Device, machine tool and method for restraining composite material drilling damage through negative pressure

Abstract

The invention discloses a device, a machine tool and a method for restraining composite material drilling damage through negative pressure, solves the problem that in the prior art, damage is prone to occurring in the composite material machining process, and has the beneficial effect of avoiding composite material damage, and according to the specific scheme, the device for restraining composite material drilling damage through negative pressure comprises a shell; the shell supports the cutter clamping piece, the cutter clamping piece is used for installing the hollow drill, the hollow drill is exposed out of the shell, the cutter clamping piece drives the hollow drill to rotate relative to the shell, the shell is independently connected with the vacuum generator and the air generator, the shell is hollow, and the cutter clamping piece is communicated with the interior of the shell and the interior of the hollow drill. When the vacuum generator works, air at the position of the hollow drill is exhausted through the shell and the cutter clamping piece so that upward pulling force can be provided for a composite material to avoid drill hole damage, and air generated when the air generator works is used for blowing away cut materials at the position of the hollow drill.

Description

Technical Field

[0001] The invention relates to the field of composite material processing, in particular to a device, a machine tool and a method for suppressing composite material drilling damage by using negative pressure. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] Composite materials are widely used in aerospace, automobile manufacturing and other fields due to their excellent strength, stiffness and lightweight characteristics. However, due to their lamination characteristics and anisotropy, various damage defects are prone to occur during the processing due to the interaction between the drill bit and the material. Delamination is one of the most common and serious defects, mainly including hole wall delamination and exit delamination, which occurs at various stages of drilling. The main reason is that the feed force gradually squeezes the composite material (composite material) downward during the drilling process, which easily causes delamination problems in the composite material. At present, in order to prevent delamination, the bonding strength is improved by laminating with metal materials, which will cause mechanical burns, etc., thereby generating cracks and burrs, which not only affects the processing quality of the composite workpiece, but also reduces its mechanical properties and service life.

[0004] The main methods in the prior art to reduce processing damage and defects include composite processing, adding support plates, various pre-processing work, and real-time processing during the processing process.

[0005] The inventors found that the existing composite material processing equipment has the following problems:

[0006] The equipment for various types of composite processing is complex and expensive, and some of the conditions for implementation are relatively harsh;

[0007] Various types of support devices can cause new types of damage and have poor applicability to complex-shaped composite workpieces;

[0008] Various pre-processing works increase the processing steps and reduce production efficiency. Summary of the invention

[0009] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a device for suppressing composite material drilling damage by using negative pressure, which can suppress composite material drilling damage while drilling without adding additional processing steps.

[0010] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0011] A device for suppressing composite material drilling damage by using negative pressure comprises a shell, the shell supports a tool holder, the tool holder is used to install a hollow drill, the hollow drill is exposed outside the shell, the tool holder drives the hollow drill to rotate relative to the shell, the shell is separately connected to a vacuum generator and an air generator, the shell is hollow, the tool holder is connected to the inside of the shell and the inside of the hollow drill, when the vacuum generator is working, the air at the hollow drill is extracted through the shell and the tool holder to provide a resistance to offset the feed force to avoid drilling damage to the composite workpiece, and the air generated by the air generator when working is used to blow away the removed material at the hollow drill.

[0012] In the device for suppressing drilling damage of composite materials by using negative pressure as described above, the vacuum generator and the air generator are respectively connected to the controller, and the controller determines the maximum working power of the vacuum generator when it is working according to the maximum pressure value inside the hollow drill.

[0013] In the device for suppressing composite material drilling damage by using negative pressure as described above, the controller determines the maximum force magnitude of the cut material entering the hollow drill according to the feed force magnitude provided by the hollow drill and the force magnitude provided by the interlayer bonding force of the composite workpiece, and determines the maximum pressure value inside the hollow drill according to the maximum force magnitude of the cut material entering the hollow drill, the atmospheric pressure and the inner diameter of the hollow drill.

