A method for identifying milling of a bearing saddle reserved area

Abstract

The present application relates to the technical field of machining and metal structure identification, and particularly relates to a kind of identification milling machining method of bearing saddle reserved area, comprising: bearing saddle is cleaned and polished, obtains the three-dimensional size data of the reserved area on bearing saddle, and the reserved area is ruled to form positioning information;According to three-dimensional size data and positioning information, bearing saddle is clamped in numerical control milling machine and is milled to form font groove;Font groove is cleaned, degreasing;Filler material is added by welding method to form concave-convex font, bearing saddle is stress-relieved, and surface finishing is carried out;Bearing saddle is detected for bonding strength, until the detection result reaches preset threshold value (otherwise return to the foregoing step), and the identification of bearing saddle is completed.The present application controls the whole process through "precise positioning and milling, standardized welding combination, stress relief treatment and strength detection", guarantees the machining precision, and significantly improves the reliability and long-term stability of bearing saddle identification.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of machining and metal structure identification, and particularly relates to a method for identifying and milling a reserved area of a bearing saddle. BACKGROUND

[0002] A bearing saddle is a widely used bearing and fixing component in large equipment, mainly used in bearing and pipeline support of locomotives and vehicles, and precise mechanical devices. The surface of the bearing saddle usually needs to be provided with an identification mark to identify the position, model, parameter and other information in the subsequent assembly, maintenance and operation process. Common identification methods mainly include mechanical carving, chemical etching, spraying and label sticking.

[0003] In the prior art, a more commonly used process is to form an identification mark on the surface of the bearing saddle by using a numerical control carving machine or a manual lettering method. This method is relatively simple, but since the material is directly cut, stress concentration is easily generated in the machining area, and micro-cracks and burrs exist in the groove wall, thereby affecting the overall strength and service life of the bearing saddle. At the same time, the machining precision of the ordinary carving process is difficult to keep stable, especially on the curved surface or complex surface of the bearing saddle, the machining depth and groove width have deviations, resulting in insufficient identification clarity.

[0004] In addition, although the traditional spraying or label sticking method is simple in process, it has poor durability and is easily affected by high temperature, humidity, wear or corrosion and falls off in long-term operation, which is difficult to meet the demand for long-term reliable identification. The chemical etching process needs to use acidic or alkaline etching liquid, which not only has environmental pollution problems in the operation process, but also has difficulty in controlling the etching depth, and the consistency and stability of the identification are poor.

[0005] In recent years, some researches have also tried to form raised or recessed characters on the surface of the bearing saddle by using welding or laser cladding technology, but the related process path lacks systematic design. For example, there is no complete process flow in the aspects of workpiece pretreatment, groove control, cleaning and surface roughening treatment, welding parameter control and post-welding treatment, resulting in insufficient consistency and reliability of the identification formation.

[0006] In summary, the existing bearing saddle identification machining method has the following problems:

[0007] Mechanical carving process is prone to micro-cracks and stress concentration, and has insufficient machining precision and durability;

[0008] Spraying and label sticking methods have poor adhesion, and the identification is easily detached;

[0009] The chemical etching process has the problems of environmental pollution and difficulty in controlling the etching depth;

[0010] The application of welding or cladding lacks a standardized supporting process flow, and it is difficult to guarantee the forming quality and bonding strength of the mark.

[0011] Therefore, there is still a need to propose a new mark processing method for the reserved area of the bearing saddle, which can realize systematic control in the process steps, improve the reliability and long-term stability of the mark while ensuring the processing precision. SUMMARY

[0012] In order to overcome the above technical defects, the purpose of the present application is to provide a mark milling processing method for the reserved area of the bearing saddle, which can significantly improve the reliability and long-term stability of the mark of the bearing saddle through the whole process control of "accurate positioning and milling, standardized welding combination, stress relief treatment and strength detection", while ensuring the processing precision.

