A smart tool holder based on a groove structure for cutting force monitoring

Abstract

The present application belongs to the technical field of intelligent tool for metal processing, and provides an intelligent tool bar for cutting force monitoring based on groove structure, which comprises a tool bar, a plurality of groove groups are arranged on the side walls of the tool bar, a plurality of groove groups are arranged near the tool head position, a plurality of groove groups are used for local amplification of the strain of the tool bar under stress, the groove group comprises a plurality of triangular grooves opened on the side wall of the tool bar, and a plurality of triangular grooves form a rice-shaped groove structure; a plurality of film strain gauges, a plurality of film strain gauges are arranged correspondingly with a plurality of groove groups, and a plurality of film strain gauges are used for monitoring the strain condition of the tool bar under stress in different directions. The present application breaks through the intelligent bottleneck of the state of the metal processing tool, and meets the needs of the manufacturing field for continuous detection of cutting force with lower cost and higher reliability.

Description

Technical Field

[0001] This invention belongs to the field of intelligent cutting tool technology in metal processing, and particularly relates to an intelligent tool holder based on a groove structure for cutting force monitoring. Background Technology

[0002] Metal cutting is a comprehensive technology involving mechanical engineering, materials science, and other disciplines. It boasts advantages such as wide applicability, controllable machining accuracy, and high reliability, and is currently widely used in fields such as machinery manufacturing and aerospace. In recent years, with the development of precision manufacturing and intelligent manufacturing technologies, real-time monitoring of cutting forces has become particularly important. Real-time monitoring of cutting forces allows for control of cutting loads, optimization of cutting processes, evaluation of tool condition, and fault diagnosis and life prediction during the machining process, thereby improving the reliability of machining quality.

[0003] Currently, discrete devices are mainly used for cutting force measurement in the machining industry. These devices are relatively large, and their installation limits the size of workpieces that can be machined, thus restricting their application in actual machining processes. To address these issues, Chinese patent CN104139322A discloses an intelligent tool holder for four-dimensional cutting force monitoring. Its force-measuring component is connected to the tool holder via adhesive bonding. This connection method is prone to failure under high temperature and lubricating oil corrosion conditions, and the sensing position is relatively far from the machining position, resulting in a certain delay in the acquired data. Another example is Chinese patent CN115673800A, which proposes an intelligent tool holder for real-time monitoring of multi-dimensional cutting forces. This intelligent tool holder uses an arc-shaped structure to achieve strain amplification, but this structure has high requirements for the dimensional tolerances and assembly of each component, and it significantly affects the overall rigidity of the tool, negatively impacting machining accuracy. In summary, currently, there is no cutting force acquisition solution that is small in size, easy to manufacture, low in cost, and highly reliable, both domestically and internationally. Summary of the Invention

[0004] The purpose of this invention is to provide an intelligent tool holder based on a groove structure for cutting force monitoring, so as to solve the above-mentioned problems, break through the bottleneck of intelligent tool status, and meet the needs of the manufacturing industry for continuous detection of cutting force with lower cost and higher reliability.

[0005] To achieve the above objectives, the present invention provides the following solution: an intelligent tool holder based on a groove structure for cutting force monitoring, comprising:

[0006] A tool holder, wherein a plurality of groove groups are respectively provided on several side walls of the tool holder, the plurality of groove groups are located near the tool head, the plurality of groove groups are used to locally amplify the strain of the tool holder when subjected to force, the groove group includes a plurality of triangular grooves formed on the side walls of the tool holder, and the plurality of triangular grooves form a cross-shaped groove structure;

[0007] A plurality of thin-film strain gauges are respectively arranged corresponding to a plurality of groove groups, and the plurality of thin-film strain gauges are used to monitor the strain of the tool bar when it is subjected to force in different directions.

[0008] Preferably, the groove group includes eight sets of triangular grooves, the outlines of the eight sets of triangular grooves are all right-angled triangles, and the eight sets of triangular grooves are centrally symmetrically distributed to form a cross-shaped structure.

[0009] Preferably, two adjacent triangular grooves are separated by a partition beam.

