A tool stress temperature detection device and a preparation method thereof

Abstract

The application provides a tool stress temperature detection device and detection method, the detection device includes a tool holder mechanism, a tool head mechanism and a detection mechanism, the tool holder mechanism includes a tool holder and a limiting convex provided on the head of the tool holder; the tool head mechanism includes a tool head and a limiting hole provided on the tool head, the tool head is fixed on the tool holder by screwing, the hole shape of the limiting hole matches the outer peripheral shape of the limiting convex; the detection mechanism includes a force and heat sensitive element, the force and heat sensitive element is integrally arranged on the limiting convex. The application integrates the force and heat sensitive element on the limiting convex, and the limiting hole is provided on the tool head. During the operation of the tool, the stress is concentrated at the limiting hole and is transmitted to the force and heat sensitive element, and the temperature is heat-conducted to the force and heat sensitive element, so that the online monitoring of the stress and temperature of the tool is realized, the detection result is more sensitive and accurate, the force and heat sensitive element is integrally arranged on the tool holder, the tool holder does not need to be replaced when the worn tool head is replaced, and the stable and efficient operation of the numerical control machine tool is effectively ensured.

Description

Technical Field

[0001] This application relates to the field of machining technology, specifically to a tool stress temperature detection device and its preparation method. Background Technology

[0002] In recent years, with the continuous development of CNC technology, industrial intelligence, and automation, the efficiency, quality, and precision of machining have significantly improved. As a crucial component of machine tool processing, the condition of cutting tools has a significant impact on the machining accuracy and workpiece surface quality. During machining, cutting tools experience significant impact, friction, and high temperatures due to direct contact with the workpiece, leading to breakage—a common and unavoidable phenomenon. Failure to stop the machine and replace the tool in time will result in workpiece scrap, and in severe cases, damage to the machine tool. In CNC machine tool processing, the constantly changing cutting force between the tool and workpiece accounts for 20% of machine tool downtime caused by tool breakage. Tool breakage negatively impacts machining efficiency and quality, leading to reduced workpiece machining accuracy, increased surface roughness, higher cutting temperatures, cutting vibration, increased cutting load, and insufficient depth of cut. Tool breakage is the result of the combined effects of mechanical and thermal stresses within the tool wedge. The mechanical stress state and temperature of the tool play a significant role in tool breakage.

[0003] Tool wear detection can be achieved through cutting force signals, acoustic emission signals, current signals, and image processing. Image processing methods are unsuitable due to the influence of debris in the cutting environment; current signals convert the tool's stress state into current measurement, which is greatly affected by the operating voltage; acoustic emission signals cannot eliminate the effects of chip breakage, and their high-frequency signal stability is poor; acoustic emission and current signals both reflect tool breakage signals, while cutting force is the most direct signal reflecting the amount of tool wear, offering higher accuracy. However, force gauges are expensive, and their installation places high demands on the machine tool structure, sometimes even preventing installation due to interference with machining. Therefore, a low-cost, minimally impactful, and easily installable mechanical sensor is needed to read the mechanical changes in the tool. Aluminum nitride FBAR piezoelectric resonant sensors are compact and well-suited for mechanical sensing, but their resonant frequency is affected by the coupling of temperature and pressure, making it difficult to accurately read stress values.

[0004] Therefore, it is of great significance to adopt a new approach to avoid the problems of existing tool stress detection and to measure tool stress and temperature using a resonant sensor with a smaller size and a higher quality factor at a higher resonant frequency. Summary of the Invention

[0005] This application provides a tool stress and temperature detection device, which can solve the technical problems of existing tool wear detection devices, such as high cost, significant impact on tool structure, inconvenience in installing mechanical sensors, and inaccurate detection results.

[0006] In a first aspect, this application provides a tool stress-temperature detection device, comprising:

[0007] A tool holder mechanism includes a tool holder and a limiting protrusion protruding from the tool holder;

[0008] A cutting head mechanism includes a cutting head and a limiting hole provided on the cutting head. The cutting head is screwed and fixed to the cutting shank. The shape of the limiting hole matches the outer peripheral shape of the limiting protrusion.

[0009] The detection mechanism includes a force-thermal sensitive element, which is integrated onto the limiting protrusion.

