Method and apparatus for impacting metal parts

A driven member of a metal peening machine is disclosed. The metal peening machine is configured to drive the driven member into contact with a work surface of a metal workpiece to deform the metal workpiece. The driven member includes a shaft with an impact end. At least one of a plurality of impact features, an impact feature with a non-flat impact surface, a non-round impact feature, and an asymmetrical impact feature is coupled to and protrudes from the impact end of the shaft. The at least one of the plurality of impact features, the impact feature with a non-flat impact surface, the non-round impact feature, and the asymmetrical impact feature defining at least one impact surface to be driven into contact with the work surface of the metal workpiece.

FIELD

The disclosure relates to the use of mechanical systems to change physical characteristics of metal parts. More specifically, the disclosure relates to a method and apparatus for mechanically processing, such as by impact peening, metal workpieces into final metal components for aircraft and aerospace applications.

BACKGROUND

Currently, metal parts are fabricated from sheet and plate product forms into, but not limited to, fuselage skins, wing skins, and other structures for aircraft by using systems including shot peening, ultrasonic peening, and laser peening. Shot peening works well on thinner material but is difficult to control, such as when precision processing of a part is required. For thicker materials, large shot peening is required to process the part. Large shot peening may damage the surface of the part to the point where additional processing steps may be required to meet surface finish requirements. Ultrasonic peening and laser peening are used on both thick and thin metal components, but such systems require a substantial amount of time to process the metal components into the desired final condition. Additionally, laser peening requires high investment levels for both initial capital and later recurring costs. A need exists for providing an easily adjustable mechanical system to process components varying from thin sheet metal to those greater than one inch thick, where precise finishing of such metal components may be achieved more economically than presently available.

Conventional machines for peening metal parts have a limited range of available impact energies and impact reciprocation rates. Such limitations of metal peening machines correspondingly limit the types, materials, and geometries of the parts formed by the machines.

SUMMARY

The subject matter of the present application has been developed in response to the present state of the art, and in particular, in response to shortcomings of conventional impact peening systems for forming metal parts. The subject matter of the present application provides embodiments of metal peening systems, apparatuses, and methods that overcome at least some of the above-discussed shortcomings of prior art techniques. For example, according to some embodiments, a metal peening system of the present application includes a driven member or impactor with at least one of a plurality of impact features, an asymmetrical impact feature, or a non-round impact feature. Such an impactor is useful to increase the effective operational range of metal peening machines thereby broadening the types, materials, and geometries of parts capable of being formed by the metal peening machines.

According to a first example, an apparatus for changing physical characteristics of a metal workpiece having a surface includes a support for the workpiece. The apparatus also includes a driven member for applying multiple impacts to a surface of the workpiece. Further, the apparatus includes a controller that has adjustable parameters operatively connected to the driven member to operate the driven member for applying multiple impacts against the surface of the workpiece within a range of the adjustable parameters for changing physical characteristics of the metal workpiece. The apparatus additionally includes a fixture for pre-loading the workpiece while the driven member applies impacts to the workpiece.

According to a second example, an apparatus for changing physical characteristics of a metal workpiece having a surface includes a support for the workpiece and a driven member for applying multiple impacts to a surface of the workpiece. The apparatus also includes a controller that has adjustable parameters operatively connected to the driven member to operate the driven member for applying multiple impacts against the surface of the workpiece within a range of the adjustable parameters for changing physical characteristics of the metal workpiece. The support for the workpiece has a surface and wherein the workpiece has a second surface which bears against the surface of the support. Additionally, the support for the workpiece includes at least one clamp bearing against the surface of the workpiece and the support further includes at least one additional clamp bearing against the second surface of the workpiece.

In one implementation of the second example, the support includes further clamps that bear against the second surface of the workpiece and directly oppose the clamps bearing against the surface of the workpiece.

According to a third example, an apparatus for changing physical characteristics of a metal workpiece having a surface includes a support for the workpiece and a driven member for applying multiple impacts to a surface of the workpiece. The apparatus also includes a controller that has adjustable parameters operatively connected to the driven member to operate the driven member for applying multiple impacts against the surface of the workpiece within a range of the adjustable parameters for changing physical characteristics of the metal workpiece. The support for the workpiece has a surface and wherein the workpiece has a second surface which bears against the surface of the support. The support further includes biased clamps for securing the workpiece on the support and for securing the workpiece against the surface of the support.