[0014] In the device for suppressing drilling damage of composite materials by using negative pressure as described above, the tool holder is connected to a rotary power source, the rotary power source is connected to the controller, a pressure sensor is provided at one end of the tool holder away from the hollow drill, the pressure sensor is connected to the controller, and when the hollow drill contacts the composite workpiece, the controller controls the vacuum generator to start when receiving data changes detected by the pressure sensor.

[0015] In the device for suppressing drilling damage of composite materials by using negative pressure as described above, a first gas pressure sensor is arranged in the hollow part of the tool holder to obtain the gas pressure inside the tool holder, and a second gas pressure sensor is arranged at the outlet pipe of the air generator, and the first gas pressure sensor and the second gas pressure sensor are respectively connected to the controller separately.

[0016] In the device for suppressing drilling damage of composite materials by using negative pressure as described above, a pressure regulating component is arranged at the shell, and the pressure regulating component includes a pressure regulating bolt arranged through the shell, a spring is arranged between the pressure regulating bolt and the shell, and a pressure regulating nut is arranged at the part of the pressure regulating bolt located at the shell, and the pressure regulating nut is adjusted at the pressure regulating bolt to compress or relax the spring.

[0017] In the device for suppressing composite material drilling damage by using negative pressure as described above, the tool holder is provided with a T-shaped opening, the transverse section of the T-shaped opening is connected to the interior of the shell, and the vertical section of the T-shaped opening is detachably connected to the hollow drill.

[0018] In a second aspect, the present invention further provides a machine tool, which uses a first workbench and a second workbench, wherein the first workbench is used to support a composite workpiece, and the second workbench is used to set up a device for suppressing composite drilling damage using negative pressure, and the second workbench is arranged perpendicular to the first workbench, and the second workbench is located on one side of the first workbench.

[0019] In the machine tool as described above, the first workbench includes a multi-directional motion mechanism, and the multi-directional motion mechanism is connected to the work surface;

[0020] The shell is fixed in the outer shell, and the outer shell is installed at the second workbench through a vertical linear motion mechanism.

[0021] In a second aspect, the present invention also provides a working method of a device for suppressing composite material drilling damage using negative pressure, including the following contents:

[0022] Install the core drill in the tool holder;

[0023] After the hollow drill is close to the composite workpiece, the vacuum generator is started. When the vacuum generator is working, the air at the hollow drill is extracted through the housing and the tool holder, so that negative pressure is formed at the hollow drill. The negative pressure acts on the removed material to generate a force opposite to the drilling feed direction, so that the removed material pulls the unprocessed material, that is, generates a resistance to offset the feed force to avoid drilling damage;

[0024] During the drilling process of a composite workpiece, the removed material enters the hollow drill;

[0025] The hollow drill moves in a direction away from the composite workpiece, and after moving a set distance, the composite workpiece is removed;

[0026] The air generator works, and the air generated by the air generator blows out the removed material at the core drill.

[0027] The beneficial effects of the present invention are as follows:

[0028] 1) The present invention is provided with a vacuum generator and an air generator through the setting of the entire device. When the vacuum generator is working, the air at the hollow drill is sucked through the shell and the tool holder to make the hollow drill have a negative pressure, thereby providing a resistance to offset the feed force to the composite workpiece to avoid drilling damage, and effectively offset the damage caused by the feed force while drilling. The air generated by the air generator when working is used to blow away the removed material at the hollow drill; the overall structure is simple, no additional pretreatment process is required, and the processing efficiency is improved.

[0029] 2) The controller of the present invention determines the working power of the vacuum generator according to the bonding force between the composite workpieces to ensure the negative pressure at the hollow drill so that the generated resistance is sufficient to offset the feed force and fully reduce the damage to the composite workpiece.

[0030] 3) In the present invention, a pressure sensor is arranged at the tool holder, and the pressure sensor is connected to the controller. When the hollow drill contacts the composite workpiece, the data detected by the pressure sensor will change. When the controller receives the data change detected by the pressure sensor, it controls the vacuum generator to start, thereby suppressing the drilling damage to the composite workpiece. This method is also convenient for cooperating with other processing environments, and the process and device are highly compatible.

