Drilling method and drilling system based on ultrasonic assisted thermoplasticity

Abstract

The embodiment of the application belongs to the technical field of thermoplastic drilling processing, and relates to a drilling method based on ultrasonic-assisted thermoplastic and a drilling system. The drilling method is applied to the drilling system based on ultrasonic-assisted thermoplastic, and the method comprises the following steps: controlling the drilling system to rotate at a preset rotating speed and ultrasonic vibration at a preset amplitude; and controlling the drilling system to move towards a workpiece to drill the workpiece. The method can reduce the processing force of the drilling system, facilitate chip removal in the hole forming process, and prolong the service life of the thermoplastic drill.

Description

Technical Field

[0001] The present application relates to the technical field of thermoplastic drilling, and in particular to a drilling method and a drilling system based on ultrasonic-assisted thermoplastic drilling. Background Art

[0002] The hole-forming process typically involves using a flow drill to create the desired hole and cushion bushing in thin sheet metal, thin-walled tubing, or composite workpieces. This method utilizes friction between a high-speed rotating, sharp-edged flow drill and the workpiece, generating significant heat and causing the workpiece to melt. A portion of the workpiece material follows the drill tip downward, forcing the hole and forming a downward-facing bushing, while another portion of the material flows upward along the drill stem, forming an upward-facing bushing. This method achieves excellent results in machining low-melting-point metal materials, such as ordinary steel, aluminum alloys, copper, and stainless steel, replacing the nut welding process for thin-walled metal parts. However, flow drilling is primarily targeted at machining ordinary metals, and most flow drills use traditional or modified-edged flow drills with diameters ranging from 4 to 20 mm. Traditional flow drills are difficult to machine due to their high hardness, wear resistance, and high-temperature resistance, such as titanium alloys.

[0003] Specifically, traditional flow drills require frictionally heating the workpiece to a near-molten state to facilitate expansion and flow. If the temperature is insufficient, the workpiece's base material has poor fluidity, resulting in a tight fit with the flow drill, which can easily cause the flow drill to stick. For example, workpieces such as titanium alloys have low density, high strength, excellent wear resistance, and high-temperature resistance. Using the traditional flow drill principle to soften the workpiece material to a near-molten state, flow drilling in titanium alloys is difficult. Firstly, due to titanium alloy's low deformation coefficient, poor thermal conductivity, and high chemical activity, excessive cutting forces can occur during flow drilling, making it easy for titanium alloy debris to stick to the flow drill, increasing wear and significantly reducing its lifespan. Furthermore, titanium alloys have a high melting point, requiring the flow drill to generate significant frictional heat to soften the material during heat transfer. If the temperature is not high enough, the flow drill can easily stick to the tool, further exacerbating wear. Especially when processing holes with smaller diameters, the hot melt drill has a small diameter and low strength and rigidity, and is very prone to wear and breakage during hot melting. Summary of the Invention

[0004] The purpose of the embodiments of the present application is to propose a drilling method and a drilling system based on ultrasonic-assisted thermoplasticity to reduce the processing force of the drilling system, facilitate chip removal, and extend the life of the thermoplastic drill of the drilling system.

[0005] In order to solve the above technical problems, the present application provides a drilling method based on ultrasound-assisted thermoplasticity, which adopts the following technical solutions:

[0006] The drilling method is applied to a drilling system based on ultrasonic assisted thermoplasticity, and the method comprises:

[0007] Controlling the drilling system to rotate at a preset speed and to perform ultrasonic vibration at a preset amplitude;

[0008] The drilling system is controlled to move toward a workpiece to drill a hole in the workpiece.

[0009] Furthermore, the drilling system includes a machine tool table carrying the workpiece and a thermoplastic drill;

[0010] The step of controlling the drilling system to rotate at a preset speed and to perform ultrasonic vibration at a preset amplitude further includes:

[0011] The machine tool worktable and / or the thermoplastic drill are controlled to rotate at the preset speed, and the machine tool worktable and / or the thermoplastic drill are controlled to perform ultrasonic vibration at the preset amplitude.

[0012] Furthermore, the step of controlling the machine tool worktable and / or the thermoplastic drill to perform ultrasonic vibration at the preset amplitude further includes:

[0013] The machine tool table and / or the thermoplastic drill are controlled to ultrasonically vibrate at a preset amplitude relative to a preset direction of the workpiece, wherein the preset direction includes at least one group of the following directions: an up-down direction, a left-right direction, and a front-back direction relative to the workpiece.

[0014] Furthermore, the drilling system includes a machine tool table carrying the workpiece and a thermoplastic drill;

[0015] The step of controlling the drilling system to move toward the workpiece includes:

[0016] The thermoplastic drill is controlled to move toward the workpiece at a preset moving speed, or the machine tool worktable is controlled to move toward the thermoplastic drill at the preset moving speed, so as to drill a hole in the workpiece.

[0017] Furthermore, the preset rotation speed range is 100 rpm-10,000 rpm, the preset amplitude range is 0.1 μm-20 μm, and the preset moving speed range is 10 mm / min-2,000 mm / min.

[0018] Furthermore, the diameter of the thermoplastic drill is 0.1 mm to 20 mm, wherein the diameter of the thermoplastic drill refers to the diameter of the structure of the thermoplastic drill adapted to the hole diameter.

[0019] Furthermore, the preset rotation speed, the preset amplitude and the preset moving speed are selected to different values ​​according to the diameter of the thermoplastic drill and / or the workpiece;

[0020] The preset moving speed is positively correlated with the preset rotation speed and the preset amplitude respectively.

