Apparatus and method for grinding a fixed depth metallographic specimen

Abstract

The application provides a device and method for grinding a fixed-depth metallographic sample, and relates to the field of metal material metallographic sample preparation. The device comprises a first conductive unit embedded in a metallographic sample embedding material, a clamp for clamping the embedded metallographic sample, a second conductive unit electrically connected to the first conductive unit, and a warning unit. The grinding surface of the embedded metallographic sample is a working surface, the end of the first conductive unit near the working surface in the embedding material is a first end, the distance between the first end and the working surface in the grinding depth direction is not more than the fixed depth to be ground. The grinding depth direction is the up-down direction, the height of the highest point of the conductive loop formed by the first end, the second conductive unit and the warning unit above the first end from the working surface is equal to the fixed depth, and when the working surface is ground to the disconnection of the conductive loop, the warning unit broadcasts a warning signal, thereby accurately controlling the grinding of the metallographic sample to the fixed depth. The application fully solves the problem that the current metallographic sample cannot be accurately ground to the fixed depth.

Description

Technical Field

[0001] This invention relates to the field of metallographic sample preparation technology, specifically to an apparatus and method for grinding metallographic samples to a fixed depth. Background Technology

[0002] Current metallographic sample preparation methods often face difficulties in precisely controlling the grinding depth when grinding samples of target thickness. Traditional metallographic sample preparation processes rely heavily on the operator's experience and operational precision. Each sample preparation cycle requires the operator to subjectively adjust the grinding force and time, and perform multiple thickness measurements to assess the grinding progress. This manual approach is not only inefficient but also limited by human factors, making it difficult to achieve consistent and accurate depth control standards. While some existing equipment allows for setting the grinding depth of metallographic samples—automatic grinding equipment—these adjustments are typically controlled with an accuracy of 10 μm or higher. This low precision, limited selection range, and high equipment cost hinder large-scale adoption.

[0003] The aforementioned manual grinding control schemes or equipment-controlled grinding depth schemes struggle to strictly limit the grinding depth within an ideal range. This directly leads to the possibility of over-grinding or insufficient grinding, making it difficult to precisely focus on specific depths within the material. Consequently, this affects in-depth analysis of the relationship between the material's microstructure and properties, resulting in low accuracy of test results. Therefore, how to accurately control the grinding depth at low cost has become an urgent technical problem to be solved. Summary of the Invention

[0004] The purpose of this invention is to provide an apparatus and method for grinding metallographic samples at a fixed depth. By synchronously embedding a sensing element and the metallographic sample at the target position, the metallographic sample outputs a prompt signal when it reaches the target position, thereby achieving precise control of the grinding depth.

[0005] To achieve the above objectives, the present invention proposes the following technical solution:

[0006] In the first aspect, an apparatus for grinding metallographic samples at a fixed depth is proposed, comprising a clamp, a first conductive unit, a second conductive unit, and a warning unit;

[0007] The first conductive unit is embedded in the mounting material of the embedded metallographic sample; the grinding surface of the embedded metallographic sample is defined as the working surface, and the end of the first conductive unit in the mounting material near the working surface is defined as the first end. Then, the distance between the first end and the working surface along the grinding depth direction of the embedded metallographic sample does not exceed the fixed depth to be ground of the embedded metallographic sample.

[0008] The fixture is used to hold the inlaid metallographic sample. One end of the second conductive unit is electrically connected to the first conductive unit and the other end is connected to the warning unit. The first conductive unit, the second conductive unit, and the warning unit in the inlaid metallographic sample to be ground form a conductive circuit.

[0009] The grinding depth direction of the mounted metallographic specimen is defined as the up-down direction, and the working surface is the bottom surface of the mounted metallographic specimen. The bottom surface is horizontal, and the height of the highest point of the conductive circuit formed by the first end of the first conductive unit, the second conductive unit, and the warning unit from the bottom surface is equal to the fixed grinding depth of the mounted metallographic specimen. Then, when the working surface of the mounted metallographic specimen is ground along the up-down direction until the conductive circuit is broken, the warning unit broadcasts a warning signal, and the metallographic specimen is ground to the fixed depth.