[0010] In conjunction with the first aspect, in one embodiment, the number of limiting holes is two, and the number of limiting protrusions is correspondingly set to two. Both limiting holes are rectangular holes. The length direction of one limiting hole is set along the length direction of the tool holder, and the length direction of the other limiting hole is set perpendicular to the length direction of the tool holder.

[0011] In conjunction with the first aspect, in one embodiment, the force-thermal sensitive element is a Lamb wave resonator.

[0012] In conjunction with the first aspect, in one embodiment, the Lamb wave resonator has a multilayer structure, consisting of a substrate and a piezoelectric layer from bottom to top. The bottom surface of the substrate is fixed to the tool holder, and a groove is formed on the top surface of the substrate. The groove and the piezoelectric layer enclose each other to form the cavity. The top surface of the piezoelectric layer has multiple grooves, and an upper electrode is provided on the top of the multiple grooves.

[0013] In conjunction with the first aspect, in one embodiment, the Lamb wave resonator is covered with a metal protective layer, the metal protective layer being made of a thermally conductive metal.

[0014] In conjunction with the first aspect, in one embodiment, when the limiting protrusion engages within the limiting hole, the cavity is located within the limiting hole.

[0015] In conjunction with the first aspect, in one embodiment, the piezoelectric layer is PZT (lead zirconate titanate piezoelectric ceramics), AlN, or LiNbO3.

[0016] Secondly, this application provides a method for preparing the tool stress temperature detection device as described above, comprising the following steps:

[0017] A limiting hole is made on the cutter head;

[0018] A limiting protrusion is machined at the head of the tool holder, and a force and heat sensitive element is integrated and disposed on the limiting protrusion;

[0019] The cutting head is pre-installed on the cutting handle by fitting the limiting hole to the outer periphery of the limiting protrusion;

[0020] The cutting head and the tool holder are further screwed together to complete the installation and fixation of the cutting head on the tool holder, thus obtaining the tool stress and temperature detection device provided in this application.

[0021] In conjunction with the second aspect, in one embodiment, machining a limiting protrusion on the tool holder and integrating a Lamb wave device with a cavity onto the limiting protrusion includes:

[0022] A groove is formed on the top surface of the substrate, and the groove is filled with a sacrificial material;

[0023] A piezoelectric layer is fabricated on top of the substrate;

[0024] An upper electrode is fabricated above the piezoelectric layer;

[0025] Patterned top electrode;

[0026] A trench structure is etched on the piezoelectric layer using an upper electrode mask;

[0027] Then, a release hole is etched from the groove structure to the groove.

[0028] Etching material is injected into the groove from the release hole to etch the sacrificial material in the groove.

[0029] The beneficial effects of the technical solutions provided in this application include at least the following:

[0030] This application integrates a force-thermal sensing element onto the limiting protrusion of the tool holder and opens a limiting hole on the tool tip. During tool operation, the stress on the tool tip is concentrated at the limiting hole and transmitted to the force-thermal sensing element on the limiting protrusion. The resonator frequency of the force-thermal sensing element is converted into a preload output, and the temperature of the tool tip is conducted to the limiting protrusion. The stress and temperature changes of the tool are respectively converted into changes in the force-thermal sensing element and changes in the material, realizing online monitoring of the stress and temperature of the tool. The detection results are more sensitive and accurate.

[0031] By integrating the force and heat sensing element onto the tool holder, when replacing a worn tool head, there is no need to replace the tool holder or reinstall the force and heat sensing element, making the structure durable.

[0032] This invention provides a tool stress and temperature detection device with high sensitivity, accurate detection, and durability for tool wear detection, effectively ensuring the stable and efficient operation of CNC machine tools. Attached Figure Description

[0033] Figure 1 This is a partial structural schematic diagram of the tool stress and temperature detection device provided in the embodiments of this application;

[0034] Figure 2 A schematic diagram of the detection principle of the tool stress and temperature detection device provided in the embodiments of this application;

[0035] Figure 3 This is a schematic diagram of the Lamb wave structure provided in an embodiment of this application;

[0036] Figure 4 Frequency drift diagram of the resonator of the tool stress and temperature detection device provided in this application embodiment under environmental changes.