[0013] The application discloses a mark milling processing method for the reserved area of the bearing saddle, comprising the following steps:

[0014] Step S100: surface pretreatment and positioning of the bearing saddle, cleaning and polishing the bearing saddle, using high-precision measuring equipment to obtain three-dimensional size data of the reserved area on the bearing saddle, and marking lines on the reserved area according to design requirements to form positioning information for subsequent processing;

[0015] Step S200: groove milling, according to the three-dimensional size data and positioning information obtained in step S100, clamping the bearing saddle on a numerical control milling machine, and selecting a milling cutter with a diameter of 0.8 times or less than the minimum width of the reserved area, and milling the reserved area to form a font groove with a processing precision of ±0.05mm;

[0016] Step S300: font groove cleaning and sand blasting treatment, cleaning and degreasing the font groove formed in step S200, and on this basis, adopting a sand blasting process to treat the font groove surface, so that the roughness of the font groove surface is Ra3.2~Ra6.3μm;

[0017] Step S400: adding concave-convex font, adding filling material to form a concave-convex font in the font groove treated in step S300 by welding, and the welding parameters are formulaically controlled according to the size of the font groove and the diameter of the filling material;

[0018] Step S500: stress relief annealing and finishing, stress relief annealing the bearing saddle after adding the concave-convex font in step S400, and surface finishing;

[0019] Step S600: After the bearing saddle is processed in step S500, the bonding strength of the bearing saddle is detected. When the detection result does not reach the preset threshold, step S400 is executed to adjust the welding parameters and then process again until the detection result reaches the preset threshold, and the identification processing of the bearing saddle is completed.

[0020] Preferably, in the surface cleaning of the bearing saddle in step S100, a weak alkaline water-based cleaning agent is used for cleaning, the cleaning temperature is 40-50℃, and the cleaning time is 10-15min; during polishing, sandpaper with a particle size of 200-400 mesh is used, and the polishing direction is consistent with the long axis direction of the reserved area.

[0021] Preferably, in step S200, the milling tool is a hard alloy coated tool, and the blade corner radius of the hard alloy coated tool is less than 0.02mm; during milling, a water-based cutting fluid is used as a cooling and lubricating medium, the concentration of the water-based cutting fluid is 5%-8%, and the flow rate is 20-30L / min.

[0022] Preferably, in step S300, anhydrous ethanol or acetone is used for cleaning the font groove; the degreasing time is 1-3min, so that the surface of the font groove is cleaned before the sand blasting process is performed.

[0023] Preferably, in step S300, brown corundum sand is selected for the sand blasting process, and the particle size of the brown corundum sand is 40-60 mesh; the sand blasting pressure during the sand blasting process is 0.4-0.6MPa, and the sand blasting time is 3-5min.

[0024] Preferably, in step S400, the welding adopts build-up welding to add the concave-convex font, and the parameters of the build-up welding include:

[0025] The relationship between the build-up welding current I and the diameter d of the filler material is I=(10-15)×d, wherein the unit of I is ampere (A) and the unit of d is millimeter (mm); the voltage of the build-up welding is 20-30V, and the speed of the build-up welding is 10-20mm / min.

[0026] Preferably, in step S400, the welding adopts laser welding to add the concave-convex font, and the parameters of the laser welding include:

[0027] The relationship between the laser power P and the depth h of the font groove is P=(500-1000)×h; wherein the unit of P is watt (W) and the unit of h is millimeter (mm);

[0028] The width of the laser pulse is 0.5-2ms, and the frequency of the laser pulse is 10-50Hz;

[0029] The welding speed is 5-15mm / s;

[0030] The welding area adopts argon as a protective gas, and the flow rate of the protective gas is 10-15 L / min.

[0031] Preferably, the welding in step S400 adopts laser cladding to add the embossed font, and the cladding material is an alloy powder matched with the base body of the bearing saddle, and the particle size of the alloy powder is 150-300 mesh.

[0032] The laser power P of the laser cladding and the cladding layer thickness δ satisfy the relationship P=(1000-2000)×δ, wherein the unit of P is watt (W), and the unit of δ is millimeter (mm); the scanning speed is 5-15 mm / s, and the powder feeding rate is 5-10 g / min.

[0033] Preferably, the process conditions of the stress relief annealing in step S500 include:

[0034] The heating temperature is 550-650 DEG C, the holding time is 2-3 h, the heating speed is 50-100 DEG C / h, and the cooling speed is 30-50 DEG C / h.

[0035] Preferably, before step S200, the numerical control milling machine is also subjected to precision verification, and the positioning accuracy of the numerical control milling machine is ±0.02 mm, and the repeat positioning accuracy is ±0.01 mm.

