Drilling device for detecting residual stress of machine tool body and using method

Abstract

The invention discloses a drilling device for detecting residual stress of a machine tool body and a using method, belongs to the field of stress testing equipment, and aims to solve the problems in the prior art that residual stress measuring holes are drilled by adopting a blind hole method. The device comprises a magnetic base, an XY-axis fine tuning platform, a T-shaped plate, a vertical connecting plate and a drill bushing, the plane connecting plate is arranged on the magnetic base, the XY-axis fine adjustment platform is arranged on the plane connecting plate, the T-shaped plate is connected with the output end of the XY-axis fine adjustment platform, the vertical displacement mechanism is arranged on the T-shaped plate, the vertical connecting plate is connected with the output end of the vertical displacement mechanism, the drill bushing is connected with the vertical connecting plate, and a vertically-through positioning hole is formed in the drill bushing. And a hard alloy wear-resistant sleeve is embedded in the positioning hole. The drilling position adjusting precision is high, stable drilling driving force is provided by means of the self weight of the drilling motor, manual operation errors are reduced, the layer-by-layer drilling requirement is met, and compared with a traditional magnetic drilling frame, the efficiency is higher.

Description

Technical Field

[0001] The invention belongs to the technical field of metal cutting machine tool manufacturing, and in particular relates to a drilling device for detecting residual stress of a machine tool bed and a use method thereof. Background Art

[0002] Residual stress is the stress that remains inside the workpiece after the external load is removed. During the manufacturing process of the machine tool bed, residual stresses of varying degrees will be generated inside the bed due to uneven heat or force. These residual stresses are the result of the process, mainly including casting stress, welding stress, processing stress and thermal stress. When these factors disappear, some of the effects still remain inside the machine tool bed, forming residual stress. This residual stress is unstable and tends to return to a stress-free state, so it will cause the machine tool bed to gradually deform and lose its original precision, which will greatly affect the dimensional stability, rigidity, strength, etc. of the machine tool bed, thereby affecting the assembly and normal use of the machine tool. Especially for metal cutting machine tools, the residual stress of the bed will even affect the machining performance of the machine tool.

[0003] There are many methods for testing residual stress. The method that is widely used now is the blind hole method. The basic principle of this test method is to use mechanical processing methods to drill a blind hole with a diameter of 1.5mm and a depth of 2mm on the component to be tested, so that the edge of the hole will produce corresponding displacement and strain due to the release of part of the stress. These displacements or strains are measured using resistance strain gauges, and the original stress at the component processing point is obtained after conversion.

[0004] From the experimental steps of the blind hole method for detecting residual stress, it can be seen that drilling qualified holes according to the requirements, that is, ensuring the concentricity of the drilled hole and the center of the circle on the strain gauge, reducing or eliminating manual operation errors is the key factor in improving detection accuracy, stability and efficiency.

[0005] Therefore, when using the blind hole method to detect residual stress drilling, it is necessary to use a drilling device to ensure the drilling accuracy. A commonly used drilling device is a magnetic base drill stand.

[0006] The magnetic drill stand is suitable for plane measurement of ferromagnetic materials such as machine tool beds. The magnetic drill stand uses a gear rack mechanism to adjust the horizontal position for drilling center positioning, and the positioning is not accurate. At the same time, during the drilling process, manual drilling is required. The driving force introduced by manual operation cannot be determined, and the driving force error is large; and the magnetic drill stand can only meet the specified 2mm depth of drilling, and cannot achieve layer-by-layer drilling.

[0007] Layer-by-layer drilling means that a certain depth can be specified, such as 0.25mm per layer, and holes are drilled layer by layer. The displacement and strain generated by the release of stress in each layer are measured once. Generally, 8 layers are drilled, with a total depth of 2mm. After obtaining the displacement and strain generated in each layer, a series of formulas can be used to calculate the uniform residual stress including the strain of each layer. The uniform residual stress has a smaller error than the residual stress obtained by drilling a 2mm deep hole at one time, and the calculation result is closer to the true value.

