Turning tool prefabricated surface microgroove induced automatic chip breaking method

Abstract

The invention relates to a turning tool prefabricated surface microgroove induced automatic chip breaking method, which comprises the following steps of: before cutting machining, machining a microgroove structure which is spiral along the axial direction on the surface of a workpiece in advance by using a tool; during turning, the tool and the microgrooves act synergistically on the roots of the cuttings to construct a periodic stress concentration area, critical strain needed by cutting breakage is greatly reduced, meanwhile, the bending degree of the cuttings is increased, and then automatic breaking of the cuttings is achieved. And by controlling parameters such as the shape, the size and the spacing of the section of the microgroove, the high-toughness material can obtain a stable and reliable chip breaking effect. According to the method, precise control over the chip fracture process is achieved through the limit strain weakening effect, and the problem of continuous turning chip winding is fundamentally solved. And the method is deeply compatible with a turning numerical control system, and can be easily arranged in a process route to realize automatic chip breaking in the next process. Compared with a traditional chip breaking technology, the chip breaking method does not need additional devices, is easy to operate and is highly suitable for an intelligent unmanned turning production line.

Description

Technical Field

[0001] This invention relates to the field of high-strength and tough metal cutting technology, and in particular to a method for inducing automatic chip breaking by pre-grooving microgrooves on the surface of a lathe tool. Background Technology

[0002] High-strength and tough metal materials (such as stainless steel and titanium alloys) have characteristics such as high toughness, high strength and low thermal conductivity. During the turning process, they are prone to forming continuous chips that wrap around the workpiece or tool, resulting in problems such as reduced machining quality, accelerated tool wear and machine tool jamming.

[0003] Currently, conventional chip breaking methods (such as laser-assisted cutting and high-pressure cooling chip breaking) still have many limitations: (1) the applicable range of cutting parameters for chip breaking is narrow, and excessive adjustment can easily affect the machining quality; (2) chip breaking tools or textured tools can only work under specific cutting parameters, and the tools need to be replaced frequently after wear, increasing costs and downtime; (3) high-pressure cooling chip breaking requires a dedicated high-pressure cooling system, and the equipment investment and maintenance costs are too high; (4) laser-assisted chip breaking not only requires the redesign and modification of the original machine tool, but the strong light and high temperature generated in the process also pose certain safety hazards. In addition, there is a method that uses high-power fiber lasers to prepare microstructures on the workpiece surface to induce chip breaking. However, this method also has some drawbacks: (1) It requires a professional high-power laser, the connection between the laser equipment and the machine tool is complicated, the maintenance cost is too high, and the operation depends on professional technicians; (2) Laser pretreatment is required before each pass, and this process is difficult to integrate with the existing workpiece process route; (3) Frequent clamping is required, which leads to increased processing error and reduced production efficiency; (4) The high heat generated by laser grooving will form a heat-affected zone, which will cause changes in material structure and affect the processing quality and performance of the workpiece; (5) Laser energy fluctuations are prone to cause poor consistency of microgroove structure accuracy and unstable chip breaking effect.

[0004] In summary, existing chip breaking methods generally suffer from problems such as low chip breaking efficiency, poor versatility, complex equipment, high cost, and limited applicability, making it difficult to meet the needs of high-efficiency and high-quality processing. There is an urgent need for a simpler, more effective, and more universally applicable chip breaking technology. Summary of the Invention

[0005] To address the aforementioned problems, the present invention aims to provide a method for inducing automatic chip breaking by pre-grooving microgrooves on the surface of a lathe tool. This method effectively solves many problems associated with existing chip breaking techniques, such as expensive grooving equipment, complex operation, low grooving accuracy, easy leaving of heat-affected zones on the workpiece surface, difficulty in integrating microgroove preparation with existing processes, and the need for additional steps to increase production time.