[0036] After the above technical scheme is adopted, compared with the prior art, the following beneficial effects are obtained:

[0037] 1. The present application significantly improves the reliability and long-term stability of the bearing saddle mark by the whole process control of "precise positioning and milling, standardized welding, stress relief treatment and strength detection", while ensuring the machining precision;

[0038] 2. In the prior art (ordinary engraving process), the font groove size error is usually ±0.15-0.20 mm, which leads to unclear mark or even deformation; the present application adopts high-precision measurement positioning and numerical control milling process, and the control is within ±0.05 mm, and the optimal value is ±0.02 mm, so as to ensure the edge definition and consistency of the mark;

[0039] 3. In the prior art, the ordinary engraving process is only mechanical cutting, and the font and the bearing saddle are in a physical groove relationship, and the bonding strength is generally lower than 60 MPa; the present application forms a metallurgical bond in the font groove through welding or cladding, and the bonding strength can reach 100-135 MPa (increased by about 2-3 times), which greatly reduces the risk of font peeling or falling off;

[0040] 4. In the existing engraving process, the surface roughness of the groove bottom is about Ra12.5 μm without sand blasting treatment, and there is a problem of insufficient adhesion; the present application controls the roughness of the groove bottom to be Ra3.2-6.3 μm through the sand blasting process, which is more beneficial to the metallurgical bonding of the filling material and improves the interface reliability;

[0041] 5. The contrast test shows that the ordinary engraved mark has a service life of about times under the alternating load of ±150 MPa, and cracks or peeling appear; the mark of the present application has a service life of up to times under the same load, which is about 4-6 times higher, and the long-term use stability is greatly enhanced;

[0042] 6. In the prior art, the traditional engraving process has high dependence on the processing personnel, and there is an operation difference, which leads to poor consistency; the present application controls the welding and cladding parameters to be formulaic, so that the process parameters are matched with the font groove size, and the consistency and traceability between different batches of parts are ensured;

[0043] 7. In the prior art, the existing engraved mark is easy to blur or fail in high-temperature, vibration and corrosion environment; the mark of the present application is firmly combined with the base body after stress relief annealing and trimming treatment, and the high-temperature resistance and environmental interference resistance are significantly improved, which meets the long-term service requirement. BRIEF DESCRIPTION OF DRAWINGS

[0044] Figure 1 It is a step schematic diagram of the identification milling processing method of the bearing saddle reserved area of the present application. DETAILED DESCRIPTION

[0045] The advantages of the present application will be further described below in combination with the drawings and specific embodiments.

[0046] Hereinafter, exemplary embodiments will be described in detail with reference to the accompanying drawings. In the following description, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments are not representative of all embodiments consistent with the present disclosure. Rather, they are merely examples of devices and methods consistent with some aspects of the present disclosure as detailed in the appended claims.

[0047] The terms used in the present disclosure are merely for the purpose of describing specific embodiments, and are not intended to limit the present disclosure. The singular forms "a", "an" and "the" used in the present disclosure and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the term "and / or" used herein means and includes any or all possible combinations of one or more associated listed items.

[0048] It should be understood that, although the terms first, second, third, etc. can be employed in this disclosure to describe various information, such information should not be limited to these terms. These terms are only used to distinguish one category of information from another category of information. For example, without departing from the scope of the present disclosure, first information can also be referred to as second information, and similarly, second information can also be referred to as first information. Depending on the context, the word "if' as used herein can be interpreted as meaning "when" or "in response to determining" or "in response to ascertaining".

[0049] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "longitudinal", "transverse", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application.

[0050] In the description of the present application, unless otherwise specified and limited, it should be noted that the terms "mounting", "connecting", "connecting" should be understood broadly, for example, it can be mechanical connection or electrical connection, it can be the communication between two elements, it can be direct connection or indirect connection through intermediate medium, and the specific meaning of the above terms can be understood by those skilled in the art according to the specific circumstances.

[0051] In the subsequent description, the suffix such as "module", "component" or "unit" used to represent elements is only for the convenience of description of the present application, and has no specific meaning in itself. Therefore, "module" and "component" can be used interchangeably.

[0052] Referring to Figure 1 As shown, in this embodiment, a marking milling method for a reserved area of a carrier saddle will be described in detail, which specifically includes the following steps:

[0053] Step S100: surface pretreatment and positioning of the carrier saddle: cleaning and polishing the carrier saddle, obtaining three-dimensional size data of the reserved area on the carrier saddle by using high-precision measuring equipment, and marking the reserved area according to design requirements to form positioning information for subsequent processing. The step S100 is specifically:

[0054] The surface of the bearing saddle is cleaned and polished to remove the surface oxidation layer, oil stains and impurities; a weak alkaline water-based cleaning agent is used for surface cleaning, the cleaning temperature is controlled at 40-50℃, and the cleaning time is 10-15 min; the polishing uses sandpaper with a mesh size of 200-400, the polishing direction is consistent with the long axis direction of the reserved area to ensure the stability of the roughness of the processed surface; a high-precision measuring device (such as a laser scanner or a three-coordinate measuring machine) is used to obtain the three-dimensional size data of the reserved area of the bearing saddle; according to the design requirements, the reserved area is marked to form positioning information for subsequent milling.

