissipation radius r with the position point as the center.

[0011] S2.2. Combined with laser energy density formula And the heat conduction equation Constructing the optimization objective function Solve the optimal laser action time t at each position when the convergence condition of the objective function value J is met i and intensity P i .

[0012] P is the laser power, t is the action time, A is the spot area, R di is the expected roughness.

[0013] ρ: represents the material density, the unit is usually K / m 3 It describes the amount of matter contained in a material per unit volume. Different jewelry materials (such as gold, silver, copper, etc.) have different density values. Density affects the material's ability to absorb and store heat. During heat conduction, the greater the density, the more matter is contained in the same volume of material, and the temperature change is relatively small when absorbing the same amount of heat.

[0014] c: is the specific heat capacity of the material, in J / (kg·K). Specific heat capacity refers to the amount of heat absorbed or released by a unit mass of a substance when the unit temperature is increased or decreased. Specific heat capacity reflects the material's ability to hold heat, and different materials have different specific heat capacities. For example, water has a large specific heat capacity, and the temperature change is small when absorbing or releasing a large amount of heat; while the specific heat capacity of metals is relatively small, and the temperature change is more obvious when absorbing or releasing the same amount of heat. In jewelry processing, the specific heat capacity of jewelry materials determines its temperature change characteristics during laser heating and cooling.

[0015] Represents the partial derivative of temperature T with respect to time t, in units of K / s. It describes the rate of change of temperature over time at a certain position. During the laser polishing of jewelry, this partial derivative reflects how fast the temperature of the jewelry surface rises under the action of the laser or how fast the temperature drops during the cooling process. If the value of the partial derivative is large, it means that the temperature changes dramatically over time; otherwise, the temperature changes slowly.

[0016] is the Hamiltonian operator, which is used to describe the changes of physical quantities in space.

[0017] is the heat flux vector Where k is the thermal conductivity, in W / (m·K), which indicates the ability of the material to conduct heat. The larger the thermal conductivity, the easier it is for the material to conduct heat. Represents the temperature gradient, describing the rate and direction of temperature change in space. It reflects the conduction of heat inside the material due to uneven temperature, that is, the trend and intensity of heat transfer from high-temperature areas to low-temperature areas.

[0018] Q represents the laser heat source term, the unit is W / m 3 It indicates the laser energy absorbed by a unit volume of material per unit time, reflecting the energy input of the laser to heat the jewelry. When laser polishing jewelry, the value of Q depends on parameters such as laser power, spot size, pulse frequency, and the absorption characteristics of the jewelry material to the laser energy.

[0019] S3. During the polishing process, the cooling system works synchronously to remove the heat generated during the laser polishing of the jewelry.

[0020] S4. After polishing, the surface quality of the jewelry is tested, and the actual roughness is compared with the expected roughness. If there is a deviation, the cause is analyzed and the laser parameters are adjusted, and the deviation area is polished again until the jewelry polishing quality standard is met.

[0021] In addition, the above solution for the optimal laser action time t i and intensity P i The general process is as follows:

[0022] ① Determine parameters: Before calculation, it is necessary to determine the physical parameters of the jewelry material, including density ρ, specific heat capacity c, thermal conductivity k i With mass m i The relationship k i =f(m i ); clarify the relevant parameters of the laser, including the spot area A; set the expected roughness R di , and obtain the localized heat dissipation mass m at each position of the jewelry through the quality detection module and the roughness detection module i and roughness R ai .

[0023] ② Select numerical calculation method: Use finite element method for analysis and calculation, divide the jewelry into multiple small units, discretize the heat conduction equation in each unit, and transform the partial differential equation into a set of algebraic equations.

[0024] ③ Establish a set of equations and solve them iteratively: Combined with the laser energy density formula, according to the discretized heat conduction equation and the optimization objective function Establish a set of equations including laser action time t and intensity P. Use an iterative algorithm to solve, starting from a set of initial guess values, and continuously iterate the calculation to gradually reduce the value of the objective function J until the convergence condition is met.

[0025] When the iterative algorithm is used for solving, the initial guess value uses the laser time and intensity values ​​set based on experience.

[0026] In the iterative calculation, the convergence condition is that the change of the J value obtained by two adjacent iterative calculations is less than any preset minimum value.

[0027] ④ Result analysis: After the iterative calculation converges, the obtained t and P values ​​are the optimal laser action time t for each position. i and intensity P i .

[0028] The present invention provides a surface laser polishing device for implementing the above-mentioned jewelry surface laser polishing method. The laser polishing device includes a fixing fixture for firmly clamping the jewelry, a quality detection module for scanning and detecting the quality distribution of the jewelry, a roughness detection module for obtaining the roughness distribution of the jewelry surface, a laser for polishing the jewelry surface, a cooling system for assisting in cooling the jewelry polishing processing temperature, and a control system for processing each module and controlling the operation of the laser and the cooling system.