[0031] 4) The present invention provides a machine tool, which is provided with a first worktable and a second worktable, wherein the first worktable is connected to a multi-directional motion mechanism to drive a composite workpiece to perform multi-directional motion, the first worktable is used to support the composite workpiece, and the second worktable is used to support a shell, so that a hollow drill can process the composite workpiece.

[0032] 5) The method provided by the present invention does not need to consider the shape of the supported surface and the fixing method of the support; compared with the existing composite processing method, there is no need to perform complex structural design on the processing equipment; by using a simpler process based on the nature of the hollow drill drilling process, the drilling damage of the composite workpiece is suppressed; the process can utilize the air compressor provided by the machining center and only requires an external vacuum pump, thereby reducing the complexity of the processing; the process does not require the addition of additional pretreatment steps, thereby improving the processing efficiency; the process can adapt to the underwater processing environment and is easy to reduce other negative impacts during the processing process. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0034] Figure 1 Schematic diagram of a device for suppressing composite material drilling damage by using negative pressure according to one or more embodiments of the present invention.

[0035] Figure 2 It is a schematic diagram of the working principle of a hollow drill in a device for suppressing composite material drilling damage using negative pressure according to one or more embodiments of the present invention.

[0036] Figure 3 It is a schematic diagram of a shell supporting a tool holder in a device for suppressing composite material drilling damage by using negative pressure according to one or more embodiments of the present invention.

[0037] Figure 4 The present invention is a cross-sectional view of a housing supporting a tool holder in a device for suppressing composite material drilling damage using negative pressure according to one or more embodiments of the present invention.

[0038] In the figure: the distances or sizes between parts are exaggerated to show the positions of various parts, and the schematic diagram is for reference only.

[0039] Among them: 1-hollow drill, 2-composite workpiece, 3-vacuum pump, 41-pressure regulating component, 411-spring, 412-pressure regulating bolt, 413-pressure regulating nut, 42-housing, 43-tool holder, 5-second workbench, 6-gas pipeline, 7-air compressor, 8-second valve, 9-first valve, 10. First workbench, 11. housing. DETAILED DESCRIPTION

[0040] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0041] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless otherwise explicitly stated in the present invention, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "include" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof;

[0042] As introduced in the background technology, the prior art has the problem that composite materials are easily damaged during composite material processing. In order to solve the above technical problem, the present invention proposes a device for suppressing composite material drilling damage by using negative pressure.

[0043] Embodiment 1

[0044] In a typical embodiment of the present invention, reference is made to Figure 1 As shown, a device for suppressing composite material drilling damage by using negative pressure includes a shell 42, the shell 42 supports a tool holder 43, the tool holder 43 is used to install a hollow drill 1, the hollow drill 1 is exposed from the shell, the tool holder 43 drives the hollow drill 1 to rotate relative to the shell 42, the shell 42 is separately connected to a vacuum generator and an air generator, the shell 42 is hollow, the tool holder 43 is connected to the inside of the shell 42 and the inside of the hollow drill, when the vacuum generator is working, the air at the hollow drill 1 is exhausted through the shell 42 and the tool holder to provide a resistance to offset the feed force to the composite workpiece 2 to avoid drilling damage, and the air generated by the air generator when working is used to blow away the removed material at the hollow drill.

[0045] In this embodiment, the housing 42 is connected to the gas pipeline 6, and the other end of the gas pipeline 6 is bifurcated, one end of which is connected to the vacuum generator, and the other end of which is connected to the air generator.