[0055] Step S200: Milling into a groove, according to the three-dimensional size data and positioning information obtained in step S100, the bearing saddle is clamped on a numerical control milling machine, and a milling tool with a diameter of 0.8 times or less of the minimum width of the reserved area is selected to mill the reserved area to form a font groove with a machining precision of ±0.05 mm. This step is specifically:

[0056] The bearing saddle is clamped on a numerical control milling machine; the numerical control milling machine is checked for accuracy before milling, with a positioning accuracy of ±0.02 mm and a repeated positioning accuracy of ±0.01 mm; according to the three-dimensional size data and positioning information obtained in step S100, a hard alloy coated tool with a diameter of 0.8 times or less of the minimum width of the reserved area is selected for milling, with a tool edge corner radius of less than 0.02 mm to reduce the cutting pattern; water-based cutting fluid is used as the cooling and lubricating medium during milling, with a concentration of 5%-8% and a flow rate of 20-30 L / min; through numerical control, a font groove with a machining precision of ±0.05 mm is formed.

[0057] Step S300: Font groove cleaning and sandblasting, the font groove formed in step S200 is cleaned and degreased, and on this basis, a sandblasting process is used for treatment, so that the surface roughness of the font groove is Ra3.2-Ra6.3 μm. This step S300 is specifically:

[0058] The font groove is cleaned and degreased, preferably using anhydrous ethanol or acetone, and the degreasing time is 1-3 min; after cleaning is completed and the font groove surface is ensured to be clean, a sandblasting process is used for surface roughening treatment; the sandblasting pressure during sandblasting process treatment is 0.4-0.6 MPa, and the sandblasting time is 3-5 min; through sandblasting treatment, the surface roughness of the font groove reaches Ra3.2-Ra6.3 μm to improve the adhesion of the filling material.

[0059] Step S400: Adding concave-convex font, filling material is added to the font groove treated in step S300 to form a concave-convex font by welding, and the welding parameters are formulaically controlled according to the size of the font groove and the diameter of the filling material. This step S400 is specifically:

[0060] The concave-convex font is added by welding in the font groove after step S300, and the parameters of the welding are controlled according to the size of the font groove and the diameter of the filling material.

[0061] The welding mode includes:

[0062] The surfacing mode: the current I and the diameter d of the filling material satisfy I=(10-15)×d, wherein the unit of I is ampere (A) and the unit of d is millimeter (mm); the voltage of the surfacing is 20-30 V, and the speed of the surfacing is 10-20 mm / min.

[0063] The laser welding mode: the laser power P and the depth h of the font groove satisfy P=(500-1000)×h; wherein the unit of P is watt (W) and the unit of h is millimeter (mm); the width of the laser pulse is 0.5-2 ms, the frequency of the laser pulse is 10-50 Hz; the welding speed is 5-15 mm / s; argon is used as the protective gas in the welding area, and the flow rate of the protective gas is 10-15 L / min.

[0064] The laser cladding mode: the cladding material is an alloy powder matched with the base body of the bearing saddle, and the particle size of the alloy powder is 150-300 mesh; the laser power P of the laser cladding and the thickness δ of the cladding layer satisfy P=(1000-2000)×δ, wherein the unit of P is watt (W) and the unit of δ is millimeter (mm); the scanning speed is 5-15 mm / s, and the powder feeding rate is 5-10 g / min.

[0065] Through the formula parameter control, the filling material can form a stable metallurgical bond on the wall of the font groove, and the bonding strength is improved.

[0066] Step S500: stress relief annealing and trimming, the bearing saddle after the addition of the concave-convex font in step S400 is subjected to stress relief annealing and surface trimming. The step S500 specifically includes:

[0067] The bearing saddle after the addition of the concave-convex font is subjected to stress relief annealing; the annealing process conditions include: heating temperature 550-650℃, holding time 2-3h, heating speed 50-100℃ / h, and cooling speed 30-50℃ / h;

[0068] The font surface is trimmed after annealing to ensure that the font surface is flat, beautiful and firmly combined with the base body.