[0008] Therefore, it is necessary to improve the existing drilling rack structure to solve problems such as poor centering accuracy, large manual operation errors and inability to drill layer by layer. Summary of the invention

[0009] The purpose of the present invention is to provide a drilling device for residual stress detection of a machine tool bed, so as to solve the problems existing in the prior art of drilling residual stress measurement holes by blind hole method. The technical solution adopted by the present invention is as follows:

[0010] A drilling device for residual stress detection of a machine tool bed comprises a magnetic base, a plane connecting plate, an XY-axis fine-tuning platform, a T-plate, a vertical displacement mechanism, a vertical connecting plate and a drill sleeve; the plane connecting plate is arranged on the magnetic base, the XY-axis fine-tuning platform is arranged on the plane connecting plate, the T-plate is connected to the output end of the XY-axis fine-tuning platform, the vertical displacement mechanism is arranged on the T-plate, the vertical connecting plate is connected to the output end of the vertical displacement mechanism, the drill sleeve is connected to the vertical connecting plate, and a positioning hole which passes through from top to bottom is provided on the drill sleeve, and a hard alloy wear-resistant sleeve is embedded in the positioning hole.

[0011] Furthermore, the model of the vertical displacement mechanism is ELCSS16L-B2.5-30-S.

[0012] Furthermore, the model of the XY-axis fine-tuning platform is LBY60-LH.

[0013] Furthermore, the outer dimensions of the magnetic base are 120mm*55mm*50mm.

[0014] The present invention also provides a method for using a drilling device for detecting residual stress of a machine tool bed, which is implemented based on the above-mentioned drilling device for detecting residual stress of a machine tool bed, and includes the following steps:

[0015] Step 1: Surface treatment of the machine tool bed under test: First, observe the surface condition of the machine tool bed under test, paste the strain gauge on the drilling point on the machine tool bed under test, and electrically connect the strain gauge to the strain gauge to ensure that the strain gauge is firmly pasted without bubbles; ensure that the plane on the machine tool bed under test where the drilling device is placed is flat, smooth and free of impurities, so as to provide favorable conditions for ensuring a strong magnetic connection between the magnetic base and the machine tool bed under test, and at the same time ensure that the drill sleeve is perpendicular to the surface of the machine tool bed under test;

[0016] Step 2: Fix the automatic drilling device: Place the drilling device on the surface of the machine tool bed material, observe the center of the strain gauge through the drill sleeve, preliminarily align the center of the drill sleeve with the center of the strain gauge, rotate the switch knob on the magnetic base counterclockwise, point the switch knob to the + position, and ensure that the magnetic base is firmly connected to the machine tool bed under test;

[0017] Step 3, adjusting the vertical displacement: placing a high-power magnifying glass in the drill sleeve, and adjusting the distance between the high-power magnifying glass and the strain gauge up and down by controlling the stepping motor of the vertical displacement mechanism until the strain gauge can be clearly observed in the high-power magnifying glass;

[0018] Step 4, adjust the horizontal displacement: adjust the two micrometer heads of the XY axis fine-tuning platform in sequence, so that the center of the crosshairs of the high-power magnifying glass completely coincides with the center of the strain gauge, and then use the opposing clamping mechanism and friction locking mechanism of the XY axis fine-tuning platform to double lock the XY axis fine-tuning platform to ensure that the drill sleeve and the strain gauge have accurate and stable concentricity when drilling;

[0019] Step 5, drilling: take out the high-power magnifying glass from the drill sleeve, insert the drilling motor with the drill bit into the drill sleeve, adjust the speed of the drilling motor to 60000r / min, control the output end of the vertical displacement mechanism to move downward, so that the drilling end of the drill bit fits the strain gauge, and then set the stepper motor operating parameters of the vertical displacement mechanism, set the drilling depth to 2mm, divide the hole depth into 8 layers, each layer has a depth of 0.25mm, and make the output end of the vertical displacement mechanism descend at a speed of one layer per minute. Pause for 1 minute between two layers of drilling to allow the strain gauge to collect the displacement or strain of the strain gauge. The total time is 15 minutes;

[0020] Step 6. Remove the automatic drilling device: After obtaining the data collected by the strain gauge, control the output end of the vertical displacement mechanism to move upward to ensure that the drill bit of the drilling motor leaves the machine tool bed under test, adjust the speed of the drilling motor to 0r / min, remove the drilling motor from the drill sleeve, rotate the switch knob on the magnetic base clockwise, point the switch knob to the - gear, separate the magnetic base from the machine tool bed under test, and prepare to drill the next point to be tested.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. A large-sized magnetic base with a larger internal permanent magnet is selected so that the suction force generated by the magnetic base can reach 1500N for the automatic drilling device of the present invention. Therefore, the drilling device of the present invention is more firmly combined with the bed of the machine tool to be tested.