According to a fourth example, an apparatus for changing physical characteristics of a metal workpiece having a surface includes a support for the workpiece and a driven member for applying multiple impacts to a surface of the workpiece. The apparatus also includes a controller that has adjustable parameters operatively connected to the driven member to operate the driven member for applying multiple impacts against the surface of the workpiece within a range of the adjustable parameters for changing physical characteristics of the metal workpiece. The support for the workpiece has a surface and wherein the workpiece has a second surface which bears against the surface of the support. The support further includes an air bladder anvil bearing against the second surface of the workpiece, and the apparatus further includes a pair of spaced clamps bearing against the surface of the workpiece.

In one implementation of the fourth example, the air bladder anvil is a preformed and shaped air bladder anvil.

According to a fifth example, an apparatus for changing physical characteristics of a metal workpiece having a surface includes a support for the workpiece and a driven member for applying multiple impacts to a surface of the workpiece. The apparatus also includes a controller that has adjustable parameters operatively connected to the driven member to operate the driven member for applying multiple impacts against the surface of the workpiece within a range of the adjustable parameters for changing physical characteristics of the metal workpiece. Additionally, the apparatus includes a crank mechanism for driving the driven member. The crank mechanism has a continuous reciprocally moving ram. The ram creates energy transformed into impact energy by the driven member. The impact energy moves as a stress wave from the driven member into the surface of the workpiece.

According to a sixth example, a driven member of a metal peening machine is disclosed. The metal peening machine is configured to drive the driven member into contact with a work surface of a metal workpiece to deform the metal workpiece. The driven member includes a shaft with an impact end. At least one of a plurality of impact features, an impact feature with a non-flat impact surface, a non-round impact feature, and an asymmetrical impact feature is coupled to and protrudes from the impact end of the shaft. The at least one of the plurality of impact features, the impact feature with a non-flat impact surface, the non-round impact feature, and the asymmetrical impact feature defining at least one impact surface to be driven into contact with the work surface of the metal workpiece.

In some implementations of the sixth example, the plurality of impact features are coupled to and protrude from the impact end of the shaft. Each of the plurality of impact features defines an impact surface. In one implementation of the sixth example, the plurality of impact features are uniformly spaced about the impact end. In one implementation of the sixth example, the plurality of impact features are non-uniformly spaced about the impact end. According to some implementations of the sixth example, each of the plurality of impact features comprises a rounded bump protruding from the impact end of the shaft. In certain implementations if the sixth example, the plurality of impact features are arranged in a symmetrical pattern about the impact end. In some implementations of the sixth example, the plurality of impact features are arranged in an asymmetrical pattern about the impact end. The plurality of impact features collectively define a textured impact surface in an implementation of the sixth example. According to certain implementations of the sixth example, at least one of the impact features of the plurality of impact features defines an impact surface with a non-round peripheral shape. The non-round peripheral shape of the impact surface can be asymmetrical. At least one of the impact features with the non-round peripheral shape may include an elongate ridge. According to one implementation of the sixth example, at least one of the plurality of impact features protrudes from the impact end a first distance, and at least one of the plurality of impact features protrudes from the impact end a second distance, where the first distance is different than the second distance. In certain implementations of the sixth example, at least one of the impact features of the plurality of impact features defines an impact surface having a first peripheral shape, and at least one of the impact features of the plurality of impact features defines an impact surface having a second peripheral shape, where the first peripheral shape is different than the second peripheral shape.

According to some implementations of the sixth example, the non-round impact feature is coupled to and protrudes from the impact end of the shaft. The non-round impact feature defines an impact surface with a non-round peripheral shape. The non-round peripheral shape of the impact surface can have a length greater than a width. The non-round peripheral shape of the impact surface can have an elliptical shape. The non-round peripheral shape of the impact surface may have a rectangular shape or square shape. The non-round impact feature can include an elongate ridge.

In certain implementations of the sixth example, the asymmetrical impact feature is coupled to and protrudes from the impact end of the shaft. The asymmetrical impact feature defines an impact surface with an asymmetrical peripheral shape.

According to certain implementations of the sixth example, the asymmetrical impact feature is coupled to and protrudes from the impact end of the shaft. The asymmetrical impact feature being asymmetrical relative to a plane parallel to a driving direction of the driven member when driven by the metal peening machine.