[0010] Preferably, the length of the right-angled side of the triangular groove is 0% to 50% of the width of the tool bar, and the width of the partition beam is 0% to 20% of the width of the tool bar;

[0011] The depth of the triangular groove is 0% to 50% of the width of the tool holder.

[0012] Preferably, several of the thin-film strain gauges are respectively disposed on the outer wall of the knife bar near the groove assembly or on the partition beam.

[0013] Preferably, the thickness of the thin-film strain gauge is 400–1000 nm.

[0014] Preferably, the surface of the tool holder is covered with an alumina film, and the thin-film strain gauge is disposed on the alumina film.

[0015] Preferably, the surface of the thin-film strain gauge is covered with a protective layer.

[0016] Preferably, the surface of the protective layer is covered with a moisture-proof layer.

[0017] Compared with existing technologies, this invention has the following advantages and technical effects: The main function of the groove group is to locally amplify the strain at the groove group when the tool holder is subjected to force, assisting the thin-film strain gauge in measuring minute cutting forces and helping to improve measurement accuracy; the main function of the thin-film strain gauge is to monitor the strain at the groove group. Overall, this invention amplifies local strain while ensuring rigidity by machining several star-shaped groove structures near the tool tip, enabling the measurement of minute cutting forces and improving measurement accuracy. Simultaneously, by placing thin-film strain gauges in the star-shaped groove structures and applying them to the monitoring of cutting forces in machining processes, this invention offers advantages such as strong operability, simple process, and low cost. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only 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] Figure 1 This is a front view of the intelligent tool holder of the present invention;

[0020] Figure 2 This is a top view of the intelligent tool holder of the present invention;

[0021] Figure 3 This is a bottom view of the intelligent tool holder of the present invention;

[0022] Figure 4 This is a schematic diagram of the groove assembly of the present invention;

[0023] Figure 5 This is a flowchart illustrating the processing of the intelligent tool holder of the present invention;

[0024] Figure 6 This is a schematic diagram of the arrangement of a thin-film strain gauge according to the present invention;

[0025] Figure 7 This is a schematic diagram of the thin-film strain gauge structure of the present invention;

[0026] Among them, 1. Tool holder; 2. Groove assembly; 21. Triangular groove; 22. Separating beam; 3. Thin film strain gauge. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0029] Example 1:

[0030] Reference Figures 1-4 This invention provides an intelligent tool holder based on a groove structure for cutting force monitoring, comprising:

[0031] The tool holder 1 has several groove groups 2 on its side walls. The groove groups 2 are located near the tool head. The groove groups are used to locally amplify the strain of the tool holder 1 when it is under force. The groove group 2 includes several triangular grooves 21 opened on the side walls of the tool holder 1. The several triangular grooves 21 form a cross-shaped groove structure.

[0032] Several thin-film strain gauges 3 are respectively set with several groove groups 2. The thin-film strain gauges 3 are used to monitor the strain of the tool holder 1 when it is subjected to force in different directions.

[0033] The main function of the groove group 2 is to locally amplify the strain at the groove group 2 when the tool holder is subjected to force, assisting the thin-film strain gauge 3 in measuring minute cutting forces and helping to improve measurement accuracy. The main function of the thin-film strain gauge 3 is to monitor the strain at the groove group 2. Overall, this invention amplifies local strain while ensuring rigidity by machining several star-shaped groove structures near the tool tip, enabling the measurement of minute cutting forces and improving measurement accuracy. At the same time, by setting thin-film strain gauges in the star-shaped groove structures, the application of thin-film strain gauges in the monitoring of cutting forces in machining has the advantages of strong operability, simple process, and low cost.

[0034] Further optimization of the scheme: the groove group 2 includes eight sets of triangular grooves 21. The outlines of the eight sets of triangular grooves 21 are all right-angled triangles, and the eight sets of triangular grooves 21 are centrally symmetrically distributed to form a cross-shaped structure.

[0035] The scheme is further optimized by separating two adjacent triangular grooves 21 with a partition beam 22.