[0046] The vacuum generator is provided with a first valve 9, and the air generator is provided with a second valve 8, and the first valve 9 and the second valve 8 are respectively connected to the controller;

[0047] Explain from the perspective of mechanics, first assume that the inner diameter of the hollow drill 1 is r 1 , the outer diameter of the hollow drill 2 is r 2 The radius of the circle of the bonding force between the two layers of the composite workpiece is r 3 The range of action of the bonding force between the layers of the composite workpiece is concentric with the hollow drill 1, so it can be known that r 1 <r 2 <r 3 ; At the same time, it is assumed that the load distribution function of the interlayer bonding force within the action range is p 1 (r); the pressure inside the hollow drill is p 1 , atmospheric pressure is p 0 ; The feed force provided by the hollow drill 1 is F 3 , whose value can be obtained according to the preset parameters, or directly measured by the force measuring device (pressure sensor set at the bottom of the hollow drill), so the force F provided by the interlayer bonding force of the composite workpiece can be obtained. 1 for:

[0048]

[0049] Among them, dA is the infinitesimal area under force, dA=dπr 2 =2πrdr, r is the distance from the infinitesimal element of the force area to the center of the circle;

[0050] The force F of the cut material entering the hollow drill 2 for:

[0051]

[0052] Therefore, it can be known that the resultant force F on the composite workpiece 2 is:

[0053] F=F 3 -F 1 -F 2

[0054] Therefore, it can be seen that if F>0, drilling delamination damage will occur, otherwise drilling delamination damage will not occur.

[0055] Compared with traditional drilling, the force F of the cut material entering the hollow drill is 2 To offset the feed force F3 , thereby reducing the resultant force F on the composite workpiece and suppressing delamination damage.

[0056] In this way, considering that the working power of the vacuum generator is proportional to the pressure inside the hollow drill, the controller determines the maximum force of the cut material entering the hollow drill according to the difference between the feed force provided by the hollow drill and the force provided by the interlayer bonding force of the composite workpiece, determines the maximum pressure value inside the hollow drill according to the maximum force of the cut material entering the hollow drill, the atmospheric pressure and the inner diameter of the hollow drill, and determines the maximum working power of the vacuum generator when it is working according to the determined maximum pressure value inside the hollow drill.

[0057] It is easy to understand that the tool holder 43 passes through one end of the housing 42 and is connected to the rotary power source, the rotary power source is a rotary motor, the rotary power source 43 is fixed in the housing 11, the rotary power source 43 is connected to the controller, and a pressure sensor is arranged at one end of the tool holder 43 away from the hollow drill, the pressure sensor is connected to the controller, when the hollow drill contacts the composite workpiece 2, the controller receives the data detected by the pressure sensor and controls the vacuum generator to start;

[0058] Considering that the tool holder needs to be connected to the rotary power source, the pressure sensor is arranged between the rotary power source and the housing 11. Under normal circumstances, the rotary power source is in contact with the housing. At this time, the pressure sensor sends the detected data to the controller. When the hollow drill contacts the composite workpiece 2 and starts drilling, the value of the pressure sensor changes due to the transmission of force and is sent to the controller. After receiving the value, the controller controls the start of the vacuum generator.

[0059] It needs to be explained that the tool holder 43 can be rod-shaped, and the tool holder 43 is arranged through the shell 42. The tool holder 43 is provided with a T-shaped opening, the transverse section of the T-shaped opening is connected with the interior of the shell 42, the vertical section of the T-shaped opening is a threaded hole, and the vertical section of the T-shaped opening is detachably connected to the hollow drill, and the outer diameter of one side of the hollow drill connected to the T-shaped opening is smaller than the outer diameter of the other side of the hollow drill.

[0060] It can be understood that a first gas pressure sensor is set in the vertical section of the T-shaped opening of the tool holder to obtain the gas pressure inside the tool holder 43, and a second gas pressure sensor is set in the outlet pipe of the air generator to obtain the gas pressure at the second outlet pipe. The first gas pressure sensor and the second gas pressure sensor are separately connected to the controller so that the controller can monitor the gas pressure at the first outlet pipe and the second outlet pipe. The pressure in the vertical section of the T-shaped opening of the tool holder is lower than the air pressure inside the hollow drill. The controller can determine the pressure inside the hollow drill according to the pressure at the vertical section of the T-shaped opening, the inner diameter of the vertical section of the T-shaped opening and the inner diameter of the hollow drill. If the pressure is greater than the maximum value of the internal pressure of the hollow drill, the controller needs to turn off the vacuum generator. When the second gas pressure sensor is greater than the set value, the air generator is turned off.