In a seventh example, a metal peening machine for forming a metal workpiece includes a driven member for applying multiple impacts to a surface of the workpiece. The driven member includes at least one of a plurality of impact features, an impact feature with a non-flat impact surface, a non-round impact feature, and an asymmetrical impact feature. Each of the plurality of impact features, impact feature with a non-flat impact surface, non-round impact feature, and asymmetrical impact feature define at least one impact surface to be driven into contact with the surface of the metal workpiece. The metal peening machine also includes a device for driving the driven member. Additionally, the metal peening machine includes a controller that is operably coupled to the device to control impact characteristics of the driven member.

According to some implementations of the seventh example, the metal peening machine also includes a plurality of interchangeable driven members each separately drivable by the device. Each of the plurality of interchangeable driven members has a different configuration of the at least one of the plurality of impact features, impact feature with a non-flat impact surface, non-round impact feature, and asymmetrical impact feature.

In an eighth example, a method of deforming a metal workpiece includes repeatedly impacting a surface of the metal workpiece with a driven member. The driven member includes at least one of a plurality of impact features, an impact feature with a non-flat impact surface, a non-round impact feature, and an asymmetrical impact feature. Each of the plurality of impact features, impact feature with a non-flat impact surface, non-round impact feature, and asymmetrical impact feature define at least one impact surface to be driven into contact with the surface of the metal workpiece. The method also includes setting impact characteristics of the driven member responsive to a configuration of the at least one of the plurality of impact features, impact feature with a non-flat impact surface, non-round impact feature, and asymmetrical impact feature defining at least one impact surface to be driven into contact with the surface of the metal workpiece.

According to some implementations of the eighth example, the driven member includes the plurality of impact features. Setting impact characteristics of the driven member includes setting one of a relatively high impact energy, relatively high impact reciprocation rate of the driven member, relatively low feed rate, and relatively small step-over distance corresponding with a higher quantity of impact features, and setting one of a relatively low impact energy, relatively low impact reciprocation rate of the driven member, relatively high feed rate, and relatively large step-over distance corresponding with a lower quantity of impact features.

DETAILED DESCRIPTION

Referring to the drawings, examples of the disclosure may be described in the context of an aircraft manufacturing and service method100as shown inFIG. 14and an aircraft102as shown inFIG. 15. During pre-production, exemplary method100may include specification and design104of the aircraft102and material procurement106. During production, component and subassembly manufacturing108and system integration110of the aircraft102take place. Thereafter, the aircraft102may go through certification and delivery112in order to be placed in service114. While in service by a customer, the aircraft102is scheduled for routine maintenance and service116(which may also include modification, reconfiguration, refurbishment, and so on).

As shown inFIG. 15, the aircraft102produced by exemplary method100may include an airframe118with a plurality of systems120and an interior122. Examples of high-level systems120include one or more of a propulsion system124, an electrical system126, a hydraulic system128, and an environmental system130. Any number of other systems may be included. Although an aerospace example is shown, the principles of the disclosure may be applied to other industries, such as the automotive industry.

Apparatus and methods embodied herein may be employed during any one or more of the stages of the production and service method100. For example, components or subassemblies corresponding to production process108may be fabricated or manufactured in a manner similar to components or subassemblies produced while the aircraft102is in service. Also, one or more apparatus example, method example, or a combination thereof may be utilized during the production stages108and110, for example, by substantially expediting assembly of or reducing the cost of an aircraft102. Similarly, one or more of apparatus example, method example, or a combination thereof may be utilized while the aircraft102is in service, for example and without limitation, to maintenance and service116.

Referring toFIGS. 14 and 15, the description of the present disclosure to be hereinafter provided generally falls within the component and subassembly manufacturing sub-step108and also generally falls within the airframe118of the aircraft102.

As shown in the FIGS., the present disclosure is directed to an apparatus and method for changing physical characteristics of metal workpieces or parts by multiple impacts. The workpiece W may be sheet metal, a metal plate, an extrusion, or an assembly and may have a thickness range of 0.062 to 2.00 inches. Each workpiece W may have different dimensions in length, width, and thickness. Moreover, each workpiece W may have multiple surfaces, which receive multiple impacts. The metal itself may be any metal, such as aluminum, titanium, or metal alloys. In essence, the metal or metal alloy workpiece W may exist in a variety of geometries and configurations.

Referring toFIGS. 2 and 3, an apparatus200is provided for changing physical characteristics of a metal workpiece. The workpiece W is securely positioned upon a support202. Although the support202is shown in the accompanying drawings as being in a horizontal position, it is to be understood that the support202for the workpiece W may be in a substantially vertical position and virtually at any angle between the vertical and horizontal positions of the workpiece W. A driven member204is provided to transfer the energy generated from the rotary impact device shown inFIG. 1through multiple impacts to the surface206of the workpiece W. The driven member204may or may not have a hardness greater than that of the workpiece W. The driven member204may be made from a single material or a combination of materials in series. The multiple impacts from the driven member204change physical characteristics or effects of the workpiece W until a final useful component or part, such as for use on an aircraft, is achieved.