[0021] Furthermore, the thermoplastic drill includes at least two processing parts;

[0022] The method further comprises:

[0023] When the workpiece is processed at different processing locations, at least one of the preset rotation speed, the preset amplitude, and the preset moving speed is adjusted.

[0024] In order to solve the above technical problems, the embodiments of the present application further provide a drilling system based on ultrasound-assisted thermoplasticity, which adopts the following technical solutions:

[0025] The drilling system includes a machine tool table, a thermoplastic drill, a tool holder, a vibration control device, a rotation control device, and a movement control device, wherein:

[0026] The machine tool worktable is used to carry the workpiece;

[0027] The thermoplastic drill is connected to the tool handle, and the tool handle is further connected to the vibration control device, and is used to perform ultrasonic vibration with a preset amplitude under the control of the vibration control device, and drive the thermoplastic drill to perform ultrasonic vibration with the preset amplitude;

[0028] The machine tool worktable and / or tool handle are further connected to the rotation control device and the movement control device, and the rotation control device and the movement control device are used to respectively control the machine tool worktable and / or the tool handle to rotate and move at a preset speed, so as to control the relative rotation and movement of the machine tool worktable and the thermoplastic drill to drill holes in the workpiece.

[0029] Furthermore, the diameter of the thermoplastic drill is 0.1 mm to 20 mm, wherein the diameter of the thermoplastic drill refers to the diameter of the structure of the thermoplastic drill adapted to the hole diameter.

[0030] Compared with the prior art, the embodiments of the present application have the following advantages: This application proposes a drilling method and system based on ultrasonic-assisted thermoplastic drilling. The method is applied to an ultrasonic-assisted thermoplastic drilling system and includes: controlling the drilling system to rotate at a preset speed and ultrasonically vibrate at a preset amplitude; and controlling the drilling system to move toward a workpiece to drill a hole in the workpiece. This method addresses the problems of excessive cutting force, flow drill sticking, and flow drill wear that exist with conventional flow drills when machining hard, wear-resistant, and high-temperature resistant materials, such as titanium alloys. The drilling system of the present application generates ultrasonic vibrations at a preset amplitude. This effectively reduces cutting forces during the drilling process, thereby reducing the processing effort and wear of the thermoplastic drill. Furthermore, because the drilling system is constantly in a high-frequency ultrasonic vibration state, it facilitates chip removal from the thermoplastic drill during the drilling process, preventing adhesion between the thermoplastic drill and the workpiece substrate, thereby preventing the drill from breaking. Furthermore, because the ultrasonic vibration increases the rigidity of the drilling system, the machining process becomes more stable, resulting in high-quality hole walls and bushings when drilling difficult-to-machine materials (such as titanium alloys). Thanks to the high-frequency ultrasonic vibration of the thermoplastic drill after the vibration is applied, adhesion between the thermoplastic drill and the workpiece substrate is avoided. The ultrasonic vibration-assisted drilling system, when rotating at high speed, does not need to reach the melting temperature of the workpiece, such as titanium alloy, but only the softening and plastic deformation temperature to perform the hot drilling process, significantly reducing the machining temperature and extending the life of the thermoplastic drill. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the solutions in this application, a brief introduction will be given below to the drawings required for use in the description of the embodiments of this application. Obviously, the drawings described below are some embodiments of this application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0032] Figure 1 1 is a schematic structural diagram of an embodiment of a drilling system based on ultrasound-assisted thermoplasticity of the present application;

[0033] Figure 2 It is a flow chart of a drilling method based on ultrasound-assisted thermoplasticity according to an embodiment of the present application. DETAILED DESCRIPTION

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used in the description herein is for describing particular embodiments only and is not intended to be limiting of the application. Unless otherwise defined, all terms used herein, including technical and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description herein is for describing particular embodiments only and is not intended to be limiting of the application. The terms "comprises", "comprising", "includes", "including", "has", "having" and the like are used in the detailed description and in the claims to mean that the stated features, steps, characteristics, and the like are included, but not excluded. The terms "first", "second", and the like, used in the description and in the claims, are used for distinguishing between similar objects and are not necessarily used in a sequence.

[0035] Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily mutually exclusive of one another. As will be apparent to those of ordinary skill in the art, embodiments described herein can be combined with other embodiments.

[0036] In order to make the technical personnel in the art better understand the scheme of the application, the technical solutions in the embodiments of the application will be clearly and completely described below with reference to the drawings.

[0037] Reference will be made to Figure 1 , Figure 1 A structural schematic diagram of one embodiment of the ultrasonic-assisted thermoplastic drilling system of the application is shown. As shown in Figure 1 , the drilling system 10 includes a machine tool worktable 101, a thermoplastic drill 103, a vibration control device 104, a tool holder 105, a rotation control device 106, and a movement control device 107. Among them, the machine tool worktable 101 and the thermoplastic drill 103 are oppositely arranged, and a workpiece 102 is arranged on the machine tool worktable 101. The thermoplastic drill 103 is connected to the tool holder 105, and the tool holder 105 is further connected to the vibration control device 104, which is used to control the ultrasonic vibration of the thermoplastic drill 103 at a preset amplitude under the control of the vibration control device 104. That is, the vibration control device 104 controls the ultrasonic vibration of the thermoplastic drill 103 by controlling the ultrasonic vibration of the tool holder 105, so as to provide an ultrasonic vibration effect on the workpiece 102. In a specific application, the vibration control device 104 can be an ultrasonic vibration control device. Among them, the diameter of the thermoplastic drill is 0.1mm-20mm, and the diameter of the thermoplastic drill refers to the diameter of the structure that is matched with the hole diameter.