[0023] 2. The transmission components used in the XY gear rack horizontal displacement platform in the traditional magnetic base are gears and racks, which are suitable for rapid adjustment but not for precise positioning, with an accuracy of 0.1mm. The transmission components used in the XY axis fine-tuning platform of the present invention are differential heads, which are suitable for precise adjustment in units of 0.01mm. Therefore, the horizontal displacement adjustment accuracy of the drilling device of the present invention is improved by 10 times, and the adjustment accuracy is higher.

[0024] 3. The traditional magnetic base drill rig is equipped with a drill rod and a low-speed hand drill. The manual operation error is large when drilling a 2mm deep hole. The drilling device of the present invention uses a vertical displacement mechanism and a high-speed drilling motor for drilling. The drilling motor can provide a stable drilling driving force by its own weight, reducing the manual operation error. At the same time, the traditional magnetic base drill rig cannot achieve layer-by-layer drilling, and can only drill a 2mm deep hole at a time for stress measurement. The minimum feed amount of the vertical displacement mechanism in the drilling device of the present invention is 0.002mm, which meets the 0.25mm feed depth per layer required for conventional layer-by-layer drilling, so that the comprehensive stress error obtained by subsequent calculation is smaller. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the structure of the device of the present invention;

[0026] Figure 2 It is a schematic diagram of the structure of the magnetic base;

[0027] Figure 3 It is a structural schematic diagram of a plane connecting plate;

[0028] Figure 4 It is a structural diagram of the XY axis fine adjustment platform;

[0029] Figure 5 It is a schematic diagram of the structure of the T-type plate;

[0030] Figure 6 It is a structural schematic diagram of the vertical displacement mechanism;

[0031] Figure 7 is a structural schematic diagram of a vertical connecting plate;

[0032] Figure 8 It is a structural diagram of a drill sleeve.

[0033] In the figure, 1. magnetic base, 2. plane connecting plate, 3. XY axis fine-tuning platform, 4. T-plate, 5. vertical displacement mechanism, 6. vertical connecting plate, 7. drill sleeve, 8. hard alloy wear-resistant sleeve. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is described below by the specific embodiments shown in the accompanying drawings. However, it should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present invention.

[0035] The connection mentioned in the present invention is divided into fixed connection and detachable connection. The fixed connection is a non-detachable connection including but not limited to conventional fixed connection methods such as folding connection, rivet connection, bonding connection and welding connection. The detachable connection includes but not limited to conventional detachable methods such as bolt connection, snap connection, pin connection and hinge connection. When the specific connection method is not clearly defined, it is assumed that at least one connection method can be found in the existing connection methods to achieve the function, and those skilled in the art can choose according to their needs. For example: welding connection is selected for fixed connection, and bolt connection is selected for detachable connection.

[0036] The present invention will be further described in detail below in conjunction with the accompanying drawings. The following embodiments are provided to explain the present invention, but the present invention is not limited to the following embodiments.

[0037] Embodiment 1: Figures 1 to 8 As shown, a drilling device for residual stress detection of a machine tool bed comprises a magnetic base 1, a plane connecting plate 2, an XY-axis fine-tuning platform 3, a T-plate 4, a vertical displacement mechanism 5, a vertical connecting plate 6 and a drill sleeve 7; the plane connecting plate 2 is arranged on the magnetic base 1, the XY-axis fine-tuning platform 3 is arranged on the plane connecting plate 2, the T-plate 4 is connected to the output end of the XY-axis fine-tuning platform 3, the vertical displacement mechanism 5 is arranged on the T-plate 4, the vertical connecting plate 6 is connected to the output end of the vertical displacement mechanism 5, the drill sleeve 7 is connected to the vertical connecting plate 6, and the drill sleeve 7 is provided with a positioning hole which passes through from top to bottom, and a hard alloy wear-resistant sleeve 8 is embedded in the positioning hole.

[0038] The switch knob on the magnetic base 1 can be turned to the + position or the - position to control the permanent magnet inside it to form a magnetic field or cut off the magnetic field. When the permanent magnet inside the magnetic base 1 forms a magnetic field, the suction force generated by the magnetic base 1 can reach 1500N. It has a compact structure and strong magnetic force, and can be reliably fixed on the bed of a machine tool to be tested, such as a machine tool bed.

[0039] The four holes distributed in the middle of the planar connecting plate 2 are used to connect with the magnetic base 1 through bolts, and the holes distributed at the four corners of the planar connecting plate 2 are used to connect with the XY axis fine-tuning platform 3 through bolts.

