阅读说明：本技术 超声辊抛光系统和方法以及用于机加工部件的方法 (Ultrasonic roller polishing system and method for machining a part ) 是由 高清 武颖娜 托马斯·爱德华·维克特 鲍莹斌 于 2017-04-21 设计创作，主要内容包括：一种超声辊抛光系统包括辊和控制器。该辊被配置成抵靠工件的表面被按压至按压深度,以进给速率在表面上滚压,并且在背压下以超声频率振动。该辊由驱动马达所驱动的运动单元按压并滚压。辊的振动由具有输入到其中的输入电流的超声振动单元驱动。控制器被配置成基于驱动马达的预期残余压缩应力和实时输出功率来调节按压深度、背压、输入电流和进给速率中的至少一者,以在工件中产生残余压缩应力,该残余压缩应力在基于预期残余压缩应力而预先确定的预期范围内。(An ultrasonic roller polishing system includes a roller and a controller. The roller is configured to be pressed against a surface of a workpiece to a pressing depth, roll on the surface at a feed rate, and vibrate at an ultrasonic frequency under back pressure. The roller is pressed and rolled by a moving unit driven by a driving motor. The vibration of the roller is driven by an ultrasonic vibration unit having an input current inputted thereto. The controller is configured to adjust at least one of the press depth, the back pressure, the input current, and the feed rate based on a desired residual compressive stress of the drive motor and the real-time output power to produce a residual compressive stress in the workpiece that is within a desired range that is predetermined based on the desired residual compressive stress.)

1. An ultrasonic roller polishing system comprising:

a roller configured to be pressed against a surface of a workpiece to a pressing depth, rolled on the surface at a feed rate, and vibrated at an ultrasonic frequency under a back pressure, wherein the roller is pressed and rolled by a moving unit driven by a drive motor, and the vibration of the roller is driven by an ultrasonic vibration unit having an input current input thereto;

a controller configured to adjust at least one of the press depth, the back pressure, the input current, and the feed rate based on an expected residual compressive stress and a real-time output power of the drive motor to produce a residual compressive stress in the workpiece that is within an expected range that is predetermined based on the expected residual compressive stress.

2. The system of claim 1, wherein the controller is configured to calculate at least one of an expected compression depth, an expected backpressure, an expected input current, and an expected feed rate based on the expected residual compressive stress and the real-time output power, and adjust at least one of the compression depth, the backpressure, the input current, and the feed rate as a function of the at least one of the expected compression depth, the expected backpressure, the expected input current, and the expected feed rate.

3. The system of claim 2, wherein the controller comprises:

a first calculator configured to calculate an expected output power based on the expected residual compressive stress; and

a second calculator configured to calculate at least one of the expected compression depth, the expected backpressure, the expected input current, and the expected feed rate based on the expected output power and the real-time output power.

4. An ultrasonic roller polishing method comprising:

pressing a roller against a surface of a workpiece to a pressing depth, and driving the roller to roll on the surface at a feed rate by a motion unit driven by a drive motor;

vibrating the roller at an ultrasonic frequency under back pressure, wherein the vibration of the roller is driven by an ultrasonic vibration unit having an input current input thereto; and

adjusting at least one of the press depth, the back pressure, the input current, and the feed rate based on an expected residual compressive stress and a real-time output power of the drive motor to produce a residual compressive stress in the workpiece that is within an expected range that is predetermined based on the expected residual compressive stress.

5. The method of claim 4, wherein the adjusting comprises:

calculating at least one of an expected compression depth, an expected back pressure, an expected input current, and an expected feed rate based on the expected residual compressive stress and the real-time output power; and

adjusting at least one of the compression depth, the backpressure, the input current, and the feed rate as a function of at least one of the desired compression depth, the desired backpressure, the desired input current, and the desired feed rate.

6. The method of claim 5, wherein the calculating comprises:

calculating an expected output power based on the expected residual compressive stress; and

calculating at least one of the expected compression depth, the expected backpressure, the expected input current, and the expected feed rate based on the expected output power and the real-time output power.