[0038] The machine tool table 101 and / or the tool handle 105 are further connected to a rotation control device 106 and a movement control device 107. The rotation control device 106 and the movement control device 107 are used to respectively control the machine tool table 101 and / or the tool handle 105 to rotate and move at a preset speed, so as to control the relative rotation and movement of the machine tool table 101 and the thermoplastic drill 103 to drill a hole in the workpiece 102. Specifically, in one embodiment, Figure 1 As shown, the machine tool table 101 can be connected to a motion control device 107, and the tool holder 105 can be connected to a rotation control device 106. Based on this, under the control of the motion control device 107, the machine tool table 101 moves toward the thermoplastic drill 103, thereby driving the workpiece 102 toward the thermoplastic drill 103. Under the control of the rotation control device 106, the tool holder 105 rotates at a preset speed, thereby driving the thermoplastic drill 103 to rotate at a preset speed. Combined with the vibration described above, the thermoplastic drill 103 undergoes high-speed rotation and high-frequency ultrasonic vibration. Through this high-speed rotation and high-frequency ultrasonic vibration, the workpiece 102 is drilled to form the desired hole.

[0039] In other embodiments, the machine tool worktable 101 may be further connected to a rotation control device 106 and a movement control device 107 , that is, the machine tool worktable 101 rotates and moves relative to the thermoplastic drill 103 under the control of the rotation control device 106 and the movement control device 107 .

[0040] In other embodiments, the tool handle 105 may be further connected to the rotation control device 106 and the movement control device 107. That is, the tool handle 105 rotates and moves relative to the machine tool worktable 101 under the control of the rotation control device 106 and the movement control device 107, so as to drive the thermoplastic drill 103 to rotate and move relative to the machine tool worktable 101.

[0041] In other embodiments, the machine tool table 101 can be further connected to a rotation control device 106, and the tool handle 105 can be connected to a movement control device 107, thereby similarly achieving the effect of relative rotation and movement between the machine tool table 101 and the thermoplastic drill 103. Therefore, the present application incorporates a vibration control device 104 in an ultrasound-assisted thermoplastic drilling system, enabling the thermoplastic drill 103 to generate ultrasonic vibrations in addition to rotation. This combination of rotation and ultrasonic vibrations forms the desired hole in the workpiece 102. The addition of a vibration control system effectively reduces the cutting force of the thermoplastic drill 103 during drilling, thereby reducing wear on the thermoplastic drill 103. Secondly, since the drilling system 10 is in an ultrasonic vibration state, it facilitates chip removal during the hole forming process, avoids adhesion between the thermoplastic drill 103 and the base material of the workpiece 102, and thus effectively prevents the thermoplastic drill 103 from breaking; in addition, ultrasonic vibration can improve the rigidity of the drilling system 10, making the hole processing process more stable. When processing holes of difficult-to-process materials (such as titanium alloy), high-quality hole walls and bushings can be obtained; finally, the addition of ultrasonic vibration processing technology means that the drilling system does not need to reach the melting temperature of the workpiece 102, but only needs to reach its softening and plastic deformation temperature to implement the hot drilling process, which greatly reduces the processing temperature and is beneficial to extending the life of the thermoplastic drill 103.

[0042] This application is based on Figure 1 The ultrasonic-assisted thermoplastic drilling system 10 shown controls a thermoplastic drill 103 to form a desired hole on a workpiece 102 through the ultrasonic-assisted thermoplastic drilling method described below.

[0043] Please join us Figure 2 , Figure 2 FIG. 1 is a flow chart of a drilling method based on ultrasound-assisted thermoplasticity according to an embodiment of the present application. Figure 2 As shown, the method includes the following steps:

[0044] Step S1: controlling the drilling system 10 to rotate at a preset rotation speed and to perform ultrasonic vibration at a preset amplitude.

[0045] Step S2 : controlling the drilling system 10 to move toward the workpiece 102 to drill a hole in the workpiece 102 .

[0046] In this embodiment, the workpiece 102 is machined through the rotation and ultrasonic vibration of an ultrasonically assisted thermoplastic drilling system to form the desired hole in the workpiece 102. Ultrasonic vibration effectively reduces the cutting force of the thermoplastic drill during drilling, thereby reducing wear on the thermoplastic drill 103. Furthermore, the ultrasonic vibration of the drilling system 10 facilitates chip removal during the hole formation process, preventing adhesion between the thermoplastic drill 103 and the base material of the workpiece 102, thereby effectively preventing breakage of the thermoplastic drill 103. Furthermore, vibration enhances the rigidity of the drilling system 10, making the hole formation process more stable. This allows for high-quality hole walls and bushings when drilling difficult-to-machine materials (such as titanium alloys). Finally, the addition of ultrasonic vibration allows the drilling system to perform the hot drilling process without reaching the melting temperature of the workpiece 102, requiring only the softening and plastic deformation temperature. This significantly reduces the processing temperature and helps extend the life of the thermoplastic drill 103.

[0047] Step S1 specifically controls the machine tool table 101 and / or the thermoplastic drill 103 to ultrasonically vibrate at the preset amplitude. Specifically, by controlling the machine tool table 101 and / or the thermoplastic drill 103 to rotate at high speed to achieve a thermoplastic drilling state, the machine tool table 101 and / or the thermoplastic drill 103 are further controlled to perform high-frequency ultrasonic vibrations to assist the thermoplastic drilling process. Thus, the desired hole is formed through high-speed rotation and high-frequency ultrasonic vibrations. This solves problems associated with conventional hot melt drills when drilling holes in workpieces, such as excessive cutting force, tool sticking, and tool wear.