[0069] Step S600: After the bearing saddle processed in step S500, the bonding strength is detected. When the detection result does not reach the preset threshold, step S400 is executed, and the welding parameters are adjusted for reprocessing until the detection result reaches the preset threshold, and the identification processing of the bearing saddle is completed. This step S600 specifically includes:

[0070] The bonding strength of the bearing saddle processed in step S500 is detected.

[0071] When the detection result does not reach the preset threshold, return to step S400, adjust the welding parameters and reprocess;

[0072] When the detection result reaches the preset threshold, it is determined that the identification processing of the bearing saddle is completed.

[0073] In order to further illustrate the identification milling processing method of the reserved area of the bearing saddle, the following will be specifically described by way of specific embodiments.

[0074] Example 1: Adding concave-convex font in the way of surfacing (parameter endpoint value 1)

[0075] Step S100: Surface pretreatment and positioning of the bearing saddle:

[0076] Use weak alkaline water-based cleaner (pH≈9), cleaning temperature 40℃, cleaning time 10min; sandpaper with 200 mesh is used for polishing, the polishing direction is consistent with the long axis of the reserved area; three-coordinate measuring instrument obtains three-dimensional size data (accuracy ±0.01mm) of the reserved area; after marking, positioning information is formed.

[0077] Step S200: Milling into groove:

[0078] Clamp the bearing saddle on the numerical control milling machine, check the positioning accuracy ±0.02mm; tool diameter=minimum width of reserved area×0.8; use hard alloy coated tool, blade corner radius 0.015mm; processing accuracy is controlled within ±0.05mm; cutting fluid: water-based cutting fluid concentration 5%, flow rate 20L / min.

[0079] Step S300: Font groove cleaning and sandblasting:

[0080] Cleaning agent: anhydrous ethanol, degreasing time 1min; sandblasting: brown corundum sand 40 mesh, pressure 0.4MPa, time 3min; surface roughness Ra3.2μm.

[0081] Step S400: Adding concave-convex font (surfacing):

[0082] Surfacing current I=10×d (d=1.0mm→I=10A); voltage 20V, speed 10mm / min; filling material is steel wire with diameter of 1mm.

[0083] Step S500: stress relief annealing and trimming:

[0084] Heating temperature 550℃, holding time 2h, heating rate 50℃ / h, cooling rate 30℃ / h.

[0085] Step S600: bonding strength detection:

[0086] Threshold value of bonding strength: ≥200MPa; if not up to standard, re-execute step S400, increase current to 12A.

[0087] Example 2: laser welding method for adding concave-convex characters (parameter endpoint value 2)

[0088] Step S100: surface pretreatment and positioning of the bearing saddle:

[0089] Cleaning agent: weak alkaline water-based cleaning agent, cleaning temperature 50℃, cleaning time 15min; polishing: grit 400 sandpaper, direction consistent with the long axis; three-dimensional measurement accuracy: ±0.008mm.

[0090] Step S200: milling into grooves:

[0091] Tool diameter = minimum width of reserved area × 0.7; blade corner radius 0.02mm; accuracy control within ±0.05mm; cutting fluid: water-based cutting fluid concentration 8%, flow rate 30L / min.

[0092] Step S300: character groove cleaning and sandblasting:

[0093] Cleaning agent: acetone, degreasing time 3min; sandblasting: brown corundum sand 60 mesh, pressure 0.6MPa, time 5min; surface roughness Ra6.3μm.

[0094] Step S400: concave-convex character addition (laser welding):

[0095] Laser power P = 1000 × h (h = 1mm → P = 1000W); laser pulse width 2ms, frequency 50Hz; welding speed 15mm / s; protective gas: argon, flow rate 15L / min.

[0096] Step S500: stress relief annealing and trimming:

[0097] Heating temperature 650℃, holding time 3h, heating rate 100℃ / h, cooling rate 50℃ / h.

[0098] Step S600: bonding strength detection:

[0099] Threshold value ≥250MPa; if not up to standard, adjust laser power to 1200W for reprocessing.