7. The method of claim 4, wherein the adjusting comprises: adjusting at least one of the compression depth, the backpressure, the input current, and the feed rate based on the expected residual compressive stress, the real-time output power, and at least one of a real-time compression depth, a real-time backpressure, a real-time input current, and a real-time feed rate.

8. The method of claim 7, wherein the adjusting comprises:

calculating an expected compression depth, an expected back pressure, and an expected feed rate based on the expected residual compressive stress, the real-time output power, and the real-time input current; and

adjusting the compression depth, the back pressure and the feed rate in accordance with the desired compression depth, the desired back pressure and the desired feed rate.

9. A method for machining a component, comprising:

determining an expected distribution of residual compressive stress of the component, the expected distribution comprising location information of at least one expected region on the component and an expected residual compressive stress corresponding to the expected region; and

machining the desired region with an ultrasonic roller burnishing apparatus comprising a roller to produce a residual compressive stress in the desired region within a predetermined desired range based on the corresponding desired residual compressive stress, comprising:

pressing the roller against the surface of the intended area to a pressing depth, and driving the roller to roll on the surface at a feed rate by a motion unit driven by a drive motor,

vibrating the roller at an ultrasonic frequency under back pressure, wherein the vibration of the roller is driven by an ultrasonic vibration unit having an input current input thereto, an

Adjusting at least one of the compression depth, the back pressure, the input current, and the feed rate based on the expected residual compressive stress and real-time output power of the drive motor.

10. The method of claim 9, wherein the expected distribution comprises location information for a first expected region and a first expected residual compressive stress corresponding to the first expected region, and location information for a second expected region and a second expected residual compressive stress corresponding to the second expected region; and the generating of the residual compressive stress comprises:

machining the first intended region of the component to produce a first residual compressive stress in the first intended region, the first residual compressive stress being within a first intended range that is predetermined based on the first intended residual compressive stress; and

machining the second intended region of the component to produce a second residual compressive stress in the second intended region, the second residual compressive stress being within a second intended range that is predetermined based on the second intended residual compressive stress.

Background

Embodiments of the present disclosure relate generally to ultrasonic roller polishing systems and methods, and more particularly to methods for machining components.

Residual compressive stress refers to the compressive stress remaining in the solid material after the initial stress cause is removed. The residual compressive stress effectively extends the fatigue life of the component, relieves corrosion fatigue and reduces stress corrosion cracking.

In conventional methods, residual compressive stresses may be introduced into the component by ultrasonic roll polishing methods. In some cases, residual compressive stresses having different values are required for different regions of the component, respectively. However, the conventional ultrasonic roll polishing method cannot control the value of the introduced residual compressive stress, and thus cannot well satisfy the performance requirements of the component.

Accordingly, it is desirable to provide a novel ultrasonic roll polishing system and method for machining components to address the above-mentioned problems, as well as a novel method.

Disclosure of Invention

In one aspect, an ultrasonic roller polishing system includes a roller and a controller. The roller is configured to be pressed against a surface of a workpiece to a pressing depth, rolled on the surface at a feed rate, and vibrated at an ultrasonic frequency under a back pressure, wherein the roller is pressed and rolled by a moving unit driven by a drive motor, and the vibration of the roller is driven by an ultrasonic vibration unit having an input current input thereto. The controller is configured to adjust at least one of the press depth, the back pressure, the input current, and the feed rate based on a desired residual compressive stress of the drive motor and the real-time output power to produce a residual compressive stress in the workpiece that is within a desired range that is predetermined based on the desired residual compressive stress.

In another aspect, an ultrasonic roller polishing method includes: pressing the roller against the surface of the workpiece to a pressing depth; and a motion unit drive roller driven by the drive motor rolls over the surface at a feed rate; vibrating the roller at an ultrasonic frequency under back pressure, wherein the vibration of the roller is driven by an ultrasonic vibration unit having an input current inputted thereto; and adjusting at least one of the press depth, the back pressure, the input current, and the feed rate based on the desired residual compressive stress and the real-time output power of the drive motor to produce a residual compressive stress in the workpiece that is within a desired range that is predetermined based on the desired residual compressive stress.