[0036] like Figure 4As shown, a set of right-angled sides of any triangular groove 21 is separated from the right-angled side of an adjacent triangular groove 21 by a partition beam 22. Simultaneously, the hypotenuse of this triangular groove 21 is separated from the hypotenuse of another adjacent triangular groove 21 by a partition beam 22, thus forming eight sets of partition beams 22. These eight sets of partition beams 22 intersect each other to form a star-shaped structure. While ensuring the tool holder 1 meets the required rigidity, the groove group 2 can amplify the strain of the tool holder 1 under stress, facilitating numerical monitoring by the thin-film strain gauge 3.

[0037] Further optimize the plan.

[0038] The length of the right-angled side of the triangular groove 21 (i.e., a shown in the figure) is 0% to 50% of the width of the tool bar 1, and the width of the partition beam 22 (i.e., b shown in the figure) is 0% to 20% of the width of the tool bar 1.

[0039] The depth of the triangular groove 21 is 0% to 50% of the width of the tool holder 1.

[0040] Further optimization of the scheme involves setting several thin-film strain gauges 3 on the outer wall of the tool holder 1 near the groove group 2 or on the partition beam 22.

[0041] Further optimization of the design resulted in a thickness of 400–1000 nm for the thin-film strain gauge 3.

[0042] The scheme was further optimized by covering the surface of the tool holder 1 with an aluminum oxide film, and the thin film strain gauge 3 was installed on the aluminum oxide film.

[0043] Further optimization of the design involved covering the surface of the thin-film strain gauge 3 with a protective layer.

[0044] To further optimize the design, an aluminum oxide film can be used as the protective layer.

[0045] The design was further optimized by covering the surface of the protective layer with a moisture-proof layer.

[0046] Example 2:

[0047] The above-mentioned method for fabricating a smart tool holder based on a groove structure for cutting force monitoring includes the following steps:

[0048] Tool holder structure design; Model the tool holder 1, set the groove group 2 with appropriate parameters at the appropriate position of the tool holder 1, and perform simulation analysis on the tool holder 1 to mark the points with small interference and large strain;

[0049] Mask fabrication; Based on the design of the thin film resistor, a corresponding mask is fabricated using processes such as laser cutting or metal etching for subsequent deposition;

[0050] Groove assembly machining; Groove assembly 2 is machined on tool holder 1;

[0051] Thin film strain gauge fabrication: The tool holder 1 is ground and polished, and then an alumina thin film is prepared on the surface of the tool holder 1 by electron beam evaporation. Then, a thin film strain gauge 3 is prepared on the alumina thin film by magnetron sputtering.

[0052] Detection and characterization of thin film strain gauges; the geometric parameters and resistance values ​​of the prepared thin film strain gauge 3 were measured, and then the thin film strain gauge was characterized.

[0053] Tool holder calibration: Connect the thin film strain gauge 3 to the Wheatstone bridge circuit, and apply different magnitudes of triaxial force to the tool holder 1 in sequence to calibrate the thin film strain gauge 3;

[0054] Tool holder encapsulation; a protective layer is prepared on the thin film strain gauge 3, and a moisture-proof adhesive is coated on its surface.

[0055] Specifically, such as Figure 5 As shown, the entire preparation process in this embodiment includes:

[0056] (1) Tool holder structure design: The tool holder 1 of the lathe tool is modeled, and the groove group 2 is set in a suitable position in the tool holder 1. The length of the right-angle side of the triangular groove 21, the width of the partition beam 22, and the groove depth are set. The stress of the tool holder 1 with this structure is simulated and analyzed in the finite element software. The rear end face of the tool holder 1 is fixed, and loads in three different directions (X, Y, and Z) are applied to the tool tip. The deformation of the tool tip is compared with that of the tool holder 1 without the window frame structure. If the difference in deformation is small, the points with small cross-interference and large strain at the groove group 2 are marked, and the distribution of the points is observed to design the corresponding thin film strain gauge 3. If the difference in deformation is large, the structural parameters and position of the groove group 2 can be adjusted, and the above work can be repeated.