As disclosed, the workpiece W may have a variety of geometries, including length. Each support202has certain dimensions and is able to receive and process each workpiece W. For example, in some cases, a workpiece W may be impacted in its entirety on a given support202by the driven member204. In other cases, a lengthy workpiece W may be processed in consecutive sections of the same workpiece. The leading section of such a lengthy workpiece W may be processed while being secured on the support202. The leading section is moved forward while adjacent trailing sections of similar dimensions are impacted in a stepwise manner.

In all of the workpieces W being processed, each workpiece W is supported in a fixed position during impacting by the driven member204over the entire surface206which is the equivalent of the impact coverage area. As to be described hereinafter in detail, in some embodiments, the driven member204is controlled by a manipulator and an end effector for impacting the entire coverage area of an entire workpiece W or of each section of a lengthy workpiece W while being secured in position.

Referring toFIG. 3, the driven member204applies multiple impacts to the surface206of a workpiece W and creates impact energy that moves as a stress wave from the driven member204to the surface of the workpiece W. The stress wave is then transferred from the surface206into a depth of the workpiece W to create a residual compressive stress or an internal compressive layer that persists within the workpiece W. The relationship of the compressive layer to a co-developed compensatory tensile layer of the workpiece W acts to change the workpiece into a component having changed physical characteristics or effects such as a desired contour for a desired final component.

The following description of the apparatus200provides details of one type of device210for driving the driven member204and of multiple possible types of supports202for the workpiece W. These descriptions will be followed by a description of the method of operation of the apparatus200by reference to the flow diagram shown inFIG. 13.

Referring toFIG. 1, one example of a device, generally210, for applying multiple impacts by the driven member204on a workpiece W is shown. The illustrated example device210is electrically driven. Such a device210may also be driven hydraulically or pneumatically. It is to be understood that other types of devices may be utilized provided that any such other device is capable of generating and imparting an impact energy into and through the driven member204. The illustrated device210is a crank mechanism and includes a housing212. The housing212has a rotatable crank214that is connected to a shaft (not shown) connected to an electric drive motor (not shown). The crank214provides multiple beats per minute by the driven member204on the surface206of the workpiece W and initially provides a driving force for a piston216. The piston216is reciprocally mounted within the housing212and has an O-ring218bearing against the cylindrical interior wall of the housing212.

Spaced from the piston216is a ram220, which is reciprocally mounted within the housing and has an O-ring218thereon. The ram220cooperates with the piston216to form an air spring222therebetween. The air spring222drives the ram220which accelerates a beat-piece224. The air spring222drives the ram220against a beat-piece224when it is moving forward and retrieves the ram220when the piston216retracts. The beat-piece224includes a pair of O-rings218for sealing against the housing212. The beat-piece224transfers energy of the ram220to an end of the driven member204which applies multiple impacts against the workpiece W. The impacts provide energy for moving a stress wave through the driven member204to the surface206of the workpiece W.

As described above, and referring toFIG. 7, the device210is used to cause multiple impacts by the driven member204to be applied against the surface206of the workpiece W. The following is a discussion of multiple examples of supports202for the workpiece W during the impacting by the driven member204against the surface206of each workpiece W being processed, regardless of the length of the workpiece W. In some cases, the driven member204applies impacts across the entire coverage area of the workpiece W, which is secured in position by a support202during the entire time that impacts are being applied.

The following description discloses various types of anvils located on the opposite side of the impacts by the driven member204against the surface206of the workpiece W. Each support202to be described functions as an anvil that forcibly opposes the impact side of the workpiece W. When a workpiece W is resting on a flat surface of a support202and is processed on the flat surface, portions of the workpiece W begin to rise off the flat surface of the support202and a gap forms between the flat surface and the risen portions of the workpiece W. This creates an undesired loss of energy due to the workpiece W vibrating in free air.