[0010] Furthermore, the first conductive unit is configured as a metal filament, and the two ends of the metal filament in the length direction form two conductive sites at intervals on the upper bottom surface of the inlaid metallographic sample.

[0011] Any two points on the metal filament at different positions do not contact each other, and its first end is arranged around the metallographic sample within the inlay material, with the metal filament and the metallographic sample being spaced apart.

[0012] Furthermore, the second conductive unit includes a positive conductive post, a negative conductive post, and a wire; the positive and negative conductive posts are respectively fixed on the fixture, with one end near the fixture connected to two conductive positions on the bottom surface of the metallographic sample after it is embedded inside the fixture, and the other end away from the fixture connected to the warning unit by the wire.

[0013] Furthermore, the upper and lower surfaces of the fixture are horizontal in the vertical direction, and the fixture is configured as a cavity structure with the lower surface open from the lower surface upward; the metallographic sample after mounting is fixed in the cavity structure, and the lower surface of the metallographic sample after mounting is parallel to and protrudes downward from the lower surface of the fixture in the cavity structure.

[0014] Furthermore, the shape and size of the inlaid metallographic sample are adapted to be installed in the cavity structure of the fixture.

[0015] Furthermore, the outer wall of the cavity structure of the fixture is uniformly and symmetrically provided with several fixing parts, which penetrate the outer wall of the cavity structure and abut against the outer wall of the inlaid metallographic sample.

[0016] Furthermore, the first end of the first conductive unit surrounds the metallographic sample at the same height within the insert.

[0017] Furthermore, the bottom of the fixture is provided with two through holes, the positions of which correspond to the positions of two conductive positions on the bottom surface of the metallographic sample after it is embedded inside the fixture. The positive and negative conductive posts are connected to the conductive positions through the two through holes.

[0018] Secondly, a method for grinding metallographic specimens at a fixed depth is proposed, comprising: simultaneously embedding a sensing element when the metallographic specimen of the target size is mounted, wherein the sensing height of the sensing element is set at the fixed depth position of the metallographic specimen to be ground; wherein the sensing element is electrically or signalally connected to an alarm unit, and the alarm unit is used to issue an alarm when the sensing element is open-circuited or the signal is interrupted.

[0019] The grinding process of the metallographic sample is monitored. The metallographic sample and the sensing element are ground synchronously. When the metallographic sample is ground to the sensing height of the sensing element, the warning unit electrically or signalally connected to the sensing element broadcasts a warning signal.

[0020] Thirdly, a method for grinding metallographic specimens at a fixed depth is proposed. This method uses the aforementioned apparatus for grinding metallographic specimens at a fixed depth and includes the following steps:

[0021] 1) Obtain a sample to be ground of a preset size;

[0022] 2) After the sample to be ground and the first conductive unit are arranged in the mounting machine according to the preset position requirements, the mounting material is added to mount the sample to be ground to obtain the mounted metallographic sample.

[0023] 3) Place the inlaid metallographic sample in the fixture and fix it so that the first conductive unit, the second conductive unit and the warning unit are electrically connected;

[0024] 4) Grind the inlaid metallographic sample held by the fixture along the up and down direction until the warning unit issues a warning, indicating that the highest point of the conductive circuit formed by the first end of the first conductive unit, the second conductive unit, and the warning unit in the inlaid metallographic sample has been ground away. Stop grinding and obtain a metallographic sample with a fixed grinding depth.

[0025] As can be seen from the above technical solutions, the technical solutions of the present invention have achieved the following beneficial effects:

[0026] This invention discloses an apparatus and method for grinding metallographic specimens to a fixed depth, which solves the problem that current metallographic sample preparation methods cannot accurately grind to a fixed depth. The apparatus includes a first conductive unit embedded in the metallographic specimen mounting material, a clamp for holding the mounted metallographic specimen, and a second conductive unit and an alarm unit electrically connected to the first conductive unit. The grinding surface of the mounted metallographic specimen is defined as the working surface, and the end of the first conductive unit in the mounting material near the working surface is defined as the first end. The distance between the first end and the working surface along the grinding depth direction of the metallographic specimen does not exceed the fixed depth to be ground. The grinding depth direction of the mounted metallographic specimen is defined as the up-down direction. The height of the highest point of the conductive circuit formed by the first end, the second conductive unit, and the alarm unit from the working surface is equal to the fixed depth. When the working surface is ground in the up-down direction until the conductive circuit is broken, the alarm unit broadcasts an alarm signal, accurately controlling the grinding of the metallographic specimen to the fixed depth. This apparatus has a simple structure and is highly efficient in application.