[0100] Example 3: Laser cladding method to add embossed font (intermediate value of parameters)

[0101] Step S100: Surface pretreatment and positioning of the bearing saddle:

[0102] Cleaning agent: weak alkaline water-based cleaning agent, temperature 45°C, time 12 min; sanding: grit 320 sandpaper, direction consistent with the long axis; accuracy of three-dimensional size data acquisition: ±0.009 mm; width of positioning line: 0.2 mm.

[0103] Step S200: Milling into grooves:

[0104] Verification positioning accuracy of numerical control milling machine: ±0.02 mm; tool diameter = minimum width of reserved area × 0.75; tool edge corner radius: 0.018 mm; machining accuracy: ±0.05 mm; cutting fluid: water-based cutting fluid concentration 6.5%, flow rate 25 L / min.

[0105] Step S300: Font groove cleaning and sandblasting:

[0106] Cleaning agent: mixture of anhydrous ethanol and acetone (volume ratio 1:1), degreasing time 2 min; sandblasting: brown corundum sand 50 mesh, sandblasting pressure 0.5 MPa, time 4 min; surface roughness: Ra 4.5 μm.

[0107] Step S400: Add embossed font (laser cladding):

[0108] Cladding material: alloy powder (matching the composition of the bearing saddle matrix), particle size 200 mesh; laser power P = 1500 × δ (δ = 1 mm → P = 1500 W); scanning speed 10 mm / s; powder feeding rate 8 g / min; protective gas: argon, flow rate 12 L / min.

[0109] Step S500: Stress relief annealing and trimming:

[0110] Heating temperature 600°C, holding time 2.5 h, heating rate 75°C / h, cooling rate 40°C / h.

[0111] Step S600: Bonding strength detection:

[0112] Threshold value ≥ 220 MPa; if not up to standard, adjust the laser power to 1600 W and re-clad.

[0113] Example 4: Mixed welding process to add embossed font

[0114] In this embodiment 4, the surfacing is combined with laser cladding, the surfacing is used to form an initial filling layer, and the laser cladding is used to form a dense layer on the surface layer to increase the font strength and aesthetics.

[0115] Step S100: bearing saddle surface pretreatment and positioning:

[0116] Cleaning temperature: 42°C, cleaning time: 11 min; polishing: grit 280 sandpaper; three-dimensional size acquisition accuracy: ±0.01 mm.

[0117] Step S200: milling into a groove:

[0118] Tool diameter = minimum width of reserved area x 0.78; accuracy control is ±0.05 mm; cutting fluid: water-based cutting fluid concentration 7%, flow rate 23 L / min.

[0119] Step S300: font groove cleaning and sandblasting:

[0120] Cleaning agent: anhydrous ethanol; sandblasting grit: 50 mesh, pressure 0.55 MPa; surface roughness: Ra 4.8 μm.

[0121] Step S400: adding concave-convex font (hybrid process):

[0122] Initial surfacing layer: current I = 12 A, voltage 22 V, speed 12 mm / min;

[0123] Surface laser cladding layer: laser power P = 1400 W, scanning speed 12 mm / s, powder feeding rate 7 g / min.

[0124] Step S500: stress relief annealing and trimming:

[0125] Temperature 590°C, holding time 2.5 h, cooling rate 40°C / h.

[0126] Step S600: bonding strength detection:

[0127] Threshold value ≥ 260 MPa; the font edge obtained by this method is smoother, and the anti-peeling performance is stronger.

[0128] Example 5: verification of batch processing conditions

[0129] Verify the differences in processing accuracy, surface roughness, bonding strength and fatigue life between the process of the application and the conventional engraving process of the prior art, as follows:

[0130] Experimental materials and equipment:

[0131] Bearing saddle blank: consistent material and size, 12 pieces in total; divided into the inventive group (A1, A2, A3 each 3 pieces) and the comparative group (B1, 3 pieces); numerical control milling machine: positioning accuracy ±0.02mm, repeat positioning accuracy ±0.01mm. Cleaning agent, sandpaper, sandblasting material: weak alkaline cleaning agent, sandpaper with granularity 200-400, brown corundum sand (40-60 mesh); welding equipment: surfacing power, laser welding machine, laser cladding machine; detection equipment: three-coordinate measuring machine, roughness meter, universal testing machine, fatigue test.

[0132] Experimental steps:

[0133] (A group: the method of the application):

[0134] Step S100: surface pretreatment and positioning:

[0135] A1: 40℃×10min cleaning → polishing granularity 200 → scribe positioning;

[0136] A2: 45℃×12min cleaning → polishing granularity 300 → scribe positioning;

[0137] A3: 50℃×15min cleaning → polishing granularity 400 → scribe positioning.