In essence, the supports202for the workpiece W, to be described in the following examples, reduce such loss of energy. In each example, the support202secures the workpiece W during processing. Each support202further acts as an anvil on the opposite side of the workpiece W while the driven member204is applying multiple impacts to the surface206of the workpiece W. Further, clamps of various types cooperate with the supports202to secure the workpiece W in place during impacting by the driven member204. The clamps, to be described later, may be elongated and may protrude for the entire length of the support202during impacting by the driven member204. The clamps are positioned to secure each workpiece at a selected location. In each example of the support202that follows, the driven member204is being driven by a device, such as the device210, described above.

Referring toFIG. 7, the workpiece W is mounted on a flat plate230, which is the support202for the workpiece W. The impact energy from the driven member204moves as a stress wave to the surface206of the workpiece. Clamps232, which are elongated, secure the workpiece W against the flat plate230to thereby avoid the compressive forces from the impacting to raise portions of the workpiece W and create a loss of energy.

Referring toFIG. 8, the support202comprises a pair of opposed clamps234, which are elongated and secure the workpiece W to avoid the raising of the workpiece W during impacting. At least one central clamp236, which is elongated, is mounted on the opposite side of the workpiece W and acts as an anvil in opposition to the impacts from the driven member204against the surface206of the workpiece W. The central clamp236can also be used to impart a pre-stress to the workpiece W by displacing the central clamp into the workpiece W. A stress wave moves through the driven member204to the surface206of the workpiece W. A portion of the resulting energy may be transferred into space on the opposite side of the surface of the workpiece W. A pair of optional clamps238may be placed on a side of the surface206opposite to the clamps234. The clamps234and the clamps236,238secure the workpiece W while reducing the loss of energy by the workpiece W during the impacting of the workpiece W by the driven member204.

FIG. 9is another alternative example of supporting a workpiece W. InFIG. 9, a plate240is provided with a raised anvil portion242which acts in opposition to the driven member204impacting the upper surface206of the workpiece W. In this example, a pair of biased clamps244, which are elongated, are provided to secure the workpiece W. Springs246bias the clamps244to secure the workpiece W against the raised anvil portion242. In some implementations, the springs246may apply a sufficient force against the workpiece W to pre-stress the workpiece W as the workpiece W conforms to the shape of the plate240. The springs246are positioned around a post248threaded into a plate240. The springs246are mounted between a head250of the post248and the clamps244. A stress wave moves through the workpiece W and into the plate240while the workpiece W is being secured. The raised portion242acts as an opposing anvil to the impacting by the driven member204on the surface206of the workpiece W.

FIG. 10is still another example of a support202for the workpiece W. Clamps260, which are elongated, are mounted against the surface206of the workpiece W. On the opposite side of the workpiece W, a clamp262is provided in opposition to one clamp260acting against the opposite surface of the workpiece W. An optional clamp264, which may also be elongated, is positioned against the opposite side of the workpiece W in opposition to the clamp260. A movable anvil266is mounted in opposition to the driven member204at the opposite side of the workpiece W. The anvil266is movable in X, Y and Z directions and acts in opposition to the impacting by the driven member204against the surface206. The workpiece W is secured and there is a reduced loss of energy of a stress wave that passes to the upper surface206of the workpiece W during impacting by the driven member204.

With reference toFIG. 11, there is still a further example of a support202for a workpiece W during processing as the driven member204is impacting the surface206of the workpiece W. An air bladder anvil268is provided on the opposite side of the surface206of the workpiece W from the driven member204as impacts are applied to the upper surface206. The air bladder anvil268, which may be elongated, has an adjustable shape during impacting. A pair of clamps270, which are elongated, bear against the upper surface206of the workpiece W. In some implementations, the clamps270can be used to impart pre-stress to the workpiece W. A reduced loss of energy results by holding the workpiece W while the air bladder anvil268backs up the workpiece W, and may absorb some of the energy.

Referring toFIG. 12, the structure of the support202is similar to that ofFIG. 11in that clamps274, which are elongated, bear against the surface206of the workpiece W. The air bladder anvil272of this example is a preformed shaped air bladder anvil, as opposed to the adjustable shape of the air bladder anvil268ofFIG. 11and functions in a similar manner as the example ofFIG. 11. The clamps274secure the surface206of the workpiece W to reduce energy loss.

As stated previously, referring toFIG. 13, a flow diagram is shown wherein a controller280(e.g., manipulator & end effector controller) is provided for operating a manipulator286and an end effector peening device284. The device210and the driven member204, which form part of the end effector peening device284, are mounted on the end effector peening device284for applying multiple impacts at a given frequency against the surface206of the workpiece W. The manipulator286locates the end effector and the driven member204while the driven member204moves across the workpiece W and while the driven member204impacts the surface206of the workpiece W. The workpiece W is represented as the part288. A position control290is also identified in the flow diagram ofFIG. 13. The method of operation for changing physical characteristics of the workpiece W or part288will be described with reference to the flow diagramFIG. 13. Each operating feature shown in the flow diagram will be briefly described along with each of their functions while referring also to previously described operating components.