[0027] This invention achieves fixed-depth grinding of the sample by placing conductive units near the metallographic sample during the mounting process, extending into the mounting material. After mounting, the sample is placed in a fixture for grinding. When the desired depth is reached, the conductive circuit formed by the conductive units is broken, triggering a warning and stopping the grinding process. Compared with existing technologies, this invention transforms the problem of inaccurate adjustment and control of grinding depth into a warning signal change that is visually apparent to the user, thereby precisely controlling the fixed grinding depth. This method can be applied to fixed-depth grinding of different samples, offering wide applicability and low cost.

[0028] It should be understood that all combinations of the foregoing concepts and the additional concepts described in more detail below can be considered part of the inventive subject matter of this disclosure, provided that such concepts do not contradict each other.

[0029] The foregoing and other aspects, embodiments, and features of the teachings of the present invention will be more fully understood from the following description in conjunction with the accompanying drawings. Other additional aspects of the invention, such as features and / or beneficial effects of exemplary embodiments, will become apparent from the following description or may be learned through practice of specific embodiments according to the teachings of the present invention. Attached Figure Description

[0030] The accompanying drawings are not drawn to scale. In the drawings, each identical or nearly identical component shown in the various figures may be denoted by the same reference numeral. For clarity, not every component is labeled in each figure. Embodiments of various aspects of the invention will now be described by way of example and with reference to the accompanying drawings, wherein:

[0031] Figure 1 This is a schematic diagram of the apparatus for grinding metallographic samples to a fixed depth, as disclosed in an embodiment of the present invention.

[0032] Figure 2 This is a schematic diagram of the folding of the first conductive unit disclosed in an embodiment of the present invention;

[0033] Figure 3 This is a schematic diagram of the sample after inlaying, as disclosed in an embodiment of the present invention;

[0034] Figure 4 This is a schematic diagram of the fixture disclosed in an embodiment of the present invention.

[0035] The specific meanings of each mark in the diagram are as follows:

[0036] 1-Clamp; 2-Fixing part; 3-First conductive unit; 4-Second conductive unit; 4.1-Conductive post; 4.2-Wire; 5-Warning unit; 6-Metallic specimen after mounting; 7-Metallic specimen. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the scope of protection of the present invention. Unless otherwise defined, the technical or scientific terms used herein should have the ordinary meaning understood by those skilled in the art to which this invention pertains.

[0038] The terms "first," "second," and similar words used in the specification and claims of this patent application do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, unless the context clearly indicates otherwise, the singular forms of "an," "a," or "the," etc., do not indicate a quantity limitation, but rather indicate the presence of at least one. Terms such as "comprising" or "including" mean that the element or object preceding "comprising" encompasses the features, wholes, steps, operations, elements, and / or components listed following "comprising" or "including," and do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components, and / or collections thereof. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0039] Existing techniques for metallographic preparation of samples cannot achieve a fixed grinding depth. Conventional methods control the grinding depth by measuring while grinding, or by using automated grinding equipment to set the grinding depth of the metallographic sample with low precision and then manually controlling the grinding. Both of these methods have obvious drawbacks. Therefore, it is necessary to propose a solution that can achieve a fixed grinding depth, and that is low in cost and widely applicable.