[0037] In the figure, 10 is the bolt; 20 is the cutting head; 21 is the bolt through hole; 22 is the limiting hole; 30 is the cutting handle; 31 is the Lamb wave resonator; 32 is the nut; 41 is the cavity; 42 is the piezoelectric layer; 43 is the groove; and 44 is the upper electrode. Detailed Implementation

[0038] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0039] In the description of the embodiments of this application, terms such as "exemplary," "for example," or "for instance" are used to indicate examples, illustrations, or explanations. Any embodiment or design described as "exemplary," "for example," or "for instance" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of terms such as "exemplary," "for example," or "for instance" is intended to present the relevant concepts in a concrete manner.

[0040] In the description of the embodiments of this application, unless otherwise stated, " / " means "or". For example, A / B can mean A or B. The "and / or" in the text is merely a description of the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist simultaneously, and B exists alone. In addition, in the description of the embodiments of this application, "multiple" means two or more.

[0041] In some processes described in the embodiments of this application, multiple operations or steps are included in a specific order. However, it should be understood that these operations or steps may not be executed in the order they appear in the embodiments of this application, or they may be executed in parallel. The sequence number of the operation is only used to distinguish different operations, and the sequence number itself does not represent any execution order. In addition, these processes may include more or fewer operations, and these operations or steps may be executed sequentially or in parallel, and these operations or steps may be combined.

[0042] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0043] Firstly, please refer to Figure 1 This application provides a tool stress and temperature detection device, including a tool holder mechanism, a tool head mechanism, and a detection mechanism. The tool holder mechanism includes a tool holder 30 and a limiting protrusion protruding from the tool holder 30. The tool head mechanism includes a tool head 20 and a limiting hole 22 provided on the tool head 20. The tool head 20 is screwed and fixed to the tool holder 30. The shape of the limiting hole 22 matches the outer peripheral shape of the limiting protrusion. The tool head 20 is locked onto the outer peripheral of the limiting protrusion through the limiting hole 22 to achieve a limiting and fixing function. Combined with the screw connection, the tool head 20 is firmly fixed to the head of the tool holder 30. The detection mechanism includes a force and heat sensitive element, which is integrated on the limiting protrusion.

[0044] This application integrates a force-thermal sensing element onto the limiting protrusion of the tool holder 30 and provides a limiting hole 22 on the tool head 20. During tool operation, stress in the tool head 20 concentrates at the limiting hole 22 and is transmitted to the force-thermal sensing element on the limiting protrusion. The resonator frequency of the force-thermal sensing element is converted into a preload output, and the temperature of the tool head 20 is conducted to the limiting protrusion. This converts tool stress and temperature changes into changes in the force-thermal sensing element and material changes, respectively, enabling online monitoring of tool stress and temperature. The detection results are more sensitive and accurate. By integrating the force-thermal sensing element onto the tool holder 30, when replacing a worn tool head 20, there is no need to replace the tool holder 30 or reinstall the force-thermal sensing element, resulting in a durable structure. This provides a tool stress and temperature detection device with high sensitivity, accuracy, and durability for tool wear detection, effectively ensuring the stable and efficient operation of CNC machine tools.

[0045] In one embodiment, there are two limiting holes 22 and two corresponding limiting protrusions. Both limiting holes 22 are rectangular holes with a length much greater than their width. The length direction of one limiting hole 22 is along the length direction of the tool holder 30, and the length direction of the other limiting hole 22 is perpendicular to the length direction of the tool holder 30. Here, the length extension direction of the tool holder 30 is defined as the X-axis. The length direction of one limiting hole 22 is along the X-axis, and the length direction of the other limiting hole 22 is along the Y-axis. During the cutting process, the cutting stress of the tool head 20, which is screwed to the head of the tool holder 30, is concentrated at the two limiting holes 22 of the tool head 20. The stress is then transmitted to the limiting protrusions that contact the edges of the two limiting holes 22, and finally to the force and heat sensitive element integrated on the limiting protrusions, thereby realizing the sensing and detection of the cutting stress during the cutting process. More specifically, the edge of the limiting hole 22 in the X direction transmits the X-axis component stress of the cutting tool head 20 to the force-heat sensitive element, and the edge of the limiting hole 22 in the Y direction transmits the Y-axis component stress of the cutting tool head 20 to the force-heat sensitive element. It can be understood that since the limiting hole 22 is tightly fitted on the outer periphery of the limiting protrusion, the temperature on the cutting tool head 20 can be conducted to the limiting protrusion during the cutting process, and finally to the force-heat sensitive element. Thus, the force-heat sensitive element can sense and detect the stress and temperature during the cutting process of the cutting tool head 20.