[0029] Preferably, the quality detection module uses an X-ray detection module or an ultrasonic detection module to detect the volume of the jewelry entity in the detection area, and obtains the jewelry quality distribution information in combination with the density parameter.

[0030] Preferably, the roughness detection module uses a high-precision laser displacement sensor that can quickly acquire surface roughness data.

[0031] Preferably, the cooling system comprises a micro-channel liquid cooling plate, which surrounds the bottom and periphery of the fixedly clamped jewelry.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] The present invention obtains the mass distribution and roughness distribution of jewelry through the quality detection module and the roughness detection module, analyzes and judges the heat conduction and rough polishing degree requirements of each position point of the jewelry itself, adjusts the laser parameters, utilizes the heat conduction of the jewelry itself, and controls the polishing time accordingly, thereby reducing the heat concentration destructive effect of laser polishing and ensuring the laser polishing efficiency, thereby significantly improving the polishing accuracy, avoiding excessive or insufficient polishing, and improving the consistency of the jewelry surface quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a schematic diagram of the configuration of the main components of the jewelry surface laser polishing device in the present invention.

[0035] Among them: 1-microchannel liquid cooling plate; 2-fixing fixture; 3-jewelry; 4-cooling pipeline; 5-displacement component; 6-quality detection module; 7-roughness detection module; 8-laser. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0037] Embodiment 1: Combination Figure 1 The laser polishing structure of the jewelry surface designed by the present invention is configured as follows:

[0038] The device is mainly composed of a fixing fixture 2, a quality detection module 6, a roughness detection module 7, a laser 8, a microchannel liquid cooling plate 1 of a cooling system, and a control system. The fixing fixture 2 is used to stabilize the jewelry 3; the quality detection module 6 uses an x-ray detection module or an ultrasonic detection module to detect the volume of the jewelry in the detection area, and combined with the density, the quality of the jewelry at different positions can be obtained; the roughness detection module 7 is a high-precision laser displacement sensor that can quickly obtain surface roughness data; the laser 8 is a pulse fiber laser that can flexibly adjust the pulse frequency, pulse width and power; the cooling system consists of a microchannel liquid cooling plate 1 surrounding the jewelry and the bottom. The control system is responsible for processing the data of each module and controlling the operation of the laser 8 and the cooling system.

[0039] Embodiment 2: The present invention aims to establish a heat conduction model to describe the heat transfer process of jewelry under the action of laser, consider the influence of mass distribution on the thermal conductivity coefficient, establish a laser-material interaction model, and study the changes of different laser parameters on the surface microstructure of jewelry. The specific polishing control and action process are as follows:

[0040] 1. Equipment assembly and debugging: Assemble the fixing fixture, quality detection module, roughness detection module, laser, cooling system and control system according to the structural design plan, connect the lines of each module and perform electrical debugging to ensure the normal operation of each module; calibrate the quality detection module and roughness detection module to ensure the accuracy of data collection.

[0041] 2. Data collection and processing: Place the jewelry to be polished on a fixed fixture, start the quality detection module and the roughness detection module, and collect the surface quality and roughness data of the jewelry. The control system receives the data, calculates the laser action time and intensity required for each position according to the mathematical model, and stores the data.

[0042] 3. Laser polishing and cooling: Start the laser, and the control system controls the laser to polish the jewelry point by point according to the calculation results. At the same time, the cooling system is turned on, and the microchannel liquid cooling plate works to remove heat in time. During the polishing process, the operating status of the laser and cooling system is monitored in real time to ensure stable operation of the equipment.

[0043] 4. Quality inspection and adjustment: After polishing, the surface quality of the jewelry is inspected and the actual roughness is compared with the expected roughness. If there is a deviation, the cause is analyzed and the laser parameters are adjusted, and the deviation area is polished again until the quality standard is met.

[0044] Embodiment 3: When actually solving the above optimization objective function to obtain the optimal laser action time and intensity, since more physical processes and material properties are involved, it is usually necessary to use numerical calculation methods and professional software. The following is the general process of theoretical calculation:

[0045] 1. Determine parameters: Before calculation, it is necessary to determine the physical parameters of the jewelry material, such as density ρ, specific heat capacity c, thermal conductivity k i With mass m i The relationship k i =f(m i ) etc.; clarify the relevant parameters of the laser, including the spot area A; set the expected roughness R di , and obtain the mass m of each position of the jewelry through the quality detection module and the roughness detection module i and roughness R ai .

[0046] 2. Select numerical calculation method: Common numerical calculation methods include finite element method, finite difference method, etc. Taking finite element method as an example, it divides jewelry into multiple small units and calculates the heat conduction equation on each unit. Discretization is performed to transform the partial differential equation into a system of algebraic equations.

[0047] 3. Establish a set of equations and solve them iteratively: Based on the discretized heat conduction equation and the optimization objective function Establish a system of equations including laser action time t and intensity P (P is the laser power, t is the action time, and A is the spot area). Since the equations are usually nonlinear, an iterative algorithm (such as Newton's iteration method) is used to solve them. Starting from a set of initial guess values ​​(such as the laser time and intensity set based on experience), the calculation is iterated continuously to gradually reduce the value of the objective function J until the convergence condition is met (such as the change in the J value obtained from two consecutive iterative calculations is less than a preset minimum value).