[0006] The technical solution adopted in this invention is as follows: The present invention proposes a method for inducing automatic chip breaking by pre-fabricating microgrooves on the surface of a lathe tool. Before cutting, a microgroove structure along the axial direction is pre-machined on the surface of the workpiece using a tool. The method includes the following steps: S1, microgroove structure design; S2, machining process design; S3, microgroove machining; S4, cutting parameter setting; S5, turning; S6, quality inspection.

[0007] Furthermore, step S1 includes: designing the depth, width, spacing, and helix angle of the microgroove using finite element simulation software based on the material properties, cutting parameters, and processing requirements of the workpiece.

[0008] Furthermore, the spacing of the microgrooves is designed according to the desired chip length. s With chip breaking frequency f satisfy , n Main spindle speed v f This refers to the feed rate.

[0009] Furthermore, in step S2, the sequence and characteristics of existing processing techniques for workpieces of different shapes are fully considered, and microgroove processing is embedded into the key turning process of the workpiece.

[0010] Furthermore, step S3 includes: compiling a CNC program according to the designed microgroove structure parameters, setting the cutting depth and feed rate values, and using the tools in the tool magazine to engrave the predetermined spiral microgroove structure on the workpiece surface.

[0011] Furthermore, step S4 includes: determining basic cutting parameters according to machining requirements; the basic cutting parameters include the number of passes, spindle speed, feed rate, and depth of cut.

[0012] Furthermore, in step S5, during processing, the chip morphology is monitored in real time to ensure that the chips break as expected; and it is checked whether the broken chips are guided into the collection area by the spiral microgroove, and whether they accumulate near the workpiece or the tool.

[0013] Furthermore, in step S6, after the machining is completed, the surface quality of the workpiece and the chip morphology are detected, and the microgroove structure design and cutting parameters are optimized based on the detection results.

[0014] Furthermore, the groove depth of the microgroove structure is less than or equal to the cutting depth.

[0015] Compared with the prior art, the present invention has the following advantages: 1. The microgroove structure is completed by mechanical scribing, which improves machining efficiency by more than 50% and reduces equipment cost by more than 70% compared with laser grooving, and there is no thermal damage. 2. The microgroove size is flexible and can adapt to different material properties and processing requirements, with a wider chip breaking range; 3. This invention integrates the trough-making process into the workpiece processing route, solving the problems of high difficulty and low efficiency in trough-making; 4. This invention requires no additional equipment and can effectively solve the problem of chip entanglement. It is suitable for unmanned automatic turning production and can ensure the stability and efficiency of automated unmanned production. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the implementation process of the method of the present invention; Figure 2 This is a schematic diagram illustrating the chip-breaking principle of the method of the present invention; Figure 3 This is a structural schematic diagram of a stepped shaft-type part; Figure 4 This is a schematic diagram of a concave circular arc surface shaft-type part. Figure 5 This is a schematic diagram of a complex circular arc surface shaft-type part. Figure 6 This is a planar schematic diagram of the microgroove structure; Figure 7 This is a cross-sectional schematic diagram of the prefabricated microgroove structure on the surface of the workpiece; Figure 8 These are comparison images of chip morphology: Image a shows a cutting depth of 0.25mm, Image b shows a cutting depth of 0.3mm, and Image c shows a cutting depth of 0.35mm. Figure 9 This is a schematic diagram of the actual machining of the microgroove structure.

[0017] In the attached drawings, the following labels are used: 1-Lathe spindle; 2-Triangular chuck; 3-Stepped shaft workpiece; 4-Lathe tool; 5-Concave crankshaft workpiece; 6-Complex curved shaft workpiece; 7-Blank outline; 8-Microgroove structure; 9-Machining influence zone. Detailed Implementation

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] See appendix Figure 1-2The present invention proposes a method for inducing automatic chip breaking by pre-fabricating microgrooves on the surface of a lathe tool. Before cutting, a microgroove structure along the axial direction is pre-machined on the surface of the workpiece using a tool. When the tool performs turning on the workpiece, the presence of the microgroove structure creates a weak point in the chip. Under the dual action of the tool and the microgroove structure, the chip breaks at the microgroove due to stress concentration, thereby achieving periodic automatic chip breaking.