[0046] In a preferred embodiment, when the limiting hole 22 matches the outer periphery of the corresponding limiting protrusion, the force-heat sensitive element is located in the middle of the limiting hole 22, specifically, in the middle of the height direction of the corresponding limiting hole 22; preferably, it is located in the middle of both the height direction and the diameter direction of the corresponding limiting hole 22, so as to realize the accurate sensing and detection of the cutting stress and cutting temperature of the tool head 20 that is transmitted to the cavity of the limiting hole 22 by force and heat.

[0047] In one embodiment, both the head of the cutter head 20 and the handle 30 are provided with threaded holes, and the bolt 10 passes through the two threaded holes and is fastened to the handle 30 with the nut 32.

[0048] In a preferred embodiment, to improve the accuracy and sensitivity of tool temperature sensing and detection, and to achieve physical protection of the force and heat sensitive element during tool cutting, the limiting convex surface is covered with a metal protective layer. The metal protective layer is made of a metal material with good thermal conductivity. Preferably, it is made of a material with good thermal conductivity and rigidity, in order to achieve good heat conduction effect and physical protection effect in the cutting environment.

[0049] In a preferred embodiment, the force-heat sensitive element has a cavity 41 to achieve highly sensitive and accurate sensing and detection of the cutting stress and temperature of the cutter head 20 transmitted to the cavity of the limiting hole 22 by force and heat.

[0050] In a more specific embodiment, such as Figure 2 As shown, the force-thermal sensing element is a Lamb wave resonator 31, with a cavity 41 in its middle. Using the Lamb wave resonator 31 with cavity 41, the changes in tool stress and temperature are respectively converted into changes in the structure and material of the Lamb wave resonator 31, causing a frequency shift between the S0 and S1 modes of the Lamb wave resonator 31. By measuring these two frequency shifts, the magnitude of the force on the tested tool and the corresponding temperature change are obtained.

[0051] In a more specific embodiment, such as Figure 3 As shown, the Lamb wave resonator 31 has a multi-layer structure, consisting of a substrate and a piezoelectric layer 42 from bottom to top. The bottom surface of the substrate is fixed to the head of the knife handle 30. More specifically, a groove is formed on the top surface of the substrate, and the groove and the piezoelectric layer 42 enclose the cavity 41. Multiple grooves 43 are formed on the top surface of the piezoelectric layer 42, and an upper electrode 44 is provided on the top of the multiple grooves 43.

[0052] The following is a specific embodiment of integrating a Lamb wave resonator 31 into a limiting cam to detect the stress and temperature of the cutting tool:

[0053] Example 1

[0054] A Lamb wave resonator 31 for detecting the working temperature and stress of machine tool cutting tools includes, from bottom to top, a substrate, a cavity 41, a piezoelectric layer 42, a piezoelectric layer 42 trench 43, and an upper electrode 44. For example... Figure 2 As shown, when a tool suddenly develops a defect during operation, causing a temperature rise and abnormal stress, the resonant frequency of the Lamb wave resonator 31 changes linearly with the temperature. This change can be transmitted to the limiting Lamb wave resonator 31, and the change can be read from the resonant frequency change, thereby achieving tool detection.

[0055] Example 2

[0056] A Lamb wave resonator 31 was fabricated on a Si substrate using AlN piezoelectric material and a Mo top electrode 44. The resonant frequencies of the S0 mode of the Lamb wave resonator 31 were measured at different temperatures. Figure 4As shown, the effect of temperature increase on sound velocity is significantly reflected in the resonant frequency. Calibrating the resonant frequency allows for temperature measurement, with temperature values ​​read from frequency changes. Stress can also be obtained through resonant frequency changes. The resonator structure of this application uses two excited modes to read stress and temperature, respectively, fulfilling the requirements for tool inspection.