[0040] The XY axis fine-tuning platform 3 is composed of two uniaxial fine-tuning platforms with the same structure connected by bolts, so as to realize the horizontal displacement adjustment of the X axis and the Y axis. The uniaxial displacement platform includes a table, a base, a ball, a differential head, an opposing clamping mechanism and a friction locking mechanism. The table and the base are connected together by adding a ball at the junction of the groove at the bottom of the table and the groove at the top of the base. The ball and the track are in four-point contact at 45 degrees. This structure can achieve high-precision and smooth movement. The moving stroke of the table is ±6.5mm. The friction locking mechanism is composed of a locking plate and a locking screw fixed on the side of the base. The locking screw is used to press the locking plate to generate friction to fix the table. The opposing clamping mechanism is composed of an opposing stop screw and a locking nut. The L-shaped plate fixed on the side of the table by the top of the opposing stop screw and the top of the differential head is clamped against each other, so that a vibration-resistant and highly reliable fixing force can be obtained. The differential head uses the principle of gears to convert the rotation of rotary motion into linear insertion and withdrawal actions. It uses a third-order differential action between two gears of different diameters to convert subtle changes in rotation into linear insertion and withdrawal actions, thereby achieving precise control of tiny distances with an accuracy of 0.01mm.

[0041] The T-shaped plate 4 includes a flat plate and a vertical plate. The lower end of the vertical plate is connected to the middle of the flat plate to form an inverted T-shaped structure. The holes distributed on the four corners of the flat plate are used to connect to the output end table of the XY-axis fine-tuning platform 3 through bolts, and the 6 holes distributed on the vertical plate are used to connect to the vertical displacement mechanism 5 through bolts.

[0042] The vertical displacement mechanism 5 is connected to the six holes distributed on the upper part of the vertical connection plate 6 through bolts, and the four holes distributed on the lower part of the vertical connection plate 6 are connected to the drill sleeve 7 through bolts.

[0043] The drill sleeve 7 serves to fix the magnifying glass or the drilling motor. The magnifying glass or the drilling motor requires frequent replacement of the drill bit. Long-term plugging and unplugging of the magnifying glass or the drilling motor will cause wear to the drill sleeve 7, resulting in the magnifying glass or the drilling motor being too loose when being fixed. Therefore, a carbide wear-resistant sleeve 8 is embedded in the inner hole of the drill sleeve 7 to improve the wear resistance of the drill sleeve 7.

[0044] The vertical displacement mechanism 5 is composed of a stepper motor and a vertical electric cylinder. The stepper motor controls the vertical movement of the piston rod through the internal toothed belt and pulley, and controls the vertical electric cylinder to move to a certain position and keep the position unchanged by controlling the brake mechanism inside the motor. The vertical electric cylinder is composed of a cylinder body and a piston rod. A passive slider is fixed on the cylinder body, and the piston rod includes an active guide rail vertical plane. The stepper motor is controlled to realize the vertical movement of the active guide rail vertical plane along the passive slider. The movement stroke of the piston rod in the cylinder body is 30mm, and the accuracy is 0.002mm.

[0045] The model of the vertical displacement mechanism 5 is ELCSS16L-B2.5-30-S.

[0046] The model of the XY-axis fine-tuning platform 3 is LBY60-LH.

[0047] The outer dimensions of the magnetic base 1 are 120 mm*55 mm*50 mm.

[0048] Embodiment 2: Figures 1 to 8 As shown, a method for using a drilling device for detecting residual stress of a machine tool bed is implemented based on the drilling device for detecting residual stress of a machine tool bed described in Example 1, and includes the following steps:

[0049] Step 1: Surface treatment of the machine tool bed under test: First, observe the surface condition of the machine tool bed under test, paste strain gauges on the points to be drilled on the machine tool bed under test, and electrically connect the strain gauges to the strain gauges to ensure that the strain gauges are firmly pasted without bubbles; ensure that the plane on the machine tool bed under test where the drilling device is placed is flat, smooth and free of impurities, thereby providing favorable conditions for ensuring a strong magnetic connection between the magnetic base 1 and the machine tool bed under test, and at the same time ensure that the drill sleeve 7 is perpendicular to the surface of the machine tool bed under test;

[0050] Step 2, fix the automatic drilling device: place the drilling device on the surface of the machine tool bed material, observe the center of the strain gauge through the drill sleeve 7, preliminarily align the center of the drill sleeve 7 with the center of the strain gauge, rotate the switch knob on the magnetic base 1 counterclockwise, point the switch knob to the + position, and ensure that the magnetic base 1 is firmly connected to the machine tool bed under test;