The position control290locates the position of the workpiece W or part288positioned on a support202. Once the workpiece W is securely mounted on the support202, the position location of the workpiece W is communicated to the controller280. The controller280receives the workpiece W position and the path data from a system control (not shown in the flow diagram ofFIG. 13). The controller280drives a motion control system through a programmed path of travel. Additionally, the controller280communicates with the end effector peening device or driven member204at the current location of the end effector relative to the workpiece W. The manipulator286locates and controls the end effector to move in a preplanned motion path. The end effector peening device284causes the driven member204to apply multiple impacts to the workpiece W as commanded by the controller280. The driven member204moves across the coverage area of the surface206of the workpiece W while secured on a support202under the control of the end effector and the manipulator which are controlled by the parameters defined below.

In carrying out the method of using the described apparatus for applying impacts to a workpiece W, the workpiece W is securely positioned on a support202which may be any one of the above supports202. The position control290provides the controller280with the position of the workpiece W on the support202.

The controller280is provided with the adjustable parameters for changing physical characteristics of the workpiece W into a desired final product. The adjustable parameters for changing physical characteristics of the workpiece include an energy level for the impacts, which may be in the range of 1-35 Joules, on the workpiece W, a rate of the reciprocation of impacts on the workpiece W (e.g., the number of impacts being applied to the workpiece per unit time or beats per second), the coverage area of the impacts on the workpiece W, and linear or areal density of impacts (e.g., size of impactor surface, feed rate of manipulator, step-over distance, and area covered per unit time). The energy level for the impacts may be tied to the rate of application of the impacts on the workpiece W. Other parameters include the configuration of the pattern formed by the impacts as they are laid down onto the workpiece W and additional passes or impacts to the same portion of the workpiece W. The impacts are applied by the driven member204to the surface of the workpiece W as the end effector and manipulator move the driven member204across the entire coverage area or surface206of the workpiece W. This occurs when the entire workpiece W or a section thereof has been mounted in a secure position on a support202, as described above. The device210is mounted on the end effector. The driven member204of the device210is under the control of the controller280, which further includes the parameters. The impacting is continued until a desired final product has been achieved.

The basic components of both the apparatus and method of the present disclosure have been described above. In selected situations, an added method step and apparatus may be provided for initially pre-loading the workpiece W for forming the workpiece W into a preliminary contour. A description of the pre-loading of the workpiece W for forming a preliminary contour on a workpiece W is described below.

The following disclosure relates generally to impact peening following a pre-loading step. Here, the pre-loading provides a more efficient process, such as a shortened overall processing time, when the pre-loading is performed prior to impacting the workpiece W by the driven member204. The forming of the workpiece W can be accomplished with less power and with directional bias by the impacting of the workpiece W with the driven member204when the workpiece W has first been pre-loaded. For purposes of this application, pre-loading is synonymous with pre-stressing.

Referring toFIG. 6, it is schematically shown that by forcibly pressing on the concave side of a workpiece W, as illustrated by an arrow292, a desired contour is achieved that may be more than the ultimate contour for the workpiece W. As shown inFIG. 5, opposing grippers302are applied against the workpiece W, which are illustrated inFIG. 6by arrows294. As the impacts are applied to the surface206of the pre-stressed workpiece W by the driven member204, as represented by the arrow292, the part generally maintains its pre-loaded shape, while the pre-load force is partially offset by the preferential bending moments generated by the process in the part.

FIG. 4shows a fixture, generally300, that has elongated grippers302fixed at the upper outer portion of the fixture300and a threaded bolt304is located in the lower, central portion305of the fixture300. A workpiece W is formed in the fixture300by a forming member306, having a contoured upper surface on the underside of the workpiece W. The upper/outer zones of the upper surface of the workpiece W are being held by the grippers302as the bolt304forces the forming member306upwardly against the lower surface of the workpiece W to pre-load the workpiece W.