In another aspect, a method for machining a component includes determining an expected distribution of residual compressive stress for the component, where the expected distribution includes location information for at least one expected region on the component and an expected residual compressive stress corresponding to the expected region. The method also includes machining the desired region with an ultrasonic roller burnishing apparatus including a roller to produce a residual compressive stress in the desired region that is within a predetermined desired range based on a corresponding desired residual compressive stress. The machining step includes pressing the roller against the surface of the desired area to a pressing depth, and driving the roller at a feed rate by a movement unit driven by a drive motor; vibrating the roller at an ultrasonic frequency under back pressure, wherein the vibration of the roller is driven by an ultrasonic vibration unit having an input current inputted thereto; and adjusting at least one of the compression depth, the backpressure, the input current, and the feed rate based on the expected residual compressive stress and the real-time output power of the drive motor.

Drawings

These and other features, aspects, and advantages of the present disclosure will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:

FIG. 1 is a sketch of an ultrasonic roller burnishing system according to an exemplary embodiment of the present disclosure, wherein the ultrasonic roller burnishing system comprises a controller;

FIG. 2 is a sketch of the controller of FIG. 1 according to an exemplary embodiment of the present disclosure;

FIG. 3 is a flow chart illustrating an ultrasonic roller polishing method according to an exemplary embodiment of the present disclosure;

FIG. 4 is a flow chart illustrating an ultrasonic roller polishing method according to another exemplary embodiment of the present disclosure;

FIG. 5 is a flow chart illustrating a method for machining a component according to an exemplary embodiment of the present disclosure; and is

Fig. 6 is a sketch illustrating the residual compressive stress distribution of a component according to an exemplary embodiment of the present disclosure.

Detailed Description

In an effort to provide a concise description of these embodiments, not all features of an actual implementation are described in one or more specific embodiments. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.

Unless defined otherwise, technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. As used herein, the terms "first," "second," "third," "fourth," and the like, do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. Furthermore, the terms "a" and "an" do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item. The term "or" is intended to be inclusive and mean any, several, or all of the listed items. The use of "including," "comprising," or "having" and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items.

Embodiments of the present disclosure relate to an ultrasonic roller burnishing system that may be widely applied to part manufacturing and machining. The system can introduce residual compressive stress in the surface layer of the component and control the value or vertical distribution of the residual compressive stress in order to optimize the performance of the component.

Fig. 1 shows a sketch of an ultrasonic roller polishing system 10 according to an exemplary embodiment of the present disclosure. Referring to fig. 1, the ultrasonic roll polishing system 10 includes an ultrasonic roll polishing apparatus 20 configured to machine a workpiece 40, and a controller 30 configured to control the ultrasonic roll polishing apparatus 20 to machine the workpiece 40.

The ultrasonic roller burnishing device 20 includes a moving unit, a housing 29, a back pressure device 23, an ultrasonic vibration unit 22, and a roller 26. The motion unit includes a drive motor 28 and a plurality of motion components 211, 212, 213 configured to drive the housing 29 to move relative to the workpiece 40. The ultrasonic vibration unit 22 includes an ultrasonic generator 221, an ultrasonic transducer 222, and an ultrasonic horn 223. The back pressure device 23, the ultrasonic transducer 222, the ultrasonic horn 223 are received in the housing 29. The roller 26 is rotatably coupled to the ultrasonic horn 223 and is partially received in the housing 29. The roller 26 may rotate about its own axis or center and may be in the shape of a sphere or cylinder, but is not limited to these shapes.