[0061] It is easy to understand that the controller is a PLC controller or other types of controllers, and the controller can also be a machine tool controller. The controller is connected to a display screen, and the data detected by the pressure sensor and the two gas pressure sensors can be displayed through the display screen.

[0062] In this embodiment, in order to prevent the instantaneous negative pressure from being too large during the drilling process, which may cause other damage defects, a pressure regulating component 41 is provided at the shell. Figure 3 and Figure 4 As shown, the pressure regulating component 41 includes a pressure regulating bolt 412 that passes through the shell, a spring 411 is arranged between the pressure regulating bolt 412 and the shell 42, and a pressure regulating nut 413 is arranged at the part of the shell where the pressure regulating bolt 412 is located. The pressure regulating nut 413 is adjusted at the pressure regulating bolt 412 to compress or relax the spring. If the first pressure sensor detects that the instantaneous negative pressure is greater than the set value, the controller receives it and displays it on the display to facilitate the staff to find it in time and turn the pressure regulating nut in time; of course, the limit of the negative pressure threshold in the shell is changed by screwing the pressure regulating nut 413 to adapt to the processing of different types of composite workpieces 2.

[0063] Specifically, rotating the pressure-adjusting nut 413 toward the direction close to the shell 42 can compress the spring 411. At this time, the force required to pull the bolt to form negative pressure increases, which is suitable for working conditions where rapid feeding causes large thrust or large bonding force of the laminate; conversely, the force required to pull the pressure-adjusting bolt to form negative pressure is small, which is suitable for working conditions where the thrust or interlayer bonding force is small.

[0064] In addition, in some examples, the pressure regulating component 41 is a pressure regulating valve, which is connected to the controller, and a third gas pressure sensor is arranged in the shell. When the third gas pressure sensor detects that the internal pressure of the shell is greater than the set value, it sends a signal to the controller, and the controller controls the pressure regulating valve to open for pressure regulation; moreover, with the change of air tightness during processing and the limitation of the pressure regulating valve, the internal pressure of the hollow drill gradually fluctuates around the set value. At this time, by controlling the working mode of the vacuum generator or by changing the pressure relief mode of the pressure regulating valve 41, the negative pressure value fluctuates more, so as to obtain an effect similar to mechanical vibration, thereby enhancing the ability to cut the fibers of the composite workpiece 2.

[0065] Among them, the vacuum generator is a vacuum pump 3, and the air generator is an air compressor 7. The vacuum pump 3 and the air compressor 7 are both traditional and common general equipment and will not be described in detail.

[0066] The device provided in this embodiment refers to Figure 2 As shown, when the vacuum generator is working, a negative pressure is formed inside the cavity of the hollow drill through the setting of the shell and the tool holder. The negative pressure is equivalent to applying a resistance force opposite to the feed direction to the cut material entering the hollow drill. The resistance force simultaneously pulls the uncut material. Part of the resistance force can partially offset the thrust generated by the machining feed, thereby partially offsetting the feed thrust and suppressing the delamination and other damage problems between the machined material layer and the unmachined material layer.

[0067] Embodiment 2

[0068] This embodiment provides a machine tool, referring to Figure 1 As shown, a first workbench 10 and a second workbench 5 are used. The first workbench 10 is fixed to a machine tool frame. The first workbench 10 is used to support a composite workpiece 2. The second workbench 5 is used to set a device for suppressing drilling damage of a composite workpiece 2 by using negative pressure as described in Example 1. The second workbench 5 is vertically arranged with respect to the first workbench 10, and the second workbench 5 is located on one side of the first workbench 10.