[0040] Specific combination Figure 1 and Figure 3 The specific embodiment shown in the invention proposes an apparatus for grinding metallographic specimens at a fixed depth, including a clamp 1, a first conductive unit 3, a second conductive unit 4, and a warning unit 5. During installation, the first conductive unit 3 is embedded in the mounting material of the metallographic specimen 6 after mounting. The grinding surface of the metallographic specimen 6 after mounting is defined as the working surface, and the end of the first conductive unit 3 in the mounting material near the working surface is defined as the first end. The distance between the first end and the working surface along the grinding depth direction of the metallographic specimen 6 after mounting does not exceed the fixed depth to be ground of the metallographic specimen 6 after mounting. The clamp 2 is used to hold the metallographic specimen 6 after mounting. One end of the second conductive unit 4 is electrically connected to the first conductive unit 3, and the other end is connected to the warning unit 5. The first conductive unit 3, the second conductive unit 4, and the warning unit 5 in the metallographic specimen 6 after mounting to be ground form a conductive circuit.

[0041] Define the grinding depth direction of the mounted metallographic specimen 6 as the up-down direction, and the working surface as the bottom surface of the mounted metallographic specimen 6. Then, the bottom surface is horizontal, and the height of the highest point of the conductive circuit formed by the first end of the first conductive unit 3, the second conductive unit 4, and the warning unit 5 from the bottom surface is equal to the fixed depth to be ground of the mounted metallographic specimen 6. Then, when the working surface of the mounted metallographic specimen 6 is ground in the up-down direction until the conductive circuit is broken, the warning unit 5 broadcasts a warning signal, and the metallographic specimen 7 is ground to the fixed depth.

[0042] Combination Figure 2As shown, the first conductive unit 3 is configured as a metal filament, with two conductive sites formed at intervals on the upper bottom surface of the inlaid metallographic sample 6 at both ends along its length. As shown, any two points on the metal filament at different positions do not contact each other. Its first end is arranged within the inlay material around the metallographic sample 7 in a U-shaped arrangement, and the metal filament is spaced apart from the metallographic sample 7 to avoid short circuits caused by conductivity between the metal filament or the metallographic sample 7. The second conductive unit 4 consists of a conductive post 4.1 and a wire 4.2. The conductive post 4.1 includes a positive conductive post and a negative conductive post. The positive and negative conductive posts are respectively fixed on the clamp 1, with one end near the clamp 1 connected to the two conductive sites on the upper bottom surface of the inlaid metallographic sample 6 inside the clamp 1, and the other end away from the clamp 1 connected to the warning unit 5 via the wire 4.2. During specific installation, the bottom of the fixture 1 is provided with two through holes. The positions of the two through holes correspond to the positions of the two conductive positions on the bottom surface of the metallographic sample 6 after it is embedded inside the fixture 1. The positive conductive post and the negative conductive post are connected to the conductive positions through the two through holes to realize the electrical connection of the first conductive unit 3, the second conductive unit 4 and the warning unit 5.

[0043] Optionally, the warning unit 5 has its own power supply, which supplies power to the conductive circuit. When the conductive circuit is disconnected, the warning unit 5 directly broadcasts a warning signal. The warning unit 5 can be equipped with an alarm or an alarm light. Of course, the conductive circuit can also include a power supply, which supplies power to the first conductive unit 3, the second conductive unit 4, and the warning unit 5.

[0044] Combination Figure 3 In the specific embodiment shown, the first end of the metal wire wraps around the metallographic sample 7 at the same height within the insert. As shown, the metallographic sample 7 is designed as a cuboid structure. The metal wire extends to the bottom of the insert after wrapping around three sides of the cuboid structure at the same height, forming a conductive position to ensure that the grinding surface is horizontal when ground to a fixed depth. Furthermore, in a specific implementation, the first end of the first conductive unit 3 is modified from a metal wire to a mesh structure. The mesh structure is more stable and less prone to tilting, ensuring the accuracy of the grinding depth and improving its bonding strength with the insert, reducing the likelihood of the metal wire coming off during grinding and preventing a break in the circuit before reaching the target depth.