The ultrasonic vibration unit 22 is configured to receive an input current I and drive the roller 26 to vibrate at an ultrasonic frequency. The ultrasonic generator 221 is configured to receive an input current I and output an oscillating current at an ultrasonic frequency. Reference hereinafter to ultrasonic frequencies is to frequencies above 20 kilohertz, for example in the range of about 20 kilohertz to about 30 kilohertz. The ultrasonic transducer 222 is coupled with the ultrasonic generator 221 and is configured to convert the oscillating electrical current into mechanical vibrations at an ultrasonic frequency. The ultrasonic transducer 222 may comprise a magnetostrictive transducer, a piezoelectric ceramic transducer, or a combination thereof. An ultrasonic horn 223 is coupled to the ultrasonic transducer 222 and is configured to amplify the amplitude of the mechanical vibrations. The roller 26 is coupled with an ultrasonic horn 223 such that the ultrasonic horn 223 is configured to directly drive the roller 26 to vibrate at an ultrasonic frequency. The roller has a vibration intensity corresponding to the value of the input current I. In some embodiments, the roller has an amplitude of vibration that is less than 100 microns, such as in a range of about 10 microns to about 50 microns, or about 10 microns to about 12 microns. In some embodiments, the rollers oscillate in a direction perpendicular to the surface of the workpiece 40.

The back pressure device 23 is configured to exert a back pressure BP on the roller 26, and thus the roller transmits the pressure to the workpiece 40. The back pressure BP is also configured to increase the resistance to vibration of the roller 26, thereby improving the stability of the vibration. The back pressure device 23 may comprise a pneumatic device, a hydraulic device, a spring or a combination thereof. In some embodiments, the back pressure device 23 comprises a pneumatic device that generates a back pressure by compressing a gas therein. The back-pressure device 23 may also comprise a proportional valve for regulating the pressure of the gas and, therefore, the value of the back-pressure exerted on the roller 26.

The movement unit driven by the drive motor is configured to move the housing 29 and thus the roller 26 relative to the workpiece 40. For example, the moving unit is configured to move the roller 26 in a direction perpendicular to the surface of the workpiece. Thus, the motion unit is configured to press the roller 26 onto the surface of the workpiece to a press depth D, wherein the press depth D is adjustable according to commands or instructions from the controller 30. The motion unit is also configured to drive the roller 26 to roll over the surface of the workpiece 40 at a feed rate. Thus, the roller 26 may be pressed against the surface of the workpiece while it rolls over the surface at the feed rate.

When the ultrasonic roller polishing apparatus is operated, the roller is pressed against the surface while rolling and vibrating on the surface, so as to polish the surface of the workpiece and introduce residual compressive stress in the workpiece. The output power of the drive motor may be indicative of the introduced residual compressive stress, and is dependent on the compression depth D, the back pressure BP, the input current I and the feed rate f. Therefore, the output power of the drive motor and the residual compressive stress can be controlled by adjusting at least one of the pressing depth D, the back pressure BP, the input current I, and the feed rate f.

The controller 30 is configured to determine the expected residual compressive stress S based on the drive motor 28_eAnd real-time output power P_rAt least one of the pressing depth D, the back pressure, the input current I, and the feed rate f is adjusted to produce a residual compressive stress in the workpiece. The resulting residual compressive stress is based on the expected residual compressive stress S_eBut within a predetermined expected range. In some casesIn embodiments, the desired residual compressive stress refers to a value of the residual compressive stress at a certain depth, or an average value of the residual compressive stress over a certain depth range. The expected range refers to a range of values around the value or average of the residual compressive stress. Specifically, the controller 30 is configured to determine the expected residual compressive stress S based on the expected residual compressive stress_eAnd real-time output power P_rTo calculate the expected compression depth D_eExpected back pressure BP_eExpected input current I_eAnd a desired feed rate f_eAt least one of (a). Then, at least one of the compression depth D, the back pressure, the input current I, and the feed rate f is set according to the desired compression depth D_eExpected back pressure BP_eExpected input current I_eAnd a desired feed rate f_eAt least one of (a).

In some embodiments, the controller 30 is configured to determine the expected residual compressive stress S based on the expected residual compressive stress S_eAnd real-time output power P_rTo calculate the expected compression depth D_eExpected back pressure BP_eExpected input current I_eAnd a desired feed rate f_e. Then, the depth of compression D, the back pressure, the input current I and the feed rate f are determined according to the desired depth of compression D_eExpected back pressure BP_eExpected input current I_eAnd a desired feed rate f_eTo adjust.