[0069] It is easy to understand that the first workbench 10 includes a multi-directional motion mechanism, which is connected to the work surface; the shell 42 is fixed in the outer shell 11, the cross-section of the outer shell 11 is rectangular, and the outer shell 11 is installed on the machine tool frame through a vertical linear motion mechanism, and the vertical linear motion mechanism is a Z-direction linear guide. One side of the outer shell 11 is fixed to the machine tool frame through the Z-direction linear guide, and the Z-direction linear guide can drive the outer shell 11 to move in the vertical direction.

[0070] Specifically, the first workbench 10 includes an X-direction linear guide rail, and the X-direction linear guide rail is provided with two locations to ensure the stability of the X-direction linear guide rail. The X-direction linear guide rail supports the Y-direction linear guide rail, and the Y-direction linear guide rail is also provided with two locations to ensure the stability of the Y-direction linear guide rail. The Y-direction linear guide rail is connected to the work surface.

[0071] Embodiment 3

[0072] A working method of a device for suppressing drilling damage of a composite workpiece 2 by using negative pressure, comprising the following contents:

[0073] Install the hollow drill 1 with a through hole to the tool holder 43, adjust and clamp the tool holder 43, connect the housing 42 to the gas pipeline 6, and the gas pipeline 6 is connected to the vacuum pump 3 and the air compressor 7 at the same time. The housing 42 is set in the shell, and the shell is fixed to the second workbench 5. Twist the pressure regulating nut 413 and rotate the pressure regulating bolt 412 to compress or relax the pressure regulating spring 411 to adjust the working threshold of the pressure regulating valve 41;

[0074] The machine tool controller controls the second worktable 5 and the rotating power source to drive the hollow drill 1 to work. The hollow drill 1 is close to the composite workpiece 2, and the vacuum pump 3 is started to start processing. Along with the feeding, the negative pressure formed generates a resistance to offset the feeding force.

[0075] The machine tool controller opens the first valve 9 and closes the second valve 8. The hollow drill 1 continues to approach the composite workpiece 2. After contacting the surface of the composite workpiece 2, the machine tool controller obtains this information based on the data change of the pressure sensor. After obtaining the information, the vacuum pump 3 is started to extract the gas in the internal cavity of the hollow drill 1, so that the internal air pressure of the hollow drill 1 is lower than the atmospheric pressure, thereby forming a negative pressure. The atmospheric pressure presses the material into the hollow drill, that is, the negative pressure exerts a force opposite to the drilling feed direction on the removed material (the part entering the cavity of the hollow drill 1). During the machining process (from the time when drilling starts to contact the surface of the composite workpiece 2 to before the drill completely penetrates the composite workpiece 2), the removed material always pulls the unprocessed material (that is, the material layer that has not been drilled by the drill) along the direction of action of the force, thereby partially offsetting the thrust generated by drilling along the feed direction.

[0076] The process of generating and regulating the negative pressure is a parallel step with the drilling process. The process of generating and regulating the negative pressure starts after the drilling process and ends before the drilling process.

[0077] Finally, after the processing is completed and the hollow drill is controlled to retract and reach the designated chip removal location, the vacuum pump 3 is turned off and the air compressor 7 is turned on to discharge the removed material inside the hollow drill;

[0078] Among them, the working mode of the pressure regulating valve 41 is that when the pressure difference between the air pressure in the cavity and the atmospheric pressure is too large, that is, when the negative pressure is greater than the threshold, the pressure regulating bolt 412 on the pressure regulating valve 41 is pulled to move inside the cavity to reduce the pressure difference, and returns to the initial state when the negative pressure is less than the threshold; and adjusting the pressure threshold is mainly to screw the pressure regulating nut 413 to compress the pressure regulating spring 411, and screwing it in the direction close to the shell will increase the pressure threshold, and vice versa.