[0045] Optionally, in some embodiments, a microprocessor is added to the warning unit 5 to measure the resistance change of the conductive circuit. The grinding depth is inferred by the real-time change in the resistance of the conductive circuit, helping the operator to adjust the grinding parameters for more precise grinding control. In other embodiments, the first end surrounding the metallographic sample 7 is divided into several regions, and a voltage sensor is electrically connected to each region. The grinding depth change of the conductive units in each region is determined by the voltage change detected by the voltage sensor. Therefore, it can be determined whether the conductive units in a region are ground flush based on the changes in the sensor values. Furthermore, each voltage sensor can be electrically connected to the warning unit, allowing the warning unit to issue different warnings based on the sensed signals.

[0046] like Figure 4 As shown, the clamp 1 has a horizontal upper and lower bottom surface along the vertical direction. The clamp 1 is configured as a cavity structure with its lower bottom surface open upwards. The metallographic sample 6 is fixed in the cavity structure, and its lower bottom surface is parallel to and protrudes from the lower bottom surface of the clamp. For easy fixing, the shape and size of the metallographic sample 6 are adapted to be installed in the cavity structure of the clamp 1. In the illustrated embodiment, the metallographic sample 6 is configured as a first cylinder, and the cavity structure of the clamp 1 is configured as a second cylinder with dimensions adapted to the first cylinder, so that the metallographic sample 6 is placed exactly in the cavity structure.

[0047] To prevent the metallographic sample 6 from rotating during the grinding process after mounting, the outer wall of the cavity structure of the fixture 1 is uniformly and symmetrically provided with several fixing parts 2. The fixing parts 2 penetrate the outer wall of the cavity structure and abut against the outer wall of the mounted metallographic sample 6. In the embodiment, the fixing part 2 includes a fixing hole penetrating the outer wall of the cavity structure and a bolt adapted to fix it to the fixing hole. The fixing parts 2 are symmetrically arranged radially along the cylindrical fixture 1.

[0048] The device for grinding metallographic specimens at a fixed depth proposed in this invention grinds the fixture 1 and the embedded metallographic specimen 6 inside it simultaneously on the working surface. At the same time, in order to ensure that the conductive circuit is realized only by the set structure, the fixture 1 is made of insulating material, such as plastic.

[0049] The method for grinding metallographic specimens at a fixed depth proposed in this invention comprises the following principles: a sensing element is simultaneously embedded during the mounting of a metallographic specimen of the target size. The sensing height of the sensing element is set at a fixed depth to be ground on the metallographic specimen. The sensing element is electrically or signal-connected to an alarm unit, which issues an alarm when the sensing element is open-circuited or its signal is interrupted. The grinding process of the metallographic specimen is monitored, with the specimen and the sensing element grinding synchronously. When the metallographic specimen is ground to the sensing height of the sensing element, the alarm unit, electrically or signal-connected to the sensing element, broadcasts an alarm signal. The above-described apparatus for grinding metallographic specimens at a fixed depth is merely one specific embodiment of the method described in this invention.

[0050] The method for grinding metallographic specimens at a fixed depth, based on the aforementioned apparatus, specifically includes the following steps:

[0051] 1) Obtain a sample to be ground of a preset size, typically by cutting to obtain the metallographic specimen 7; 2) After arranging the sample to be ground and the first conductive unit 3 in the mounting machine according to the preset position requirements, add mounting material to mount the sample to be ground, obtaining the mounted metallographic specimen 6, such as... Figure 3 The structure shown; 3) Place the inlaid metallographic sample 6 into the fixture 1 and fix it, so that the first conductive unit 3, the second conductive unit 4 and the warning unit 5 are electrically connected, and the connection effect is as follows. Figure 1 As shown; 4) Grind the inlaid metallographic sample 6 held by the fixture 1 in the up-down direction. During grinding, the fixture 1 and the inlaid metallographic sample 6 are ground synchronously until the warning unit 5 issues a warning, indicating that the highest point of the conductive circuit formed by the first end of the first conductive unit 3 in the inlaid metallographic sample 6 with the second conductive unit 4 and the warning unit 5 has been ground away. Grinding is stopped, and a metallographic sample 7 with a fixed grinding depth is obtained. In the embodiment, because the first end of the metal wire extends to the bottom of the inlay material after circling around the three sides of the rectangular structure of the metallographic sample 7 at the same height to form a conductive position, the conductive circuit is broken when all the metal wires at the first end are ground.