Referring to fig. 2, the controller 30 includes a first controller 31 and a second controller 32. The first calculator 31 is configured to calculate the expected residual compressive stress S based on the expected residual compressive stress S_eTo calculate the expected output power P_e. The second calculator 32 is configured to calculate the desired output power P_eAnd real-time output power P_rTo calculate the expected compression depth D_eExpected back pressure BP_eExpected input current I_eAnd a desired feed rate f_eAt least one of (a).

Embodiments of the present disclosure also relate to ultrasonic roll polishing methods for machining workpieces. The method can effectively control the value or state of residual compressive stress induced in the workpiece by monitoring the output power of the drive motor in real time.

Fig. 3 is a flowchart illustrating an ultrasonic roll burnishing method 50 of machining a workpiece with an ultrasonic roll burnishing apparatus including a roll and a motion unit according to an exemplary embodiment of the present disclosure. Referring to fig. 3, method 50 includes steps 51 through 55. While the actions of method 50 are illustrated as functional blocks, the order of the blocks and the separation of actions among the various blocks illustrated in FIG. 3 are not intended to be limiting. For example, the blocks may be performed in a different order, and actions associated with one block may be combined with one or more other blocks, or may be subdivided into multiple blocks.

In step 51, the expected residual compressive stress of the workpiece is determined according to actual needs. The expected residual compressive stress refers to an expected state of residual compressive stress that is expected to be introduced, which may include a value of the residual compressive stress at a certain depth, a distribution of the residual compressive stress over a certain depth, an average of the residual compressive stress over a certain depth, or a combination thereof.

In step 52, the motion unit presses the roller of the ultrasonic roller burnishing device against the surface of the workpiece to a pressing depth, and drives the roller to roll over the surface at a feed rate. The motion unit is driven by a drive motor. In some embodiments, the motive unit drive roller rolls over the surface along a predetermined path.

In step 53, the roller is vibrated at an ultrasonic frequency under back pressure, wherein the vibration of the roller is driven by an ultrasonic vibration unit having an input current input thereto. The amplitude or intensity of the vibration can be adjusted by changing the frequency or amplitude of the input current. In some embodiments, the vibration of the roller is in a direction perpendicular to the surface. The back pressure exerted on the roller is generated by a back pressure device.

In step 54, the real-time output power of the drive motor is detected. The output power of the drive motor may be indicative of the residual compressive stress introduced, and thus the residual compressive stress may be controlled by controlling the output power of the drive motor. There is a relationship between the output power of the drive and the resulting residual compressive stress, where the relationship may be represented by one or more mathematical models.

In step 55, at least one of the pressing depth, the back pressure, the input current, and the feed rate is adjusted based on the expected residual compressive stress determined in step 51 and the real-time output power of the drive motor detected in step 54 to produce a residual compressive stress in the workpiece within an expected range predetermined based on the expected residual compressive stress.

In some embodiments, the method further comprises calculating an expected output power based on the expected residual compressive stress. The adjusting includes adjusting at least one of the compression depth, the backpressure, the input current, and the feed rate based on the desired output power and the real-time output power. In particular, when the expected output power is higher than the real-time output power, the adjusting includes increasing at least one of the compression depth, the backpressure, and the input current, and/or decreasing the feed rate. When the desired output power is lower than the real-time output power, the adjusting includes reducing at least one of the compression depth, the backpressure, and the input current, and/or increasing the feed rate.

In some embodiments, step 55 further comprises calculating at least one of an expected compression depth, an expected back pressure, an expected input current, and an expected feed rate based on the expected residual compressive stress and the real-time output power, and then adjusting at least one of the compression depth, the back pressure, the input current, and the feed rate according to the at least one of the expected compression depth, the expected back pressure, the expected input current, and the expected feed rate.

In some implementations, the calculation of at least one of the expected compression depth, the expected back pressure, the expected input current, and the expected feed rate includes calculating an expected output power based on the expected residual compressive stress; and calculating at least one of a desired compression depth, a desired back pressure, a desired input current, and a desired feed rate based on the desired output power and the real-time output power.