[0051] Step 3, adjusting the vertical displacement: a high-power magnifying glass is placed in the drill sleeve 7, and the distance between the high-power magnifying glass and the strain gauge is adjusted up and down by controlling the stepping motor of the vertical displacement mechanism 5 until the strain gauge can be clearly observed in the high-power magnifying glass;

[0052] Step 4, adjusting the horizontal displacement: sequentially adjust the two micrometer heads of the XY-axis fine-tuning platform 3 so that the crosshair center of the high-power magnifying glass completely coincides with the center of the strain gauge, and then use the opposing clamping mechanism and friction locking mechanism of the XY-axis fine-tuning platform 3 to double-lock the XY-axis fine-tuning platform 3 to ensure that the drill sleeve 7 and the strain gauge have accurate and stable concentricity when drilling;

[0053] Step 5, drilling: take out the high-power magnifying glass from the drill sleeve 7, insert the drilling motor with the drill bit into the drill sleeve 7, adjust the speed of the drilling motor to 60000r / min, control the output end of the vertical displacement mechanism 5 to move downward, so that the drilling end of the drill bit fits the strain gauge, and then set the stepper motor operating parameters of the vertical displacement mechanism 5, set the drilling depth to 2mm, divide the hole depth into 8 layers, each layer has a depth of 0.25mm, and make the output end of the vertical displacement mechanism 5 descend at a speed of one layer per minute, pause for 1 minute between two layers of drilling, so that the strain gauge collects the displacement or strain of the strain gauge, and the total time is 15 minutes;

[0054] Step 6. Remove the automatic drilling device: After obtaining the data collected by the strain gauge, control the output end of the vertical displacement mechanism 5 to move upward to ensure that the drill bit of the drilling motor leaves the machine tool bed under test, adjust the speed of the drilling motor to 0r / min, remove the drilling motor from the drill sleeve 7, rotate the switch knob on the magnetic base 1 clockwise, point the switch knob to the - gear, separate the magnetic base 1 from the machine tool bed under test, and prepare to drill the next point to be tested.

[0055] The advantages of the present invention are as follows:

[0056] 1. A large-sized magnetic base 1 with a larger internal permanent magnet is selected so that the suction force generated by the magnetic base 1 can reach 1500N for the automatic drilling device of the present invention. Therefore, the drilling device of the present invention is more firmly combined with the bed of the machine tool to be tested.

[0057] 2. The transmission components used in the XY gear rack horizontal displacement platform in the traditional magnetic base are gears and racks, which are suitable for rapid adjustment but not for precise positioning, with an accuracy of 0.1mm. The transmission components used in the XY axis fine-tuning platform 3 of the present invention are differential heads, which are suitable for precise adjustment in units of 0.01mm. Therefore, the horizontal displacement adjustment accuracy of the drilling device of the present invention is improved by 10 times, and the adjustment accuracy is higher.

[0058] 3. The traditional magnetic base drill rig is equipped with a drill rod and a low-speed hand drill. The manual operation error is large when drilling a 2mm deep hole. The drilling device of the present invention uses a vertical displacement mechanism 5 with a high-speed drilling motor for drilling. The drilling motor can provide a stable drilling driving force by its own weight, reducing the manual operation error. At the same time, the traditional magnetic base drill rig cannot achieve layer-by-layer drilling, and can only drill a 2mm deep hole at a time for stress measurement. The minimum feed amount of the vertical displacement mechanism 5 in the drilling device of the present invention is 0.002mm, which meets the 0.25mm feed depth per layer required for conventional layer-by-layer drilling, so that the comprehensive stress error obtained by subsequent calculation is smaller.

[0059] The above embodiments are merely exemplary descriptions of the present invention and do not limit its protection scope. Those skilled in the art may also make partial changes thereto, which are within the protection scope of the present invention as long as they do not exceed the spirit of the present invention.