[0020] The method of this invention is applicable to high-strength and high-toughness metallic materials, including but not limited to stainless steel, titanium alloys and high-temperature alloys.

[0021] Specifically, the following steps are included: S1. Microgroove Structure Design: Based on the material properties of the workpiece, cutting parameters and processing requirements, finite element simulation software is used to design the cross-sectional shape, depth, width, spacing and helix angle of the microgroove structure, which can be flexibly and dynamically adjusted. The groove depth of the microgroove structure is less than or equal to the cutting depth; microgroove structures that are too deep or too shallow are not conducive to obtaining good cutting results.

[0022] The spacing of the microgrooves is designed according to the desired chip length. s With chip breaking frequency f satisfy , n Main spindle speed v f This refers to the feed rate.

[0023] The microgroove structure is machined using tools from a tool magazine. The spiral direction of the microgroove structure is consistent with the tool feed direction. The designed microgroove structure is etched onto the workpiece surface before each tool feed. The size and shape of the microgroove structure are precisely controlled by adjusting the tool angle and cutting parameters.

[0024] S2. Machining Process Design: Taking full account of the sequence and characteristics of existing machining processes for workpieces of different shapes, microgrooving is embedded into the key turning process of the workpiece. The machining of the microgrooving structure and the turning process are completed in the same CNC system, eliminating the need for additional grooving equipment and reducing the number of clamping operations and equipment changeover time caused by setting up additional microgrooving processes. Operation is simple and can be fully automated.

[0025] S3. Microgroove Machining: Based on the microgroove structure parameters designed in the above steps, compile a CNC program, set the cutting depth and feed rate, and use the tools in the tool magazine to carve the predetermined spiral microgroove structure on the workpiece surface.

[0026] S4. Cutting parameter settings: Determine the basic cutting parameters according to the machining requirements; the basic cutting parameters include the number of passes, spindle speed, feed rate and depth of cut.

[0027] S5. Turning: During machining, monitor the chip morphology in real time to ensure that the chips break as expected; and check whether the broken chips are guided into the collection area by the spiral micro-groove, and whether they accumulate near the workpiece or tool.

[0028] S6. Quality Inspection: After processing, the surface quality and chip morphology of the workpiece are inspected, and the microgroove structure design and cutting parameters are optimized based on the inspection results.

[0029] The core principle of this invention is as follows: Before each cutting operation, a microgroove is pre-engraved on the workpiece surface using a cutting tool. The size of the microgroove structure can be flexibly adjusted by regulating the cutting parameters. Its mechanism of action encompasses two aspects: First, it alters the stress distribution in the cutting zone, causing defects to form on the chip surface due to the presence of the microgroove, thus reducing the ultimate strain energy required for chip fracture. Second, the microgroove structure changes the chip flow direction, causing further bending during chip flow and increasing the degree of deformation. When the tool moves to the microgroove, stress concentration occurs at the chip root due to the microgroove, accelerating chip fracture. The fractured chips are discharged from the cutting zone along the spiral microgroove, avoiding contact with the machined surface and ensuring machining quality.

[0030] This means that the automatic fracture of the chip is achieved through the ultimate strain weakening effect. Specifically, the microgroove structure induces local stress concentration in the chip during the cutting process, thereby reducing the critical strain energy for chip fracture.

[0031] The present invention will be further described below with reference to specific embodiments: Example 1 Figure 3 This embodiment describes the machining of a titanium alloy stepped shaft part. This embodiment fully demonstrates the practical application of a pre-grooved surface microgroove-induced automatic chip breaking method integrated with the machining process. The microgroove machining and turning operations are controlled by the same CNC program. G-code instructions embed the microgroove markings into the spindle feed trajectory, achieving integrated grooving and cutting operations. Three different cutting depths (29.5mm, 29.4mm, and 29.3mm) were used to simulate the machining of titanium alloy stepped shaft parts with three different diameter variations. Using the presence or absence of a pre-grooved structure as the sole variable, the effectiveness of the pre-grooved microgroove-induced chip breaking method was evaluated by comparing the results of conventional turning and microgroove-induced chip breaking turning.