[0048] To enhance the effectiveness of ultrasonic vibration, the machine tool table 101 and / or the thermoplastic drill 103 may be controlled to ultrasonically vibrate at a predetermined amplitude in a predetermined direction relative to the workpiece 102, wherein the predetermined direction includes at least one of the following directions: up and down, left and right, and front and back relative to the workpiece 102. In other words, ultrasonic vibration causes the thermoplastic drill 103 to vibrate in at least one of the vertical, left and right, and front and back directions relative to the workpiece 102, thereby enhancing the effectiveness of ultrasonic vibration.

[0049] It should be understood that in actual applications, if conditions permit, the direction of ultrasonic vibration can be directly controlled so that the thermoplastic drill 103 vibrates in the vertical, horizontal, and front-to-back directions relative to the workpiece 102 to achieve maximum vibration amplitude, thereby improving chip removal during the hole formation process, reducing the temperature of the thermoplastic processing, preventing adhesion between the thermoplastic drill 103 and the workpiece 102, and extending the life of the thermoplastic drill 103.

[0050] The preset speed range may be 100 rpm to 10,000 rpm, and the preset amplitude range may be 0.1 μm to 20 μm. The speed and amplitude may vary depending on the material of the workpiece 102 and / or the diameter of the thermoplastic drill 103. The diameter of the thermoplastic drill 103 refers to the diameter of the structure of the thermoplastic drill 103 that matches the hole diameter. Typically, the thermoplastic drill 103 has at least two drilling structures from bottom to top, with the upper drilling structure matching the hole diameter. The ultrasonic amplitude can be controlled by the output power of the vibration control device 104, for example, by controlling the output power of the vibration control device 104 to 80%.

[0051] In one embodiment, step S1 can control the thermoplastic drill 103 to rotate at the preset speed and control the thermoplastic drill 103 to perform ultrasonic vibration at the preset amplitude. Figure 1 As shown, the vibration control device 104 is an ultrasonic power source. By rotating the tool handle 105, it controls the thermoplastic drill 103 to rotate at high speed, following the direction of the tool handle 105 around the machine tool spindle (i.e., the rotation control device 106). Simultaneously, the output power of the vibration control device 104 provides high-frequency ultrasonic vibrations, enabling the thermoplastic drill 103 to machine the workpiece 102 through rotation and ultrasonic vibration. It will be appreciated that during machining, the rotation and ultrasonic vibration of the thermoplastic drill 103 are relative to the workpiece 102. That is, in this embodiment, the machine tool table 101, which carries the workpiece 102, does not rotate or ultrasonically vibrate; only the thermoplastic drill 103 rotates and ultrasonically vibrates, resulting in relative motion between the thermoplastic drill 103 and the workpiece 102.

[0052] In another embodiment, step S1 may further control the machine tool worktable 101 to rotate at a preset speed and to ultrasonically vibrate at a preset amplitude. That is, the thermoplastic drill 103 does not rotate or ultrasonically vibrate, and the rotation and ultrasonic vibration of the machine tool worktable 101 drive the workpiece 102 to move relative to the thermoplastic drill 103, thereby achieving the effects of high-speed rotation to form thermoplastics and high-frequency ultrasonic vibration assistance.

[0053] In another embodiment, step S1 may further control the thermoplastic drill 103 and the machine tool table 101 to rotate at a preset speed, and control the machine tool table 101 and the thermoplastic drill 103 to ultrasonically vibrate at a preset amplitude. That is, the thermoplastic drill 103 and the machine tool table 101 both rotate and ultrasonically vibrate, and the combined rotation and ultrasonic vibration of the two achieve the preset rotational and ultrasonic vibration effects.

[0054] In another embodiment, step S1 may further control one of the thermoplastic drill 103 and the machine tool table 101 to rotate at a preset speed, and control the other of the thermoplastic drill 103 and the machine tool table 101 to perform ultrasonic vibrations at a preset amplitude. For example, the thermoplastic drill 103 may be controlled to rotate at a preset speed, and the machine tool table 101 may be controlled to perform ultrasonic vibrations at a preset amplitude; or the machine tool table 101 may be controlled to rotate at a preset speed, and the thermoplastic drill 103 may be controlled to perform ultrasonic vibrations at a preset amplitude.

[0055] The above describes various control methods for the rotation and ultrasonic vibration of the thermoplastic drill 103 and the machine tool table 101. In actual applications, different control methods can be selected based on actual needs. For example, different control methods can be selected based on different workpieces 102. For example, for workpieces 102 with high material density and large dimensions, the heavy weight makes it difficult to control the rotation and ultrasonic vibration of the machine tool table 101. In this case, the rotation and ultrasonic vibration of the thermoplastic drill 103 can be controlled to form holes in the workpiece 102. Alternatively, different control methods can be selected based on different hole requirements. For example, if a large number of holes are required, multiple thermoplastic drills 103 are required, and controlling multiple thermoplastic drills 103 simultaneously is difficult, the rotation and ultrasonic vibration of the machine tool table 101 can be controlled to drive the rotation and ultrasonic vibration of the workpiece 102, thereby coordinating the holes with the thermoplastic drills 103.