[0052] The technical problem to be solved by the present invention is that the existing metallographic sample preparation grinding and polishing methods are difficult to accurately control the grinding depth, and the time and economic costs are relatively high. In order to solve this problem, the present invention proposes an apparatus and method for grinding metallographic samples at a fixed depth. When the metallographic sample 7 is mounted, a metal wire of the required grinding and polishing depth is placed. During grinding, the metal wire and the fixture 1 form a conductive circuit. When the grinding reaches the required depth, the part of the metal wire that forms the conductive circuit is ground away, the conductive circuit is broken, the alarm is triggered, and the grinding stops, thereby achieving precise control of the fixed depth of the metallographic sample 7.

[0053] The apparatus and method for grinding metallographic samples at a fixed depth, as disclosed in this invention, will be further described in detail below with reference to specific embodiments.

[0054] Example 1

[0055] (1) Sample pretreatment

[0056] ① Select the X65MS pipeline steel to be ground and cut it into metallographic specimen 7 to be inlaid, with a size of 10mm*10mm*6mm.

[0057] (2) Sample mounting

[0058] ① Place metallographic sample 7 in the mounting machine;

[0059] ② Place a 30μm metal wire next to metallographic sample 7 and fold it upwards. The folding pattern can be as follows: Figure 2 As shown;

[0060] ③Inlay material is added to mount the metallographic sample 7.

[0061] (3) Sample clamping

[0062] ①The thickness of the metallographic sample 6 after mounting is 16.502μm. It is placed in the fixture 1 so that the metal wire is connected to the positive and negative conductive posts set on the fixture 1.

[0063] (4) Grinding of the sample

[0064] ① Grind the fixture 1 together with the inlaid metallographic sample 6. During the grinding process, the alarm detects the change in current in the conductive circuit through the ammeter. The voltage in the conductive circuit is set to 3V and the current threshold is set to 10mA. When the current in the conductive circuit is less than this threshold, the alarm will sound to indicate that the fixed grinding depth is about to be reached. As shown in Table 1 below, the initial ammeter reading is 254mA. As the grinding progresses, the ammeter reading gradually decreases. When the grinding reaches 30μm, the ammeter reading is 0, and the alarm will sound to indicate that the grinding is complete.

[0065] ② The alarm will sound when the metal filaments disappear during grinding;

[0066] ③ Stop grinding. The thickness of the inlaid metallographic sample 6 after grinding is 16.472μm, and the metallographic sample 7 with a precisely controlled grinding depth of 30μm is obtained.

[0067] Table 1. Data on the change in conductive circuit current detected by the warning unit.

[0068] Grinding depth (μm) 0 10 20 30 Ammeter reading (mA) 254 179 58 0

[0069] The apparatus and method for grinding metallographic samples to a fixed depth proposed in this invention achieves grinding to a fixed depth by placing a conductive unit with the required grinding depth near the metallographic sample and extending into the interior of the mounting material during mounting, and judging the grinding progress by the on / off state of the conductive circuit. This invention can be widely applied to the fixed-depth grinding of different samples at a low cost.

[0070] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Those skilled in the art can make various modifications and refinements without departing from the spirit and scope of the invention. Therefore, the scope of protection of the present invention shall be determined by the claims.

Claims

1. An apparatus for grinding a fixed depth metallographic specimen, comprising: It includes a clamp, a first conductive unit, a second conductive unit, and a warning unit; The first conductive unit is embedded in the mounting material of the embedded metallographic sample; the grinding surface of the embedded metallographic sample is defined as the working surface, and the end of the first conductive unit in the mounting material near the working surface is defined as the first end. Then, the distance between the first end and the working surface along the grinding depth direction of the embedded metallographic sample does not exceed the fixed depth to be ground of the embedded metallographic sample. The fixture is used to hold the inlaid metallographic sample. One end of the second conductive unit is electrically connected to the first conductive unit and the other end is connected to the warning unit. The first conductive unit, the second conductive unit, and the warning unit in the inlaid metallographic sample to be ground form a conductive circuit. The grinding depth direction of the mounted metallographic specimen is defined as the up-down direction, and the working surface is the bottom surface of the mounted metallographic specimen. The bottom surface is horizontal, and the height of the highest point of the conductive circuit formed by the first end of the first conductive unit, the second conductive unit, and the warning unit from the bottom surface is equal to the fixed grinding depth of the mounted metallographic specimen. Then, when the working surface of the mounted metallographic specimen is ground along the up-down direction until the conductive circuit is broken, the warning unit broadcasts a warning signal, and the metallographic specimen is ground to the fixed depth.