[0032] Step S1: The outer radius of the part has three different parts, and a three-pass cutting process is used. The specific cutting depth and workpiece diameter changes for each pass are shown in the table below:

[0033] Step S2: The cutting conditions are the same for all three passes, with the spindle speed set to 425 r / min and the feed rate to 0.1 mm / r. Based on the cutting elements and conditions in Step S1, the tool path is designed to feed from the outside in. This design can effectively utilize the cutting force, reduce tool wear, and ensure machining accuracy.

[0034] Step S3: Before each pass, machine the surface of the workpiece as shown in the image. Figure 6 The microgroove structure is shown. Based on the high strength and toughness of titanium alloy and the results of finite element simulation, the microgroove depth is set to 0.25 mm. The microgroove orientation is designed as a spiral distribution along the workpiece axis to ensure smooth chip removal. The cross-sectional shape of the microgroove is chosen as a U-shaped groove, which has a good stress concentration effect.

[0035] Step S4: The microgrooves are machined using a cutting tool, such as... Figure 1 As shown, a dedicated turning tool from the tool magazine is used for machining. During the machining process, the feed rate and depth of cut are precisely controlled to ensure that the microgroove depth is accurately controlled within the set range. Figure 7 This is a cross-sectional view of the surface morphology of the microgroove structure, where h is the microgroove depth and w is the microgroove width, both of which are precisely controlled by the tool structure and cutting parameters. d represents the residual stress influence zone after machining the microgroove, which is controlled to a minimum by optimizing the microgroove parameters.

[0036] Step S5: During the first cut on the workpiece, when the tool moves to the microgroove, the presence of the surface microgroove structure causes defects on the workpiece surface, reducing the ultimate strain energy for chip fracture. Simultaneously, the presence of the microgroove also increases the bending radius of the chip, further promoting automatic chip fracture.

[0037] During the second and third passes, the microgroove machining and cutting operations described above are repeated, with the microgroove depth remaining at 0.25 mm, and the microgroove depth always kept less than or equal to the cutting depth.

[0038] Step S6: During the machining process, monitor the chip morphology in real time to ensure that the chips break as expected. After machining, evaluate the chip breaking effect by comparing the chip length and the quality of the machined surface.

[0039] Comparison of chip morphology after conventional turning and microgroove-induced chip breaking turning, as follows: Figure 8As shown in Figures a, b, and c, the chip morphology is as follows: Figures a, b, and c represent the chip morphology at cutting depths of 0.25 mm, 0.30 mm, and 0.35 mm, respectively. The left side of the figures shows the chips from microgroove-induced chip breaking turning, while the right side shows the chips from conventional turning. The comparison shows that the chip length from microgroove-induced chip breaking is shorter than that from conventional turning. Furthermore, at a cutting depth of 0.35 mm, conventional turning produces continuous chips and chip entanglement, while microgroove-induced chip breaking turning exhibits good chip breaking performance. These results demonstrate the effectiveness of pre-fabricated microgroove-induced chip breaking, and this method can ensure the continuity of automated turning processes.

[0040] The surface roughness of the workpieces machined by two turning methods was measured using a surface roughness measuring instrument. To ensure the accuracy of the measurement results, each sample was measured five times and the average value was taken. The results are shown in the table below.

[0041]

[0042] The comparison results showed that workpieces with microgrooves had better surface finish than those machined using conventional turning. This is because microgrooves induce chip breaking, which accurately controls chip length and prevents excessively long chips from entangled and scratching the machined surface. In conventional turning, chip entanglement occurs because the chips cannot be broken in time, resulting in better surface finish for workpieces with pre-fabricated microgrooves.