[0079] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A device for suppressing composite material drilling damage by using negative pressure, characterized in that: The utility model comprises a shell, which supports a tool holder, and the tool holder is used to install a hollow drill. The hollow drill is exposed outside the shell, and the tool holder drives the hollow drill to rotate relative to the shell. The shell is separately connected with a vacuum generator and an air generator, and the shell is hollow. The tool holder is connected with the inside of the shell and the inside of the hollow drill. When the vacuum generator is working, the air at the hollow drill is extracted through the shell and the tool holder to provide a resistance to offset the feed force to the composite workpiece to avoid drilling damage. The air generated by the air generator when working is used to blow away the removed material at the hollow drill.

2. The device for suppressing composite material drilling damage by using negative pressure according to claim 1, characterized in that: The vacuum generator and the air generator are connected to the controller respectively, and the controller determines the maximum working power of the vacuum generator when it is working according to the maximum pressure value inside the hollow drill.

3. The device for suppressing composite material drilling damage by using negative pressure according to claim 2, characterized in that: The controller determines the maximum force magnitude of the cut material entering the hollow drill according to the feed force magnitude provided by the hollow drill and the force magnitude provided by the interlayer bonding force of the composite workpiece, and determines the maximum pressure value inside the hollow drill according to the maximum force magnitude of the cut material entering the hollow drill, the atmospheric pressure and the inner diameter of the hollow drill.

4. The device for suppressing composite material drilling damage by using negative pressure according to claim 2, characterized in that: The tool holder is connected to a rotary power source, which is connected to the controller. A pressure sensor is provided at one end of the tool holder away from the hollow drill, which is connected to the controller. When the hollow drill contacts the composite workpiece, the controller receives data changes detected by the pressure sensor and controls the vacuum generator to start.

5. The device for suppressing composite material drilling damage by using negative pressure according to claim 2, characterized in that: A first gas pressure sensor is arranged in the hollow part of the tool holder to obtain the gas pressure inside the tool holder, and a second gas pressure sensor is arranged at the outlet pipe of the air generator. The first gas pressure sensor and the second gas pressure sensor are separately connected to the controller.

6. The device for suppressing composite material drilling damage by using negative pressure according to claim 1, characterized in that: A pressure regulating component is arranged at the shell, and the pressure regulating component includes a pressure regulating bolt arranged through the shell, a spring is arranged between the pressure regulating bolt and the shell, and a pressure regulating nut is arranged at the part of the pressure regulating bolt located at the shell, and the pressure regulating nut is adjusted at the pressure regulating bolt to compress or relax the spring.

7. The device for suppressing composite material drilling damage by using negative pressure according to claim 1, characterized in that: The tool holder is provided with a T-shaped opening, the transverse section of the T-shaped opening is communicated with the interior of the shell, and the vertical section of the T-shaped opening is detachably connected with the hollow drill.

8. A machine tool, characterized in that: A first workbench and a second workbench are used, the first workbench is used to support the composite workpiece, the second workbench is used to set a device for suppressing composite drilling damage using negative pressure as described in any one of claims 1 to 7, the second workbench is vertically arranged to the first workbench, and the second workbench is located on one side of the first workbench.

9. A machine tool according to claim 8, characterized in that: The first workbench includes a multi-directional motion mechanism connected to the work surface; The shell is fixed in the outer shell, and the outer shell is installed at the second workbench through a vertical linear motion mechanism.

10. A working method of a device for suppressing composite material drilling damage by using negative pressure according to any one of claims 1 to 7, characterized in that: It includes the following: Install the core drill in the tool holder; After the hollow drill is close to the composite workpiece, the vacuum generator is started. When the vacuum generator is working, the air at the hollow drill is extracted through the housing and the tool holder, so that negative pressure is formed at the hollow drill. The negative pressure acts on the removed material to generate a force opposite to the drilling feed direction, so that the removed material pulls the unprocessed material, that is, generates a resistance to offset the feed force to avoid drilling damage; During the drilling process of a composite workpiece, the removed material enters the hollow drill; The hollow drill moves in a direction away from the composite workpiece, and after moving a set distance, the composite workpiece is removed; The air generator works, and the air generated by the air generator blows out the removed material at the core drill.

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