[0057] Specifically, a groove structure is introduced on the surface of the tool holder 1 to achieve the functions of decoupling three-dimensional forces and amplifying strain. In the simulation, a lathe tool is selected, and the width and height of the tool holder 1 are 20mm×20mm. The rear surface of the tool holder is fixed, and forces of different magnitudes from 0 to 200N are applied at the tool tip to simulate the change of cutting force. The stress distribution on the surface of the tool holder and the displacement change of the tool tip are observed. The stress distribution is used to provide a basis for the arrangement of the thin-film strain gauge 3, and the tool tip displacement is used to observe the stiffness change of the tool holder 1 to avoid excessive stiffness changes from adversely affecting the machining error. In this simulation embodiment, the length of the right-angled side of the triangular groove 21 is 7.5mm, the depth is 2mm, and the axial distance between the side closest to the tool tip and the tool tip is 25.43mm. Simulation analysis shows that, compared with before grooving, the stress near the groove increases by 20%-200% after grooving, while the displacement at the tool tip only increases by 4.3%. Furthermore, this structure can achieve decoupling of three-dimensional forces with an error of no more than 20%, and the effect of the three-dimensional forces satisfies the linear superposition characteristic. Subsequently, the cutting forces in the three directions can be solved by combining the measurement results, which can meet the relevant measurement requirements.

[0058] (2) Mask preparation: Based on the design of the thin film resistor, the corresponding mask is prepared by laser cutting or metal etching and other processes for subsequent deposition.

[0059] (3) Groove structure processing: The corresponding groove group 2 is processed on the tool holder 1 by milling or other methods.

[0060] (4) Preparation of thin film strain gauge: The surface of the tool holder 1 is polished until it is smooth and free of scratches. Then, the tool holder 1 is ultrasonically cleaned with acetone, anhydrous ethanol and ultrapure water in sequence. Alumina thin film is prepared by electron beam evaporation. During the preparation process, the film growth rate is controlled at 0.4 to 0.6 Å and the film thickness is controlled at 1 to 3 μm. Then, the surface is cleaned again with acetone, anhydrous ethanol and ultrapure water. Using magnetron sputtering, a thin film strain gauge with a thickness of 400 to 1000 nm is prepared by magnetron sputtering with chromium-nickel alloy as the material.

[0061] In this embodiment, a 2 μm alumina film was prepared at a growth rate of 0.5 A / s under a vacuum of 3 × 10⁻³ Pa. Subsequently, a thin-film strain gauge with a thickness of 600–800 nm was prepared by magnetron sputtering using a nickel alloy as the material under a vacuum of 0.6 Pa and a power of 80 W.

[0062] Specifically, six sets of grooves 2 are formed on the surface of the tool holder 1, and six thin-film strain gauges 3 are arranged near three of the groove sets 2. Two strain gauges are arranged on the surface of each groove set 2 (see details). Figures 1-3 (As shown). This thin-film strain gauge 3 consists of two sheet resistors with a side length of 1mm and three resistance sections. Its specific dimensions are as follows: Figure 7 As shown in the figure, h = 1.00, i = 0.12, j = 2.10, k = 0.20 (unit: millimeters).

[0063] During the design phase, based on simulation results, points near the groove group with relatively large strain and good triaxial force decoupling (e.g., large stress only when the cutting force acts in the X direction, and smaller stress when the force acts in the other two directions) are selected for strain gauge arrangement. The strain gauges can be arranged in the partition beam 22 or in other parts around the groove group 2. This embodiment demonstrates an arrangement of thin-film strain gauges 3 as follows: Figure 6 As shown in the figure, a = 31.73, b = 37.73, c = 24.73, d = 30.73, e = 25.20, f = 31.73, g = 1.18 (unit: millimeters).

[0064] (5) Detection and characterization of thin film strain gauges: The geometric parameters and resistance values ​​of the prepared thin film strain gauge 3 were measured and compared with the theoretical values. Under the condition that the difference between the two is not significant, the thin film strain gauge was further characterized by instruments such as SEM.

