Optimization method for hot melt drilling multi-section filling cavity

Abstract

The application discloses an optimization method for processing a multi-section filling cavity by hot melting drilling, and the method guarantees constant temperature along an axial direction in the process of combining two metals, realizes close combination of the two metals, is suitable for filling cavities of bushings processed by hot melting drilling, guarantees same filling strength along the axial direction, improves the strength of a hole composed of the two metal materials, and reduces chemical corrosion.

Description

Technical Field

[0001] This invention relates to a technology in the field of machining, specifically an optimized method for hot melt drilling of multi-segment filling cavities. Background Technology

[0002] Hot melt drilling is a one-time processing technology that uses high temperature to form connecting holes in a stacked structure. Currently, there is little research on the design of filling cavities between metals. In actual production, straight-walled cavities are generally used. On the one hand, such cavities cannot fit the bushing shape well. On the other hand, the temperature of different points on the cavity along the axial direction is different, and the bonding strength of the metal materials is different at different points. This can easily lead to detachment during subsequent processing, affecting the quality of the final product. Summary of the Invention

[0003] To address the aforementioned shortcomings of existing technologies, this invention proposes an optimized method for hot-melt drilling of multi-segment filling cavities. Through the multi-segment filling cavity design, it ensures a constant temperature along the axial direction during the bonding process of the two metals, enabling a tight fit between the two metals. This method is suitable for hot-melt drilling of bushing filling cavities, ensuring the same filling strength along the axial direction, improving the strength of the hole composed of the two metal materials, and reducing chemical corrosion.

[0004] This invention is achieved through the following technical solution:

[0005] This invention relates to an optimized method for hot-melt drilling of multi-segment filled cavities, comprising:

[0006] Step 1) Design a three-section cavity structure including a straight-wall initial section, an inclined-surface contraction section, and a planar termination section;

[0007] Step 2) Construct a thermal model for the hot melt drilling process, specifically:

[0008] in: Let t be the temperature field in space, λ be time, ρ be the density of the object, c be the specific heat capacity of the object, and x, y, z be the coordinates of the object in the Cartesian coordinate system. Let α be the original heat distribution of the object in space, and α be the thermal conductivity.

[0009] Step 3) Solve the heat conduction model listed in Step 2) to obtain the slope and opening diameter parameters of the inclined contraction section of the three-segment cavity structure in Step 1), specifically including:

[0010] 3.1) Through formula derivation, the implicit equation in step 2) is derived into an explicit equation about the temperature field, and the temperature at different times at each point during the hot melt drilling process is solved to obtain isotherm diagrams at different times in the temperature field.

[0011] 3.2) Determine the upper and lower opening diameter parameters of the inclined plane contraction section based on the diameter of the hot melt drill and the processing parameters used in the actual processing.

[0012] 3.3) Based on the upper and lower opening diameters of the inclined plane contraction section determined in step 3.2), the required range is intercepted on the isotherm diagram obtained in step 3.1), and the slope of the inclined plane contraction section is calculated by linear fitting.

[0013] This invention relates to a multi-segment filling cavity obtained by the above-described method through hot melt drilling, comprising: a straight-wall initial segment, a sloped contraction segment, and a planar termination segment, wherein: the straight-wall initial segment is a straight segment structure, the slope of the sloped contraction segment and the diameters of the upper and lower openings, and the length parameters of the planar termination segment are obtained by the above-described method. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the structure of the present invention;

[0015] In the figure: 1. Straight wall initial section, 2. Inclined contraction section, 3. Planar termination section, 4. Material inner wall, 5. Material body, A1. Angle of the inclined contraction section, D1. Opening diameter of the straight wall initial section, D2. Closing diameter of the inclined contraction section, D3. Contraction diameter of the planar termination section, H1. Length of the straight wall initial section, H2. Length of the entire filling cavity from the inlet to the planar termination section, H3. Length of the entire material.

[0016] Figure 2 A schematic diagram of the isotherms in TC4 material when the temperature of the inner surface is 660℃ during the hot melt drilling process;

[0017] Figure 3 This is a schematic diagram of the fitting process for the inclined surface during hot melt drilling of TC4;

[0018] Figure 4 This is a schematic diagram of the filling cavity dimensions used in the TC4 process of hot melt drilling.

[0019] Figure 5 The image shows the filling effect obtained from an experiment using a hot melt drill to process a multi-segment filling cavity. Detailed Implementation

[0020] like Figure 1 As shown in this embodiment, a filling cavity for TC4 is processed by thermal drilling. The main thermal parameters of TC4 include thermal conductivity λ, specific heat capacity c, and density ρ. In this embodiment, λ = 7.955 W / m·K, c = 0.612 cal / g·℃, and ρ = 4.4 g / cm³. 3 .

[0021] This embodiment relates to an optimized method for machining multi-segment filling cavities using hot melt drilling, specifically including:

[0022] Step 1) Design a three-section cavity structure, which includes, from top to bottom: a straight wall initial section 1, an inclined contraction section 2, and a planar termination section 3, wherein: the inclination angle of the inclined contraction section 2 is A1, the opening diameter of the straight wall initial section is D1, the closing diameter of the inclined contraction section is D2, the contraction diameter of the planar termination section is D3, the length of the straight wall initial section is H1, the length of the entire cavity from the inlet to the planar termination section is H2, and the length of the entire material is H3.