[0057] Secondly, this application provides a method for preparing a tool stress temperature detection device, comprising the following steps:

[0058] Step S1: Make a limiting hole 22 on the cutter head 20;

[0059] Step S2: Machining a limiting protrusion on the tool holder 30, and integrating a force and heat sensitive element with a cavity 41 onto the limiting protrusion;

[0060] Step S3: The cutting head 20 is pre-installed on the cutting handle 30 by fitting it to the outer periphery of the limiting protrusion through the limiting hole 22;

[0061] Step S4: Further screw the cutter head 20 and the cutter holder 30 together to complete the installation and fixation of the cutter head 20 on the cutter holder 30.

[0062] In one embodiment, step S2, machining a limiting protrusion on the tool holder 30 and integrating a Lamb wave device with a cavity 41 onto the limiting protrusion, includes:

[0063] Step S21: A groove is formed on the top surface of the substrate, and the groove is filled with a sacrificial material; more specifically, the sacrificial material is SiO2;

[0064] Step S22: Prepare a piezoelectric layer 42 on the substrate;

[0065] Step S23: Fabricate an upper electrode 44 above the piezoelectric layer 42;

[0066] Step S24: Pattern the upper electrode 44;

[0067] Step S25: Use the upper electrode 44 mask to etch the trench 43 structure on the piezoelectric layer 42;

[0068] Step S26: Then etch a release hole from the groove 43 structure to the groove.

[0069] Step S27: Inject etching material - hydrofluoric acid into the groove through the release hole to etch the sacrificial material in the groove and make way for cavity 41.

[0070] In the description of this application, it should be noted that the terms "upper," "lower," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not 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 application. Unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two elements. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0071] It should be noted that in this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0072] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A tool stress temperature detection device, characterized in that, include: A tool holder mechanism includes a tool holder and a limiting protrusion protruding from the tool holder; A cutting head mechanism includes a cutting head and a limiting hole formed on the cutting head. The cutting head is screwed and fixed to the cutting shank. The shape of the limiting hole matches the outer peripheral shape of the limiting protrusion. The detection mechanism includes a Lamb wave resonator, which is integrated onto the limiting protrusion. The number of limiting holes is two, and the number of limiting protrusions is set to two accordingly. Both limiting holes are rectangular holes. The length direction of one limiting hole is set along the length direction of the tool holder, and the length direction of the other limiting hole is set perpendicular to the length direction of the tool holder. The Lamb wave resonator has a multilayer structure, consisting of a substrate and a piezoelectric layer from bottom to top. The bottom surface of the substrate is fixed to the tool holder, and a groove is formed on the top surface of the substrate. The groove and the piezoelectric layer enclose a cavity. Multiple grooves are formed on the top surface of the piezoelectric layer, and an upper electrode is provided on the top of the multiple grooves. The Lamb wave resonator is covered with a metal protective layer, which is made of thermally conductive metal. When the limiting protrusion engages with the limiting hole, the cavity is located within the limiting hole; The piezoelectric layer is PZT, AlN, or LiNbO3.

2. The tool stress and temperature detection device as described in claim 1, characterized in that, Both the head and the handle of the cutter are provided with threaded holes. Bolts pass through the two threaded holes and are fastened to the handle with nuts.

3. A method for preparing a tool stress temperature detection device as described in claim 1 or 2, characterized in that, Includes the following steps: A limiting hole is made on the cutter head; A limiting protrusion is machined on the tool holder, and a Lamb wave resonator is integrated and disposed on the limiting protrusion. The cutting head is pre-installed on the cutting handle by fitting the limiting hole to the outer periphery of the limiting protrusion; The cutting head and the tool holder are further screwed together to fix them in place, thus completing the installation and fixation of the cutting head on the tool holder and producing a tool stress and temperature detection device.

4. The preparation method according to claim 3, characterized in that, The process of machining a limiting protrusion on the tool holder and integrating a Lamb wave resonator with a cavity onto the limiting protrusion includes: A groove is formed on the top surface of the substrate, and the groove is filled with a sacrificial material; A piezoelectric layer is fabricated on top of the substrate; An upper electrode is fabricated above the piezoelectric layer; Patterned top electrode; A trench structure is etched on the piezoelectric layer using an upper electrode mask; Then, etch from the groove structure all the way to the release hole in the groove; Etching material is injected into the groove from the release hole to etch the sacrificial material in the groove.

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