[0048] 4. Result analysis: After iterative calculation convergence, the obtained t and P values ​​are the optimal laser action time t for each position i and intensity P iBy analyzing these results, it is possible to clearly understand the laser operating parameters required to achieve the desired roughness at different locations on the jewelry. For example, for areas with larger mass and higher roughness, higher laser intensity and longer action time may be required; while for areas with smaller mass and lower roughness, lower laser intensity and shorter action time may be required.

[0049] 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 and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A surface laser polishing method for jewelry processing, characterized in that: S1. Fix the jewelry on the fixture, start the quality detection module and the roughness detection module at the same time, collect the quality and roughness data of each position of the jewelry, and transmit it to the control system; S2. The control system calculates the required laser action time and intensity for each position based on the preset algorithm and combined with the quality and roughness data, and controls the laser to polish the jewelry; S2.

1. Assume that the localized mass of heat dissipation at any point of the jewelry is m i , Roughness is R ai , determine the relationship between mass and thermal conductivity k based on material properties i =f(m i ); The localized heat dissipation mass is the local total mass of the jewelry material within the preset heat dissipation radius r with the position point as the center of the circle; S2.

2. Combined with laser energy density formula And the heat conduction equation Constructing the optimization objective function Solve the optimal laser action time t at each position when the convergence condition of the objective function value J is met i and intensity P i ; Where P is the laser power, t is the action time, A is the spot area, ρ is the material density, c is the specific heat capacity, T is the temperature, is the Hamiltonian operator, is the temperature gradient used to describe the rate and direction of temperature change in space, Q is the laser heat source term, R di is the expected roughness; S3. During the polishing process, the cooling system works synchronously to remove the heat generated during the laser polishing of the jewelry; S4. After polishing, the surface quality of the jewelry is tested, and the actual roughness is compared with the expected roughness. If there is a deviation, the cause is analyzed and the laser parameters are adjusted, and the deviation area is polished again until the jewelry polishing quality standard is met.

2. A surface laser polishing method for jewelry processing according to claim 1, characterized in that: Solve the optimal laser action time t i and intensity P i The general process is as follows: ① Determine parameters: Before calculation, it is necessary to determine the physical parameters of the jewelry material, including density ρ, specific heat capacity c, thermal conductivity k i With mass m i The relationship k i =f(m i ); clarify the relevant parameters of the laser, including the spot area A; set the expected roughness R di , and obtain the localized heat dissipation mass m at each position of the jewelry through the quality detection module and the roughness detection module i and roughness R ai ; ②Select numerical calculation method: Use finite element method for analysis and calculation, divide the jewelry into multiple small units, discretize the heat conduction equation on each unit, and transform the partial differential equation into a set of algebraic equations; ③ Establish a set of equations and solve them iteratively: Combined with the laser energy density formula, according to the discretized heat conduction equation and the optimization objective function Establish a set of equations including laser action time t and intensity P; The iterative algorithm is used to solve the problem, starting from a set of initial guess values, and iterating the calculation continuously to gradually reduce the value of the objective function J until the convergence condition is met; ④ Result analysis: After the iterative calculation converges, the obtained t and P values ​​are the optimal laser action time t for each position. i and intensity P i .

3. The surface laser polishing method for jewelry processing according to claim 2 is characterized in that: When the iterative algorithm is used to solve the problem, the initial guess value uses the laser time and intensity values ​​set based on experience.

4. The surface laser polishing method for jewelry processing according to claim 2, characterized in that: During iterative calculation, the convergence condition is that the change of J value obtained by two adjacent iterative calculations is less than any preset minimum value.

5. A surface laser polishing device for implementing the surface laser polishing method of claim 1, characterized in that: The laser polishing device includes a fixing fixture for firmly clamping the jewelry, a quality detection module for scanning and detecting the mass distribution of the jewelry, a roughness detection module for obtaining the surface roughness distribution of the jewelry, a laser for polishing the surface of the jewelry, a cooling system for assisting in cooling the temperature of the jewelry polishing process, and a control system for handling each module and controlling the operation of the laser and the cooling system.

6. The surface laser polishing device according to claim 5, characterized in that: The quality detection module uses a light detection module or an ultrasonic detection module to detect the volume of the jewelry entity in the detection area, and obtains the jewelry quality distribution information in combination with the density parameter.

7. The surface laser polishing device according to claim 5, characterized in that: The roughness detection module adopts a high-precision laser displacement sensor for quickly acquiring surface roughness data.

8. The surface laser polishing device according to claim 5, characterized in that: The cooling system includes a microchannel liquid cooling plate, and the microchannel liquid cooling plate surrounds the bottom and surroundings of the fixedly clamped jewelry.

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