[0043] This method achieves microgroove machining through mechanical scribing, unlike the material modification mechanism of laser pretreatment. Its chip-breaking effect relies solely on geometric induction and does not involve changes to the material's physical properties. Because the microgroove depth is less than the cutting depth, the tool does not directly contact the microgroove structure on the workpiece surface during cutting, ensuring a smooth cutting process.

[0044] Example 2 This implementation example Figure 4 As shown, the difference from Embodiment 1 is that this embodiment uses a stepped arc surface, which, in addition to the stepped shaft portion, also includes a concave arc surface. The machining method for the stepped shaft portion is the same as in Embodiment 1. When machining the concave arc surface, the G02 (clockwise circular interpolation) command must be used to guide the tool along the arc trajectory to machine the microgroove structure. During machining, attention must be paid to the tool radius compensation setting. Based on the actual tool radius, the tool radius compensation command should be correctly used in the program to ensure the dimensional accuracy of the microgroove structure.

[0045] Example 3 This implementation example Figure 5 As shown, the difference from Embodiment 2 is that it has both convex and concave arc parts. When machining the concave arc, the G02 (clockwise arc interpolation) command is used, and when machining the convex arc, the G03 (counterclockwise arc interpolation) command is used to make the tool move along the arc trajectory to machine the micro-groove.

[0046] All matters not covered in this invention are common knowledge.

[0047] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for inducing automatic chip breaking by pre-grooving microgrooves on the surface of a lathe tool, characterized in that: Before cutting, a microgroove structure along the axial direction is pre-machined on the surface of the workpiece using a cutting tool; specifically, the following steps are included: S1, microgroove structure design; S2, machining process design; S3, microgroove machining; S4, cutting parameter setting; S5, turning machining; S6, quality inspection.

2. The method for inducing automatic chip breaking by pre-grooving microgrooves on the surface of a lathe tool according to claim 1, characterized in that: Step S1 includes: designing the depth, width, spacing and helix angle of the microgroove using finite element simulation software based on the material properties, cutting parameters and processing requirements of the workpiece.

3. The method for inducing automatic chip breaking by pre-grooving microgrooves on the surface of a lathe tool according to claim 2, characterized in that: The spacing of the microgrooves is designed according to the desired chip length. s With chip breaking frequency f satisfy , n Main spindle speed v f This refers to the feed rate.

4. The method for inducing automatic chip breaking by pre-grooving microgrooves on the surface of a lathe tool according to claim 2, characterized in that: In step S2, the sequence and characteristics of existing processing techniques for workpieces of different shapes are fully considered, and microgroove processing is embedded into the key turning process of the workpiece.

5. The method for inducing automatic chip breaking by pre-grooving microgrooves on the surface of a lathe tool according to claim 3, characterized in that: Step S3 includes: compiling a CNC program according to the designed microgroove structure parameters, setting the cutting depth and feed rate values, and using the tools in the tool magazine to engrave the predetermined spiral microgroove structure on the workpiece surface.

6. The method for inducing automatic chip breaking by pre-grooving microgrooves on the surface of a lathe tool according to claim 1, characterized in that: Step S4 includes: determining basic cutting parameters according to machining requirements; the basic cutting parameters include the number of passes, spindle speed, feed rate and depth of cut.

7. The method for inducing automatic chip breaking by pre-grooving microgrooves on a lathe tool according to claim 6, characterized in that: In step S5, during processing, the chip morphology is monitored in real time to ensure that the chips break as expected; and it is checked whether the broken chips are guided into the collection area by the spiral microgroove, and whether they accumulate near the workpiece or the tool.

8. The method for inducing automatic chip breaking by pre-grooving microgrooves on the surface of a lathe tool according to claim 7, characterized in that: In step S6, after the machining is completed, the surface quality and chip morphology of the workpiece are inspected, and the microgroove structure design and cutting parameters are optimized based on the inspection results.

9. The method for inducing automatic chip breaking by pre-grooving microgrooves on the surface of a lathe tool according to claim 2, characterized in that: The groove depth of the microgroove structure is less than or equal to the cutting depth.

Images