[0065] (6) Calibration and packaging of the intelligent tool holder: After characterization, the thin film strain gauge 3 was connected to the Wheatstone bridge circuit using a bonding machine, and triaxial forces of different magnitudes were applied to the tool tip in sequence to calibrate the thin film strain gauge. At the same time, a 2µm thick layer of aluminum oxide was prepared on the thin film strain gauge as a protective layer, and a layer of moisture-proof adhesive was coated on its surface to prevent the coolant from affecting the performance of the strain gauge.

[0066] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0067] 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. An intelligent tool bar for cutting force monitoring based on a groove structure, characterized by , comprising: A tool bar (1), a plurality of side walls of the tool bar (1) are respectively provided with groove groups (2), a plurality of groove groups (2) are arranged near the tool bit position, a plurality of groove groups are used to locally enlarge the strain of the tool bar (1) under stress, the groove group (2) comprises a plurality of triangular grooves (21) opened on the side wall of the tool bar (1), a plurality of triangular grooves (21) form a rice-shaped groove structure; A plurality of thin film strain gauges (3) are arranged corresponding to a plurality of groove groups (2), a plurality of thin film strain gauges (3) are used to monitor the strain of the tool bar (1) under different direction stress; The preparation method of the above-mentioned intelligent tool bar for cutting force monitoring based on groove structure comprises: Tool bar structure design; modeling the tool bar (1), setting the groove group (2) with appropriate parameters at the appropriate position of the tool bar (1), and simulating and analyzing the tool bar (1), and marking the points with small interference and large strain; Mask preparation; according to the design of thin film resistance, the corresponding mask is prepared for subsequent deposition; Groove group processing; the groove group (2) is processed on the tool bar (1); Thin film strain gauge preparation; the tool bar (1) is polished and polished, then the aluminum oxide film is prepared on the surface of the tool bar (1) by electron beam evaporation, and then the thin film strain gauge (3) is prepared on the basis of the aluminum oxide film by magnetron sputtering; Detection and characterization of thin film strain gauge; measure the geometric parameters and resistance value of the prepared thin film strain gauge (3), and then characterize the thin film strain gauge; Tool bar calibration; connect the thin film strain gauge (3) to the Wheatstone circuit bridge, and sequentially apply different sizes of three-way force to the tool bar (1) to calibrate the thin film strain gauge (3); Tool bar packaging; a protective layer is prepared on the thin film strain gauge (3), and a layer of moisture-proof glue is coated on the surface.

2. The smart tool bar based on the groove structure for cutting force monitoring according to claim 1, characterized in that: The groove group (2) comprises eight groups of triangular grooves (21), the profiles of the eight groups of triangular grooves (21) are all right-angled triangles, and the eight groups of triangular grooves (21) are centrally symmetrically distributed to form a rice-shaped structure.

3. The smart tool bar based on the groove structure for cutting force monitoring according to claim 2, characterized in that: Two adjacent triangular grooves (21) are separated by a partition beam (22).

4. The smart tool bar based on the groove structure for cutting force monitoring according to claim 3, characterized in that: The length of the right angle side of the triangular groove (21) is 0%-50% of the width of the tool bar (1), and the width of the partition beam (22) is 0%-20% of the width of the tool bar (1). The depth of the triangular groove (21) is 0%-50% of the width of the tool bar (1).

5. The smart tool bar based on the groove structure for cutting force monitoring according to claim 3, characterized in that: A plurality of thin film strain gauges (3) are arranged on the outer wall of the tool bar (1) near the groove group (2) or on the partition beam (22).

6. The smart tool bar based on the groove structure for cutting force monitoring according to claim 3, characterized in that: The thickness of the thin film strain gauge (3) is 400-1000nm.

7. The smart tool bar based on the groove structure for cutting force monitoring according to claim 3, characterized in that: The surface of the tool bar (1) is covered with an aluminum oxide film, and the thin film strain gauge (3) is arranged on the aluminum oxide film.

8. The smart tool bar based on the groove structure for cutting force monitoring according to claim 3, characterized in that: The surface of the thin film strain gauge (3) is covered with a protective layer.

9. The smart tool bar based on the groove structure for cutting force monitoring according to claim 8, characterized in that: The surface of the protective layer is covered with a moisture-proof layer.

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