[0056] In this application, in addition to controlling the relative rotation and ultrasonic vibration of the thermoplastic drill 103 and the workpiece 102, it is also necessary to control the relative movement of the thermoplastic drill 103 and the workpiece 102. Specifically, at initial startup, a predetermined distance exists between the thermoplastic drill 103 and the workpiece 102. Therefore, after controlling the relative rotation and ultrasonic vibration of the thermoplastic drill 103 and the workpiece 102, the thermoplastic drill 103 is further controlled to move toward the workpiece 102, or the machine tool table 101 is controlled to move toward the thermoplastic drill 103, so that the thermoplastic drill 103 and the workpiece 102 come into contact. The high-speed relative rotation of the thermoplastic drill 103 and the workpiece 102 and the high-frequency ultrasonic vibration generate a large amount of heat in the workpiece 102, rapidly increasing its temperature and causing it to soften and plastically deform. Furthermore, the thermoplastic drill 103 is controlled to move toward the workpiece 102 at a preset moving speed, or the machine tool worktable 101 is controlled to move toward the thermoplastic drill 103 at a preset moving speed, so that the thermoplastic drill 103 extrude and rotationally finish the softened plastic deformation area of ​​the workpiece 102, and finally process a hole of the required size and a high-quality bushing.

[0057] Similar to the control method described above, during the actual machining process, the decision as to whether to move the thermoplastic drill 103 toward the workpiece 102 or the machine table 101 toward the thermoplastic drill 103 can be made based on the specific circumstances. For example, if the workpiece 102 is of high material density and large in size, and the weight makes it difficult to control the movement of the machine table 101, then the thermoplastic drill 103 can be controlled to form holes in the workpiece 102. Alternatively, different control methods can be selected based on different hole requirements. For example, if a large number of holes need to be formed, requiring multiple thermoplastic drills 103 and controlling multiple thermoplastic drills simultaneously is difficult, then the machine table 101 can be controlled to move the workpiece 102 toward the thermoplastic drill 103, thereby coordinating the hole formation with the thermoplastic drill 103. This application is not limited to specific solutions.

[0058] In this application, the preset movement speed can range from 10 mm / min to 2000 mm / min. The diameter of the thermoplastic drill can range from 0.1 mm to 20 mm. The diameter of the thermoplastic drill 103 refers to the diameter of the structure of the thermoplastic drill 103 that matches the hole diameter. Typically, the thermoplastic drill 103 has at least two drilling structures from bottom to top, with the upper drilling structure matching the hole diameter. Different values ​​can be selected depending on the diameter of the thermoplastic drill and / or the workpiece. The preset movement speed is positively correlated with the preset rotational speed and the preset amplitude, respectively.

[0059] Generally speaking, at the same speed, the higher the rotational speed, the greater the friction frequency between the thermoplastic drill and the workpiece during the same period of time, generating heat from friction and causing higher temperatures. At the same rotational speed, the faster the movement speed, the shorter the time the thermoplastic drill remains in contact with the same position on the workpiece, causing the temperature to rise more slowly and thus lowering the temperature. With the addition of ultrasonic vibration, the greater the amplitude of the ultrasonic vibration, similar to the higher rotational speed, the greater the friction frequency between the thermoplastic drill and the workpiece during the same period of time, generating heat from friction. This increases the amount of heat generated, allowing for faster movement speeds (for example, a rotational speed of 6000 rpm and a movement speed of 1500 mm / min) while maintaining the same rotational speed. This allows for sufficient temperature to reach soft plastic deformation in the workpiece. If the movement speed is not increased, the workpiece will melt, resulting in poor quality. Therefore, increasing the movement speed is necessary, thereby improving overall processing efficiency.

[0060] In ordinary drilling processing, if higher-quality hole walls and bushings need to be drilled, a higher rotation speed is required to match a higher moving speed to reach the corresponding softening temperature of the workpiece before processing can be carried out (for example, the rotation speed is 6000 rpm and the moving speed is 500 mm / min); however, ultrasonic vibration has high-frequency vibration, and the drilling process will generate a higher temperature than ordinary drilling. Therefore, at the same rotation speed, a higher moving speed can be used to make the workpiece reach the corresponding softening temperature and obtain high-quality hole walls and bushings (for example, the rotation speed is 6000 rpm and the moving speed is 1000 mm / min). Compared with traditional processing, the moving speed is increased, thereby improving processing efficiency.

[0061] During the processing, the linear speed V C The relationship between the diameter D of the thermoplastic drill and the rotation speed N satisfies: F is a constant. Linear velocity V C Directly related to the thermoplastic drilling force, more specifically, the linear velocity V C It is inversely proportional to the machining force. According to the above formula, under the same tool diameter D, the larger the speed N, the greater the linear speed V. C The larger the rotation speed N is, the smaller the processing force will be, which will not easily cause the thermoplastic drill to break and obtain high-quality holes. At the same time, as the rotation speed N increases, the temperature generated will increase. Therefore, it is necessary to adjust the rotation speed (reduce the rotation speed) or increase the moving speed according to the actual situation, so that only the thermoplastic state temperature of the material is reached during the hole forming process. The above is for ordinary hole forming. For ultrasonic-assisted hole forming, the same rotation speed can be maintained, and the moving speed can be further increased to obtain higher-quality holes. According to current research, the diameter range of the thermoplastic drill is matched with the rotation speed, moving speed and vibration frequency (i.e., amplitude). Different rotation speeds, moving speeds and amplitudes are matched according to different thermoplastic drill diameters to obtain a processing force suitable for thermoplastic drill processing, which can process high-quality holes while also protecting the thermoplastic drill.

[0062] The above describes the method of forming a desired hole by controlling the relative rotation, ultrasonic vibration, and movement of a thermoplastic drill 103 and a workpiece 102. Although processing parameters such as rotation speed, vibration amplitude, and movement speed have different numerical ranges, in actual applications, once the workpiece 102 and thermoplastic drill 103 are identified, a set of processing parameters can typically be directly determined. The workpiece 102 can then be processed directly using these parameters, which is convenient and quick.