[0023] Step 2) Construct a one-dimensional heat conduction model for the hot melt drilling process, specifically: a boundary value problem. Where: t is the temperature field in space, τ is time, x is the coordinate of the object in the Cartesian coordinate system, α is the thermal conductivity, and the excess temperature θ = tt w , t w Let t0 be the temperature at the interface between the thermal fusion drill and the BD, and t0 be the ambient temperature. This leads to the analytical solution equations for the one-dimensional heat conduction model:

[0024] That is: t(x,τ)=t w +erf(η)(t0-t w ), where: erf(*) is the error function,

[0025] Step 3) Solve the one-dimensional heat conduction model in Step 2) to obtain the parameters of the three-segment cavity structure. The specific steps are as follows:

[0026] Step 3.1) Solve the analytical solution equation of the one-dimensional heat conduction model using the analytical method, and use MATLAB to calculate the temperature at different times for each point to form isotherm plots at different times.

[0027] Step 3.2) Determine the upper and lower opening diameters of the inclined contraction section based on the diameter of the hot melt drill used in the actual processing and the processing parameters.

[0028] Step 3.3) Based on the upper and lower opening diameters of the inclined plane contraction section determined in Step 3.2), the required range is intercepted on the isotherm diagram obtained in Step 3.1), and the slope of the inclined plane contraction section is calculated by linear fitting.

[0029] Through specific experiments, the isotherms in TC4 at an inner wall temperature of 660℃ were calculated using MATLAB. Figure 2As shown, the target temperature is set to 400℃. Therefore, fitting is performed on this isotherm. First, the minimum distance x1 is obtained based on the inner wall diameter D3. The corresponding heat transfer time t1 is read from the isotherm. Based on the feed rate of the thermal drill and the overall cavity length D3, the time required for the thermal drill to completely pass through the filling cavity is calculated, thus obtaining t2. The radial distance at this time is read from the isotherm as x2. Therefore, the inclined contraction section within the range of x1 to x2 on the isotherm is the desired segment. Straight-line fitting is then performed to obtain the final filling cavity dimensions, as shown. Figure 4 As shown. Under the same hot melt drill tool and machining parameters, the hot melt drill of this invention was used to machine multi-segment filling cavities, ensuring that the cavity filling gap was reduced to 14μm.

[0030] Compared with existing technologies, the multi-segment filling cavity machining obtained by the hot melt drill through the optimization of the present invention ensures good filling strength and fewer gaps.

[0031] The above-described specific implementations can be partially adjusted by those skilled in the art in different ways without departing from the principles and purpose of the present invention. The scope of protection of the present invention is defined by the claims and is not limited to the above-described specific implementations. All implementation schemes within the scope of the claims are bound by the present invention.

Claims

1. An optimized method for hot-melt drilling of multi-segment filling cavities, characterized in that, include: Step 1) Design a three-section cavity structure including a straight-wall initial section, an inclined-surface contraction section, and a planar termination section; Step 2) Construct a thermal model for the hot melt drilling process, specifically: ,in: t represents the temperature field in space. For time, The density of the object, Let x, y, z be the specific heat capacity of the object, and x, y, z be the coordinates of the point on the object in the Cartesian coordinate system. This refers to the original heat distribution of an object in space. Thermal conductivity; Step 3) Solve the heat conduction model listed in Step 2) to obtain the slope and opening diameter parameters of the inclined contraction section of the three-segment cavity structure in Step 1), specifically including: 3.1) Through formula derivation, the implicit equation in step 2) is derived into an explicit equation about the temperature field, and the temperature at different times at each point during the hot melt drilling process is solved to obtain isotherm diagrams at different times in the temperature field. 3.2) Determine the upper and lower opening diameter parameters of the inclined plane contraction section based on the diameter of the hot melt drill and the processing parameters used in the actual processing situation; 3.3) Based on the upper and lower opening diameters of the inclined plane contraction section determined in step 3.2), the required range is intercepted on the isotherm diagram obtained in step 3.1), and the slope of the inclined plane contraction section is calculated by linear fitting. The explicit equations regarding the temperature field are obtained by constructing and solving a one-dimensional heat conduction model during the hot melt drilling process, specifically: a boundary value problem. Where: t is the temperature field in space, Let x be time, and let x be the coordinates of the object's point in the Cartesian coordinate system. Thermal conductivity, excess temperature: ,in: The temperature at the interface between the thermal drill and the BD contact point. Given the ambient temperature, the analytical solution equations for the one-dimensional heat conduction model are obtained: ,Right now: ,in: Let be the error function. ; The solution process specifically includes: solving the heat conduction equation of the hot melt drilling process analytically; using MATLAB to calculate the temperature at different times at each point to generate isotherm diagrams at different times; determining the upper and lower opening diameters of the inclined contraction section based on the actual hot melt drill diameter and processing parameters; and selecting the required range on the isotherm diagram based on the upper and lower opening diameters of the inclined contraction section, and calculating the slope of the inclined contraction section through linear fitting.

2. The optimized method for hot-melt drilling of multi-segment filling cavities according to claim 1, characterized in that, The parameters of the three-section cavity structure include: a straight-walled initial section 1, an inclined contraction section 2, and a planar termination section 3, wherein: the inclination angle A1 of the inclined contraction section 2, the opening diameter D1 of the straight-walled initial section, the closing diameter D2 of the inclined contraction section, the contraction diameter D3 of the planar termination section, the length H1 of the straight-walled initial section, the length H2 of the entire cavity filled from the inlet to the planar termination section, and the length H3 of the entire material.

3. A method for hot-melt drilling of multi-segment filling cavities, characterized in that, include: The structure comprises a straight initial segment, a sloping contraction segment, and a planar termination segment, wherein the straight initial segment is a straight segment structure, and the slope of the sloping contraction segment, the diameters of the upper and lower openings, and the length parameters of the planar termination segment are obtained by the method described in claim 1 or 2.

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