In some embodiments, all of the compression depth, backpressure, input current, and feed rate are adjusted based on the expected residual compressive stress and real-time output power of the drive motor. Thus, step 55 comprises calculating a desired compression depth, a desired back pressure, a desired input current and a desired feed rate, and then adjusting the compression depth, back pressure, input current and feed rate in accordance with the desired compression depth, desired back pressure, desired input current and desired feed rate. It is worth mentioning that multiple sets of desired compression depths, desired back pressures, desired input currents and desired feed rates may be obtained based on the desired residual compressive stress and the real-time output power. Their best group can be selected as the basis for adjustment according to actual needs.

In some embodiments, to improve response speed, only a fraction of the four parameters (i.e., compression depth, backpressure, input current, and feed rate) are selected for adjustment.

Fig. 4 is a flowchart illustrating an ultrasonic roller polishing method 60 according to another exemplary embodiment of the present disclosure.

Steps 61-64 are similar to steps 51-54, respectively, of method 50 shown in FIG. 3 and will not be repeated here.

In step 65, at least one of a real-time compression depth, a real-time back pressure, a real-time input current, and a real-time feed rate is detected. The detected real-time parameters will be used as the basis for adjustment of other parameters as well as the expected residual compressive stress and real-time output power.

In step 66, at least one of the compression depth, back pressure, input current and feed rate is adjusted based on the expected residual compressive stress, real-time output power and real-time parameters obtained in step 65.

For example, a real-time input current is detected in step 65. Then, in step 66, the compression depth, back pressure and feed rate are adjusted based on the desired residual compressive stress, the real-time output power and the real-time input current. Specifically, a desired compression depth, a desired back pressure and a desired feed rate are calculated based on the desired residual compressive stress, the real-time output power and the real-time input current, and then the compression depth, the back pressure and the feed rate are adjusted according to the desired compression depth, the desired back pressure and the desired feed rate.

Embodiments of the present disclosure also relate to methods for machining components that may be broadly applied in the manufacture of turbine or aircraft blades. The method includes determining an expected distribution of residual compressive stress of the component, wherein the expected distribution includes location information of at least one expected region on the component and an expected residual compressive stress corresponding to the expected region. The method also includes treating the desired region with an ultrasonic roll polishing device including a roll to produce a residual compressive stress in the desired region that is within a predetermined desired range based on a corresponding desired residual compressive stress such that a desired distribution of residual compressive stress can be introduced in the component.

Fig. 5 is a flowchart illustrating a method 70 for machining a component according to an exemplary embodiment of the present disclosure. Referring to fig. 5, method 70 includes steps 71 through 73.

In step 71, an expected distribution of residual compressive stress of the component is determined. As shown in FIG. 6, the expected distribution includes position information of a first expected area 81 on the part, a first expected residual compressive stress S corresponding to the first expected area 81₁Location information of a second expected region 82 on the component and a second expected residual compressive stress S corresponding to the second expected region 82₂。

In step 72, the first desired region 81 is machined to produce a first residual compressive stress in the first desired region that is based on the first desired residual compressive stress S₁But within a predetermined first expected range.

In step 73, the second desired region 82 is machined to produce a second residual compressive stress in the second desired region that is based on the second desired residual compressive stress S₂But within a predetermined second expected range.

Step 72 or 73 comprises pressing the roller against the surface of the desired area to a pressing depth; a kinematic unit driven roller driven by a drive motor rolls over the surface at a feed rate; vibrating the roller at an ultrasonic frequency under back pressure, wherein the vibration of the roller is driven by an input current; and adjusting at least one of the compression depth, the backpressure, the input current, and the feed rate based on the expected residual compressive stress and the real-time output power of the drive motor.

As will be understood by those skilled in the art, the present disclosure may be embodied in other specific forms without depending on the essential or essential characteristics thereof. Accordingly, the disclosure and description herein are intended to be illustrative, but not limiting, of the scope of the disclosure, which is set forth in the following claims.