[0063] In other embodiments, in order to improve the accuracy of hole formation, the processing parameters can also be adjusted during the processing so that the processing parameters at different processing stages are different. Specifically, the thermoplastic drill 103 includes at least two processing parts. During the processing, when the workpiece is processed at different processing parts, at least one of the preset rotation speed, the preset amplitude and the preset movement speed is adjusted. In this way, holes of different sizes can be formed at different positions. It is understandable that the processing parameters can also be adjusted according to different processing procedures. For example, when the thermoplastic drill 103 and the workpiece 102 just come into contact, one set of processing parameters is selected, and after a preset time, another set of processing parameters is adjusted. This application does not limit the specific adjustment scheme of the processing parameters.

[0064] In summary, the present application adds an ultrasonic vibration process on the basis of the traditional hot melt drilling process, so that the hole forming method of the present application can adapt to the hole processing of different materials, especially materials with high hardness, wear resistance and high temperature resistance, such as workpieces formed by titanium alloy materials. The working process of processing titanium alloy workpieces using the high-frequency ultrasonic vibration plus high-speed rotation process of the present application is as follows: first, the tool handle 105 is connected to the vibration control device 104 to form an ultrasonic vibration system, so that the thermoplastic drill 103 forms high-frequency up and down vibrations, and the main shaft drives the thermoplastic drill 103 to rotate at high speed while driving the thermoplastic drill 103 to feed axially. When the thermoplastic drill 103 contacts the titanium alloy workpiece, due to the high-speed rotation of the main shaft and the high-frequency vibration of the thermoplastic drill 103, the contact part of the thermoplastic drill 103 and the workpiece 102 generates a large amount of heat, quickly heats up, and reaches a softened plastic deformation state. As the thermoplastic drill 103 moves downward (feeds), the workpiece 102 extrude and rotationally finish the softened plastic deformation area of ​​the workpiece, and finally processes a hole of the required size and a high-quality bushing.

[0065] Based on the ultrasonic-assisted thermoplastic drilling principle described above, this application takes the machining of a 1.8 mm diameter hole in TC4 titanium alloy as an example, and presents nine different embodiments based on the inconsistency of machining parameters:

[0066] Example 1: rotation speed 6000 rpm, feed speed (i.e., moving speed) 1000 mm / min, ultrasonic power: 80%;

[0067] Example 2: rotation speed 2000-5000 rpm, feed speed 500 mm / min, ultrasonic power: 80%;

[0068] Example 3: Rotational speed 500-1000 rpm, feed speed 100 mm / min, ultrasonic power: 80%.

[0069] Example 4: rotation speed 2000-5000 rpm, feed speed 500 mm / min, ultrasonic power: 0%;

[0070] Example 5: rotation speed 2000-5000 rpm, feed speed 1000 mm / min, ultrasonic power: 80%;

[0071] Example 6: rotation speed 2000-5000 rpm, feed speed 1500 mm / min, ultrasonic power: 100%;

[0072] Example 7: rotation speed 6000 rpm, feed speed 1000 mm / min, ultrasonic power: 50%;

[0073] Example 8: rotation speed 6000 rpm, feed speed 1500 mm / min, ultrasonic power: 80%;

[0074] Example 9: rotation speed 6000 rpm, feed speed 800 mm / min, ultrasonic power: 30%.

[0075] In Example 1, the rotation speed of thermoplastic drill 103 was 6000 rpm, the feed rate was 1000 mm / min, and the ultrasonic power was 80%. Because the rotation speed of thermoplastic drill 103 was too high, the temperature generated by frictional heat increased, causing the TC4 titanium alloy workpiece to reach its melting point, forming a molten state. At higher feed rates, the molten TC4 titanium alloy workpiece, under the impact of the feed, could form a longer bushing. However, when the molten metal cooled, the uneven cooling caused by the varying thickness resulted in an incomplete bushing. Furthermore, the high temperature caused more titanium chips to adhere to the hole wall, resulting in a poorly finished hole. Therefore, ultrasonic-assisted titanium alloy thermoplastic drilling is not suitable for high-speed, high-feed drilling.

[0076] In Example 2, the thermoplastic drill 103 rotates at a speed of 2000-5000 rpm, a feed rate of 500 mm / min, and an ultrasonic power of 80%. Under these processing parameters, the rotational speed is appropriate, and the frictional heat generated is just enough to achieve a soft plastic state in the TC4 titanium alloy processing area. The feed rate, under the influence of which, produces a punching effect on the soft plastic titanium alloy. Furthermore, the ultrasonic vibration improves the rigidity of the drilling system, ultimately resulting in a connection hole with excellent wall quality, uniform bushing thickness, and integrity. Furthermore, there is no titanium shavings adhering to the hole wall surface. Consequently, under these processing conditions, the thermoplastic drill experiences minimal wear.

[0077] In Example 3, the rotation speed of the thermoplastic drill 103 is 500-1000 rpm, the feed speed is 100 mm / min, and the ultrasonic power is 80%. Under these processing parameters, the rotation speed is relatively low, and the soft plastic state achieved by the TC4 titanium alloy workpiece area is not as soft as in Example 2. It is a relatively hard material. Therefore, under the punching pressure of the feed, a large impact force will be generated, resulting in unstable processing and ultimately uneven thickness of the bushing. One side is thick and the other side is thin, and the hole wall quality is worse than that of Example 2, but equivalent to that of Example 1. Therefore, the ultrasonic-assisted titanium alloy thermoplastic drilling process is not suitable for drilling at a lower rotation speed.