[0138] Step S200: milling into a groove:

[0139] A1: tool diameter = groove width ×0.8; water-based cutting fluid concentration 5%, flow rate 20L / min;

[0140] A2: tool diameter = groove width ×0.6; concentration 6.5%, flow rate 25L / min;

[0141] A3: tool diameter = groove width ×0.5; concentration 8%, flow rate 30L / min.

[0142] Step S300: font groove cleaning and sandblasting treatment:

[0143] A1: ethanol degreasing 1min → sandblasting pressure 0.4MPa, sandblasting time 3min;

[0144] A2: ethanol degreasing 2min → sandblasting pressure 0.5MPa, sandblasting time 4min;

[0145] A3: ethanol degreasing 3min → sandblasting pressure 0.6MPa, sandblasting time 5min.

[0146] Step S400: concave-convex font addition:

[0147] A1: surfacing current =10×d, voltage 20V, speed 10mm / min;

[0148] A2: build-up current = 12.5 x d, voltage 25 V, speed 15 mm / min;

[0149] A3: build-up current = 15 x d, voltage 30 V, speed 20 mm / min.

[0150] Step S500: stress relief annealing and trimming:

[0151] A1: 550°C x 2 h, heating rate 50°C / h, cooling rate 30°C / h;

[0152] A2: 600°C x 2.5 h, heating rate 75°C / h, cooling rate 40°C / h;

[0153] A3: 650°C x 3 h, heating rate 100°C / h, cooling rate 50°C / h.

[0154] Step S600: bonding strength detection:

[0155] If the bonding strength < 100 MPa, adjust the welding parameters and rework.

[0156] (B1 group: normal engraving process):

[0157] 1. Directly use an engraving tool to process the font groove on the surface of the bearing saddle;

[0158] 2. No sandblasting, filling welding and annealing are performed;

[0159] 3. After processing, clean with water as a control sample.

[0160] Detection method:

[0161] Dimensional accuracy: three-coordinate measurement, take 10 measurement points and average; roughness: roughness meter measures the groove bottom, take 3 times and average; bonding strength: universal testing machine shear test; fatigue strength: ± 150 MPa alternating load, detect crack or peeling cycle number.

[0162] Experimental results:

[0163] A1 (lower limit value): dimensional accuracy (mm) is ± 0.05, surface roughness (Ra, μm) is 6.3, bonding strength (MPa) is 105, fatigue life (cycle number) is ;

[0164] A2 (intermediate value): dimensional accuracy (mm) is ± 0.03, surface roughness (Ra, μm) is 3.2, bonding strength (MPa) is 120, fatigue life (cycle number) is ;

[0165] A2 (intermediate value): dimensional accuracy (mm) is ±0.02, surface roughness (Ra, μm) is 3.2, bonding strength (MPa) is 135, fatigue life (cycle times) is ;

[0166] B1 general engraving process: dimensional accuracy (mm) is ±0.20, surface roughness (Ra, μm) is 12.5, bonding strength (MPa) is 55, fatigue life (cycle times) is .

[0167] Experimental conclusion: as described above, the A group (the method provided by the present application) is better than the B group (the traditional engraving process) in all parameter ranges; especially in the bonding strength (increased by 2-3 times) and the fatigue life (increased by 4-6 times), the effect of the present application is more significant; the data results verify the significant technical effect of the surface pretreatment, precision milling, sand blasting, welding filling, annealing and other combined processes provided by the method of the present application.

[0168] It should be noted that the embodiments of the present application have better implementation, and do not limit the present application in any form, any skilled person in the art can change or modify the equivalent effective embodiments by using the disclosed technical content, as long as it does not deviate from the content of the technical scheme of the present application, any modification or equivalent change and modification of the above embodiments according to the technical essence of the present application, still belongs to the scope of the technical scheme of the present application.