2. The apparatus of claim 1, wherein, The first conductive unit is configured as a metal wire, and the two ends of the metal wire in the length direction form two conductive sites at intervals on the upper bottom surface of the inlaid metallographic sample. Any two points on the metal filament at different positions do not contact each other, and its first end is arranged around the metallographic sample within the inlay material, with the metal filament and the metallographic sample being spaced apart.

3. The apparatus of claim 2, wherein, The second conductive unit includes a positive conductive post, a negative conductive post, and a wire; the positive and negative conductive posts are respectively fixed on the fixture, with the end of the post near the fixture connected to two conductive positions on the bottom surface of the metallographic sample after it is embedded inside the fixture, and the end of the post away from the fixture connected to the warning unit by the wire.

4. The apparatus of claim 2, wherein, The clamp has a horizontal upper and lower bottom surface along the vertical direction, and the clamp is configured as a cavity structure with the lower bottom surface open from the lower bottom surface upward; the metallographic sample after mounting is fixed in the cavity structure, and the lower bottom surface of the metallographic sample after mounting is parallel to and protrudes downward from the lower bottom surface of the clamp in the cavity structure.

5. The apparatus of claim 4, wherein, The inlaid metallographic sample is fitted with a shape and size that are adapted to the cavity structure of the fixture.

6. The apparatus of claim 4, wherein, The outer wall of the cavity structure of the fixture is uniformly and symmetrically provided with several fixing parts, which penetrate the outer wall of the cavity structure and abut against the outer wall of the inlaid metallographic sample.

7. The apparatus of claim 1, wherein, The first end of the first conductive unit surrounds the metallographic sample at the same height within the insert.

8. The apparatus of claim 3, wherein, The fixture has two through holes at its bottom. The positions of the two through holes correspond to the positions of two conductive sites on the bottom surface of the metallographic sample after it is embedded inside the fixture. The positive and negative conductive posts are connected to the conductive sites through the two through holes.

9. A method for grinding a metallographic sample at a fixed depth, characterized in that, include: A sensing element is simultaneously embedded when a metallographic sample of the target size is mounted. The sensing height of the sensing element is set at a fixed depth position of the metallographic sample to be ground. The sensing element is electrically or signalally connected to an alarm unit, which is used to issue an alarm when the sensing element is open-circuited or the signal is interrupted. The grinding process of the metallographic sample is monitored. The metallographic sample and the sensing element are ground synchronously. When the metallographic sample is ground to the sensing height of the sensing element, the warning unit electrically or signalally connected to the sensing element broadcasts a warning signal.

10. A method of grinding a fixed depth metallographic specimen, characterized by, The apparatus for grinding metallographic specimens at a fixed depth according to any one of claims 1-8 comprises the following steps: 1) Obtain a sample to be ground of a preset size; 2) After the sample to be ground and the first conductive unit are arranged in the mounting machine according to the preset position requirements, the mounting material is added to mount the sample to be ground to obtain the mounted metallographic sample. 3) Place the inlaid metallographic sample in the fixture and fix it so that the first conductive unit, the second conductive unit and the warning unit are electrically connected; 4) Grind the inlaid metallographic sample held by the fixture along the up and down direction until the warning unit issues a warning, indicating that the highest point of the conductive circuit formed by the first end of the first conductive unit, the second conductive unit, and the warning unit in the inlaid metallographic sample has been ground away. Stop grinding and obtain a metallographic sample with a fixed grinding depth.

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