[0078] In Example 4, the rotation speed of the thermoplastic drill 103 is 2000-5000 rpm, the feed speed is 500 mm / min, and the ultrasonic power is 0%. Under these processing parameters, due to the lack of ultrasonic vibration, the temperature generated by the frictional heat generated by the rotation speed makes the soft plastic state achieved in the TC4 titanium alloy workpiece area not as soft as in Example 2, and it is a relatively hard material. Therefore, under the punching pressure of the feed, a large impact force is generated, resulting in unstable processing and ultimately uneven thickness of the bushing. One side is thick and the other side is thin, and the hole wall quality is poorer than that of Example 2. Therefore, the processing process of titanium alloy thermoplastic drilling without ultrasonic assistance is not suitable for drilling at lower rotation speeds.

[0079] In Example 5, the rotation speed of the thermoplastic drill 103 was 2000-5000 rpm, the feed rate was 1000 mm / min, and the ultrasonic power was 80%. Under these processing parameters, due to the assistance of ultrasonic vibration, compared to Example 4, the temperature generated by the rotation speed and ultrasonic frictional heat caused the TC4 titanium alloy workpiece area to reach a soft plastic state. At the higher feed rate, the soft plastic titanium alloy was punched, improving processing efficiency. Moreover, under the premise that the ultrasonic vibration increased the rigidity of the drilling system, the final connection hole with excellent hole wall quality and uniform and complete bushing thickness was formed.

[0080] In Example 6, the rotational speed of the thermoplastic drill 103 was 2000-5000 rpm, the feed rate was 1500 mm / min, and the ultrasonic power was 100%. Under these processing parameters, the ultrasonic vibration assisted the rotational speed and the temperature generated by ultrasonic friction, causing the TC4 titanium alloy workpiece area to reach a soft plastic state. Compared to Example 2, the higher feed rate allowed for faster punching of the soft plastic titanium alloy, improving processing efficiency. Furthermore, given the ultrasonic vibration's enhanced rigidity in the drilling system, the resulting connection hole had excellent wall quality and a uniform and complete bushing thickness.

[0081] In Example 7, the rotation speed of the thermoplastic drill 103 was 6000 rpm, the feed rate was 1000 mm / min, and the ultrasonic power was 50%. Under these processing parameters, the high rotation speed of the thermoplastic drill 103 resulted in higher temperatures due to frictional heat generation. However, compared to Example 1, the ultrasonic vibration power was lower. As a result, the TC4 titanium alloy workpiece reached a lower melting temperature, forming a critical molten state. At higher feed rates, the critical molten state of the TC4 titanium alloy workpiece could be subjected to the impact of the feed, resulting in a longer bushing. After the molten metal cooled, the bushing thickness was more uniform compared to Example 1. Furthermore, since the temperature did not reach the melting point, less titanium chips adhered to the hole wall, resulting in a smoother hole wall. Therefore, at the same rotation speed, lower ultrasonic power can produce higher-quality holes.

[0082] In Example 8, the rotation speed of the thermoplastic drill 103 was 6000 rpm, the feed rate was 1500 mm / min, and the ultrasonic power was 80%. Under these processing parameters, due to the ultrasonic vibration assistance, the rotation speed of the thermoplastic drill 103 was too high, resulting in higher temperatures due to frictional heat generation. However, compared to Example 1, the feed rate was higher, so the TC4 titanium alloy workpiece reached a lower melting temperature, forming a critical molten state. At the higher feed rate, the critical molten state of the TC4 titanium alloy workpiece could be subjected to the impact of the feed, forming a longer bushing. After the molten metal cooled, the bushing thickness was more uniform compared to Example 1. Furthermore, because the temperature did not reach the melting point, less titanium chips adhered to the hole wall, resulting in a smoother hole wall. Therefore, at the same rotation speed and ultrasonic power, ultrasonic processing with a higher feed rate can produce higher-quality holes.

[0083] In Example 9, the rotation speed of the thermoplastic drill 103 was 6000 rpm, the feed rate was 800 mm / min, and the ultrasonic power was 30%. Under these processing parameters, the high rotation speed of the thermoplastic drill 103 resulted in higher temperatures due to frictional heat generation. However, compared to Example 1, the ultrasonic vibration power was lower, resulting in a lower temperature for the TC4 titanium alloy workpiece. Even at a relatively low feed rate, the temperature rise of the TC4 titanium alloy workpiece was relatively slow, keeping the TC4 in a soft plastic state. Therefore, stable processing was possible at relatively low feed rates, resulting in a uniform bushing thickness, less titanium chips adhering to the hole wall, and a smoother hole wall. In other words, at the same rotation speed, lower ultrasonic power can be combined with a lower feed rate to produce higher-quality holes.

[0084] From the above nine embodiments, it can be seen that when processing titanium alloy workpieces, the processing parameters of embodiments 2, 5, 6, 7, 8 and 9 are more suitable and the hole forming effect is better.