Claims

1. A method for milling markings in a reserved area for a load-bearing saddle, characterized in that, Includes the following steps: Step S100: Surface pretreatment and positioning of the bearing saddle. The bearing saddle is cleaned and polished. The three-dimensional dimension data of the reserved area on the bearing saddle is obtained using a high-precision measuring device. The reserved area is marked according to the design requirements to form positioning information for subsequent processing. Step S200: Milling the groove. Based on the three-dimensional dimension data and positioning information obtained in step S100, the bearing saddle is clamped on a CNC milling machine, and a milling cutter with a diameter of 0.8 times or less than the minimum width of the reserved area is selected to mill the reserved area to form a font groove with a machining accuracy of ±0.05mm. Step S300: Cleaning and sandblasting of the font groove. The font groove formed in step S200 is cleaned and degreased, and then sandblasted to make the surface roughness of the font groove Ra3.2~Ra6.3μm. Step S400: Adding raised and recessed fonts. In the font groove processed in step S300, filler material is added by welding to form raised and recessed fonts. The welding parameters are controlled by formula according to the size of the font groove and the diameter of the filler material. Step S500: Stress-relief annealing and finishing. The bearing saddle after adding the raised and recessed fonts in step S400 is subjected to stress-relief annealing and surface finishing. Step S600: Combined with strength testing, the bearing saddle processed in step S500 is subjected to bonding strength testing. If the test result does not reach the preset threshold, step S400 is executed, the welding parameters are adjusted and the process is repeated until the test result reaches the preset threshold, and the marking of the bearing saddle is completed.

2. The milling method for marking the reserved area of ​​the bearing saddle according to claim 1, characterized in that, In step S100, the surface of the bearing saddle is cleaned with a weak alkaline water-based cleaning agent at a temperature of 40-50°C for 10-15 minutes. When polishing, sandpaper with a grit of 200-400 mesh is used, and the polishing direction is consistent with the long axis direction of the reserved area.

3. The milling method for marking the reserved area of ​​the bearing saddle according to claim 1, characterized in that, In step S200, the milling tool is a carbide-coated tool with a cutting edge radius of less than 0.02 mm. During the milling process, a water-based cutting fluid is used as the cooling and lubrication medium, with a concentration of 5% to 8% and a flow rate of 20 to 30 L / min.

4. The milling method for marking the reserved area of ​​the bearing saddle according to claim 1, characterized in that, In step S300, anhydrous ethanol or acetone is used to clean the font groove; the degreasing time is 1~3 minutes, so that the surface of the font groove is clean before sandblasting.

5. The method for milling the markings of the reserved area for the bearing saddle according to claim 1, characterized in that, In step S300, the sandblasting process uses brown fused alumina sand with a particle size of 40-60 mesh; the sandblasting pressure is 0.4-0.6 MPa and the sandblasting time is 3-5 min.

6. The method for milling the markings of the reserved area for the bearing saddle according to claim 1, characterized in that, In step S400, the welding process involves adding raised or recessed lettering using a surfacing welding technique. The parameters of the surfacing welding include: The relationship between the welding current I and the diameter d of the filler material is: I = (10~15) × d, where the unit of I is ampere (A) and the unit of d is millimeter (mm); the welding voltage is 20~30V and the welding speed is 10~20mm / min.

7. The method for milling the markings of the reserved area for the bearing saddle according to claim 1, characterized in that, In step S400, laser welding is used to add raised or recessed lettering. The parameters of the laser welding include: The relationship between the laser power P and the depth h of the font groove is P = (500~1000) × h; where P is in watts (W) and h is in millimeters (mm). The width of the laser pulse is 0.5~2ms, and the frequency of the laser pulse is 10~50Hz; The welding speed is 5~15mm / s; Argon gas is used as the protective gas in the welding area, and the flow rate of the protective gas is 10~15L / min.

8. The method for milling the markings of the reserved area for the bearing saddle according to claim 1, characterized in that, In step S400, the welding is performed by laser cladding to add raised and recessed lettering. The cladding material is an alloy powder that matches the substrate of the bearing saddle, and the particle size of the alloy powder is 150~300 mesh. The relationship between the laser power P and the cladding layer thickness δ is P = (1000~2000) × δ, where the unit of P is watts (W) and the unit of δ is millimeters (mm); the scanning speed is 5~15mm / s and the powder feeding rate is 5~10g / min.

9. The method for milling the markings of the reserved area for the bearing saddle according to claim 1, characterized in that, The stress-relief annealing process conditions in step S500 include: The heating temperature is 550~650℃, the holding time is 2~3h, the heating rate is 50~100℃ / h, and the cooling rate is 30~50℃ / h.

10. The method for milling the markings of the reserved area for the bearing saddle according to claim 1, characterized in that, Before step S200, the accuracy of the CNC milling machine is verified. The positioning accuracy of the CNC milling machine is ±0.02mm, and the repeatability is ±0.01mm.

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