Referring toFIG. 5, an alternate fixture310is shown. Like the fixture300, the construction of the fixture310is substantially the same as fixture300exceptFIG. 5shows the use of a hydraulic piston assembly312that drives the forming member306against the lower surface of the workpiece W being pre-loaded in the fixture310. The hydraulic piston assembly312is fixed to the underside of the fixture310by an outer flange314having threaded bolts316secured to the underside of the fixture310. A piston rod318is secured to the underside of the contoured forming member306. Again, the upper/outer zones of the upper surface of the workpiece are being held by the grippers302as the piston rod318forces the forming member306upwardly against the lower surface of the workpiece to pre-load the workpiece W.

The workpiece W is first pre-loaded for forming a preliminary contour on the workpiece W, such as shown inFIGS. 4, 5 and 6, that does not exceed the elastic limit of the workpiece W. While pre-loaded, the workpiece W or a section of a workpiece is processed by applying multiple impacts from the driven member204against the convex side of the workpiece W. The processing of the pre-loaded workpiece W is continued in the manner described above relative to multiple impacts applied by the driven member204with the impacts being applied to the convex side of the workpiece W, such as seen inFIGS. 4 and 5.

Referring toFIG. 16A, in some embodiments, the driven member204, or impactor, includes a shaft400with an impact end402. The shaft400can have any of various sizes and cross-sectional shapes. In the illustrated embodiment, the shaft400is cylindrical. More specifically, the shaft400can be elongate in a lengthwise direction (e.g., parallel to a driving direction430shown inFIGS. 17A-Cand parallel to the central axes of the shaft400shown inFIGS. 16A-16B) and has a substantially circular cross-sectional shape. The shaft400protrudes lengthwise from a proximal end directly coupled to a metal peening machine to the impact end402, otherwise known as a distal end of the shaft. The impact end402, in the illustrated embodiment, defines a substantially flat surface that remains parallel to the surface of the workpiece W being impacted by the driven member204. In other words, the flat surface of the impact end402is substantially perpendicular to a driving direction430of the driven member when driven by the metal peening machine. The driving direction430is defined as the direction of the motion of the driven member204as it is driven into contact with the workpiece W. Accordingly, as defined, the driving direction430is perpendicular to the surface of the workpiece W being impacted by the driven member204. The flat surface of the impact end402can have the same shape as the cross-sectional shape of the shaft400, which in the illustrated implementation is circular. In some implementations, the impact end402may be defined by a non-flat surface, such as a spherically radiused surface.

As defined herein, the driven member204includes the shaft400, the impact end402, and the impact features as described below. As shown inFIG. 1, the driven member204can include structure directly or integrally coupled to a drive mechanism, such as the device210. For example, in some implementations, the shaft400, impact end402, impact features, and structure directly coupled to the drive mechanism, can be formed as a single, monolithic, and one-piece unit to form the driven member204.

Alternatively, the driven member204can be formed separately from the structure directly coupled to the drive mechanism, and coupled to the structure. For example, the driven member204can be a pin or impactor that is removably secured to a structure directly coupled to the drive mechanism. In such implementations, the driven member204, or the shaft400of the driven member, may include features (e.g., flutes, splines, notches, etc.) for coupling the driven member to a drive mechanism. The driven member204can be removably coupled to the drive mechanism via a coupling mechanism, such as a quick-release mechanism.

Coupled to and protruding from the impact end402of the shaft400is one or a plurality of impact features410A. Each of the impact features410A defines an impact surface412A, which directly contacts the surface of the workpiece W when impacted by the driven member204. In other words, because the impact features410A protrude from the impact end402of the shaft400, only the impact surfaces412A of the impact features directly impact the workpiece W. Accordingly, in some implementations, the impact end402of the shaft does not contact the surface of the workpiece W when impacted by the driven member204. The impact features410A can be coupled to the impact end402by being co-formed with the shaft400to form a one-piece monolithic construction with the shaft. Alternatively, the impact features410A can be formed separately from the shaft400and later coupled to the shaft.

The impact surfaces412A can have any of various peripheral shapes. As defined herein, the peripheral shape of an impact surface is the shape of a periphery of the impact surface, and does not refer to the flatness or curvature of the impact surface. In other words, the peripheral shape of an impact surface is the shape of the impact surface when viewed perpendicularly from a plane parallel to the impact end402or perpendicular to the driving direction430, such as the view inFIGS. 18A, 18B, and 20A-D. The peripheral shape of each impact surface412A of the impact features410A is circular and symmetrical. However, as will be described below, the peripheral shape of the impact surfaces412A can be non-circular and/or asymmetrical.