[0085] In summary, the present invention utilizes an ultrasonically assisted thermoplastic drilling system, wherein a thermoplastic drill and / or a machine tool rotate at a preset speed and ultrasonically vibrate at a preset amplitude, thereby controlling the thermoplastic drill to move toward a workpiece or controlling the machine tool table to move toward the thermoplastic drill to drill the workpiece and form a desired hole. This system addresses the problems of excessive cutting forces, drill adhesion, and drill wear associated with conventional flow drills when machining hard, wear-resistant, and high-temperature resistant materials, such as titanium alloys. By ultrasonically vibrating the thermoplastic drill, the present invention effectively reduces cutting forces during drilling, thereby reducing drill wear and tear. Furthermore, since the thermoplastic drill is constantly in a high-frequency ultrasonic vibration state, it facilitates chip removal within the hole, preventing adhesion between the drill and the workpiece substrate, thereby preventing breakage. Furthermore, because ultrasonic vibration increases the rigidity of the drilling system, the machining process becomes more stable, resulting in high-quality hole walls and bushings when drilling difficult-to-machine materials, such as titanium alloys. Thanks to the high-frequency vibration of the thermoplastic drill after loading ultrasound, the adhesion of the thermoplastic drill to the workpiece substrate can be avoided. When ultrasonic-assisted thermoplastic drilling is used, it is not necessary to reach the melting temperature of the workpiece, such as titanium alloy. The hot drilling process can be carried out only when the temperature reaches its softening and plastic deformation temperature, which greatly reduces the processing temperature and is beneficial to extending the life of the thermoplastic drill.

[0086] Obviously, the embodiments described above are only some of the embodiments of the present application, rather than all of the embodiments. The preferred embodiments of the present application are given in the accompanying drawings, but they do not limit the patent scope of the present application. The present application can be implemented in many different forms. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present application more thorough and comprehensive. Although the present application has been described in detail with reference to the aforementioned embodiments, for those skilled in the art, it is still possible to modify the technical solutions described in the aforementioned specific embodiments, or to make equivalent replacements for some of the technical features therein. Any equivalent structure made using the contents of the present application specification and the accompanying drawings, directly or indirectly used in other related technical fields, is also within the scope of patent protection of the present application.

Claims

1. A drilling method based on ultrasonic assisted thermoplasticity, characterized in that: The drilling method is applied to a drilling system based on ultrasonic assisted thermoplasticity, and the method comprises: Controlling the drilling system to rotate at a preset speed and to perform ultrasonic vibration at a preset amplitude; The drilling system is controlled to move toward a workpiece, so that the workpiece reaches a softening plastic temperature so as to drill a hole in the workpiece, and a bushing is formed on an edge of the hole.

2. The method according to claim 1, characterized in that The drilling system includes a machine tool table carrying the workpiece and a thermoplastic drill; The step of controlling the drilling system to rotate at a preset speed and to perform ultrasonic vibration at a preset amplitude further includes: The machine tool worktable and / or the thermoplastic drill are controlled to rotate at the preset speed, and the machine tool worktable and / or the thermoplastic drill are controlled to perform ultrasonic vibration at the preset amplitude.

3. The method according to claim 2, characterized in that The step of controlling the machine tool worktable and / or the thermoplastic drill to perform ultrasonic vibration at the preset amplitude further includes: The machine tool table and / or the thermoplastic drill are controlled to perform the ultrasonic vibration at the preset amplitude in a preset direction relative to the workpiece, wherein the preset direction includes at least one group of the following directions: an up-down direction, a left-right direction, and a front-back direction relative to the workpiece.

4. The method according to claim 1, wherein The drilling system includes a machine tool table carrying the workpiece and a thermoplastic drill; The step of controlling the drilling system to move toward the workpiece includes: The thermoplastic drill is controlled to move toward the workpiece at a preset moving speed, or the machine tool worktable is controlled to move toward the thermoplastic drill at the preset moving speed, so as to drill a hole in the workpiece.

5. The method according to claim 4, characterized in that The preset rotation speed range is 100 rpm-10,000 rpm, the preset amplitude range is 0.1 μm-20 μm, and the preset moving speed range is 10 mm / min-2,000 mm / min.

6. The method according to claim 5, characterized in that The diameter of the thermoplastic drill is 0.1 mm to 20 mm, wherein the diameter of the thermoplastic drill refers to the diameter of the structure of the thermoplastic drill adapted to the hole diameter.

7. The method according to claim 6, characterized in that The preset rotation speed, the preset amplitude and the preset moving speed are selected to different values ​​according to the diameter of the thermoplastic drill and / or the workpiece; The preset moving speed is positively correlated with the preset rotation speed and the preset amplitude respectively.

8. The method according to claim 5, characterized in that The thermoplastic drill includes at least two processing parts; The method further comprises: When the workpiece is processed at different processing locations, at least one of the preset rotation speed, the preset amplitude, and the preset moving speed is adjusted.

9. A drilling system based on ultrasound-assisted thermoplasticity, characterized in that: The drilling system includes a machine tool table, a thermoplastic drill, a tool holder, a vibration control device, a rotation control device, and a movement control device, wherein: The machine tool worktable is used to carry the workpiece; The thermoplastic drill is connected to the tool handle, and the tool handle is further connected to the vibration control device, and is used to perform ultrasonic vibration with a preset amplitude under the control of the vibration control device, and drive the thermoplastic drill to perform ultrasonic vibration with the preset amplitude; The machine tool worktable and / or tool handle are further connected to the rotation control device and the movement control device, and the rotation control device and the movement control device are used to respectively control the machine tool worktable and / or the tool handle to rotate and move at a preset speed, so as to control the relative rotation and movement of the machine tool worktable and the thermoplastic drill to plasticize and drill the workpiece, and a bushing is formed on the edge of the hole.

10. The drilling system according to claim 9, characterized in that The diameter of the thermoplastic drill is 0.1 mm to 20 mm, wherein the diameter of the thermoplastic drill refers to the diameter of the structure of the thermoplastic drill adapted to the hole diameter.

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