Claims

1. A drilling device for residual stress detection of a machine tool bed, characterized in that: The invention comprises a magnetic base (1), a plane connecting plate (2), an XY-axis fine-tuning platform (3), a T-shaped plate (4), a vertical displacement mechanism (5), a vertical connecting plate (6) and a drill sleeve (7); the plane connecting plate (2) is arranged on the magnetic base (1), the XY-axis fine-tuning platform (3) is arranged on the plane connecting plate (2), the T-shaped plate (4) is connected to the output end of the XY-axis fine-tuning platform (3), the vertical displacement mechanism (5) is arranged on the T-shaped plate (4), the vertical connecting plate (6) is connected to the output end of the vertical displacement mechanism (5), the drill sleeve (7) is connected to the vertical connecting plate (6), and a positioning hole which passes through from top to bottom is provided on the drill sleeve (7), and a hard alloy wear-resistant sleeve (8) is embedded in the positioning hole.

2. A drilling device for residual stress detection of a machine tool bed according to claim 1, characterized in that: The vertical displacement mechanism (5) is composed of a stepping motor and a vertical electric cylinder.

3. A drilling device for residual stress detection of a machine tool bed according to claim 2, characterized in that: The model of the vertical displacement mechanism (5) is ELCSS16L-B2.5-30-S.

4. A drilling device for residual stress detection of a machine tool bed according to claim 3, characterized in that: The model of the XY-axis fine-tuning platform (3) is LBY60-LH.

5. The drilling device for residual stress detection of a machine tool bed according to claim 3, characterized in that: The outer dimensions of the magnetic base (1) are 120 mm*55 mm*50 mm.

6. A method for using a drilling device for detecting residual stress of a machine tool bed, which is realized by relying on a drilling device for detecting residual stress of a machine tool bed according to any one of claims 2 to 5, characterized in that: The following steps are involved: Step 1: Surface treatment of the machine tool bed under test: First, observe the surface condition of the machine tool bed under test, paste strain gauges on the points to be drilled on the machine tool bed under test, and electrically connect the strain gauges to the strain gauges to ensure that the strain gauges are firmly pasted and free of bubbles; ensure that the surface of the machine tool bed under test on which the drilling device is placed is flat, smooth, and free of impurities, thereby providing favorable conditions for ensuring a strong magnetic connection between the magnetic base (1) and the machine tool bed under test, and at the same time ensure that the drill sleeve (7) is perpendicular to the surface of the machine tool bed under test; Step 2, fix the automatic drilling device: place the drilling device on the surface of the machine tool bed material, observe the center of the strain gauge through the drill sleeve (7), preliminarily align the center of the drill sleeve (7) with the center of the strain gauge, rotate the switch knob on the magnetic base (1) counterclockwise, point the switch knob to the + position, and ensure that the magnetic base (1) is firmly connected to the machine tool bed under test; Step 3, adjusting the vertical displacement: placing a high-power magnifying glass in the drill sleeve (7), and adjusting the distance between the high-power magnifying glass and the strain gauge up and down by controlling the stepping motor of the vertical displacement mechanism (5), until the strain gauge can be clearly observed in the high-power magnifying glass; Step 4, adjusting the horizontal displacement: sequentially adjusting the two micrometer heads of the XY-axis fine-tuning platform (3) so that the center of the crosshairs of the high-power magnifying glass completely coincides with the center of the strain gauge, and then using the opposing clamping mechanism and the friction locking mechanism of the XY-axis fine-tuning platform (3) to double-lock the XY-axis fine-tuning platform (3) to ensure that the drill sleeve (7) and the strain gauge have accurate and stable concentricity when drilling; Step 5, drilling: remove the high-power magnifying glass from the drill sleeve (7), insert the drilling motor with the drill bit into the drill sleeve (7), adjust the speed of the drilling motor to 60000 r / min, control the output end of the vertical displacement mechanism (5) to move downward, so that the drilling end of the drill bit fits the strain gauge, and then set the stepper motor operating parameters of the vertical displacement mechanism (5), set the drilling depth to 2 mm, divide the hole depth into 8 layers, each layer has a depth of 0.25 mm, and make the output end of the vertical displacement mechanism (5) descend at a speed of one layer per minute. Pause for 1 minute between two layers of drilling to allow the strain gauge to collect the displacement or strain of the strain gauge. The total time is 15 minutes; Step 6. Remove the automatic drilling device: After obtaining the data collected by the strain gauge, control the output end of the vertical displacement mechanism (5) to move upward to ensure that the drill bit of the drilling motor leaves the bed of the machine tool under test, adjust the speed of the drilling motor to 0 r / min, remove the drilling motor from the drill sleeve (7), rotate the switch knob on the magnetic base (1) clockwise to point the switch knob to the negative position, separate the magnetic base (1) from the bed of the machine tool under test, and prepare to drill the next point to be tested.

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