Each impact surface412A of the impact features410A can have a contour shape that is flat or non-flat (e.g., curved or rounded). In other words, as an impact surface extends within its peripheral shape, the contour of the impact surface may be flat or non-flat. As defined herein, the contour shape of an impact surface of an impact feature is the shape of the impact surface when viewed perpendicularly from a plane perpendicular to the impact end402or parallel to the driving direction, such as the view inFIGS. 17A-C. As will be described below in more detail, in some implementations, such as shown inFIGS. 19A-C, the impact surfaces of the illustrated impact features are substantially flat. However, in other implementations, such as shown inFIGS. 16A-C, the impact surfaces of the illustrated impact features are substantially rounded to form domed or hemispherical bumps. More specifically, referring toFIG. 17A, each impact surface412A of the features410A has a contour shape that is substantially curved. The curvature of the contour of the impact surface412A helps to distribute the impact energy from the driven member204to the workpiece W and change the physical characteristics of the workpiece W in a more efficient and controlled manner.

Although the impact end402of the shaft400has a plurality of impact features410A each with a round peripheral shape and curved contour shape, in some implementations, such as shown inFIG. 3, the impact end of the shaft can have a single impact feature410A with a round peripheral shape and curved (e.g., rounded, domed, hemispherical, etc.) contour shape. The single impact feature410A of such an implementation may define an impact surface412A with a curved contour shape having a radius between a radius of the shaft400and a radius much larger than the radius of the shaft.

The plurality of impact features410A of each driven member204can include two or more impact features arranged about the impact end402of the shaft400in any of various patterns. The patterns can be symmetrical patterns or non-symmetrical patterns. As defined herein, a pattern is symmetrical if the pattern is symmetrical about at least one line (e.g., line of symmetry) parallel to the impact end402, and non-symmetrical if the pattern is not symmetric about any line parallel to the impact end. Additionally, the patterns may include uniformly spaced or non-uniformly spaced impact features. Impact features of a pattern are uniformly spaced if the spacing or distance between directly adjacent impact features is the same.

Referring toFIGS. 16A-C, the plurality of impact features410A are uniformly spaced about the impact end402in different symmetrical patterns420A-C, respectively. As shown inFIG. 16A, the pattern420A includes three impact features410A uniformly spaced apart about the impact end402in a symmetrical manner. Like the pattern420A, the patterns420B,420C of impact features410A inFIGS. 16B and 16C, respectively, also are symmetrical with uniformly spaced impact features. However, unlike the pattern420A, the pattern420B has a higher quantity of impact features410A than the pattern420A, and a single impact feature centrally located on the impact surface402. The pattern420C is similar to the pattern420B, but with a higher quantity of impact features410A.

As shown inFIG. 16C, in some implementations, the driven member204may include an impact head404coupled to the shaft400. The impact head404defines an impact end402similar to the impact ends402ofFIGS. 16A and 16B. However, the impact head404is sized bigger than the shaft404to define a larger cross-sectional area than the shaft400, and thus a larger impact end402. In some implementations, the larger impact end402of the impact head404is conducive to accommodating patterns with higher quantities of impact features. The impact head404can be separately formed and attached to the shaft400, or formed together with the shaft400to form a monolithic one-piece construction.

The uniform spacing of the impact features410A results in a uniform distribution of impacts, which may provide a substantially uniform distribution of energy to the workpiece W, but does not provide directionality to the transmitted energy. Rather, in certain implementations, directionality of the transmitted energy is supplied via pre-loading the workpiece W as described above.

Referring toFIG. 18A, the plurality of impact features410A are non-uniformly spaced about the impact end402of the shaft400in a symmetrical pattern420E. Similar toFIGS. 16A-C, the impact features410A of the pattern420E each has an impact surface with a round or circular peripheral shape. However, the distances between directly adjacent impact features410A of the pattern420E vary. For example, the distance between directly adjacent impact features410A along a diameter of the impact end402is smaller than the distance between directly adjacent impact features about the periphery of the impact end. Notwithstanding the non-uniform spacing of the impact features410A, the pattern420E is still symmetrical about at least one line extending parallel to the impact end402(e.g., along a diameter of the impact end).

The non-uniform spacing of the impact features410A of the pattern420E, and other patterns with non-uniformly spaced impact features, may help to provide directionality to the energy transmitted to the workpiece W from the driven member204. For example, non-uniform spacing of the impact features410A results in non-uniform distribution of energy to the workpiece W, which if controlled properly can assist in deforming the workpiece W in a particular manner or direction. Providing directionality to the transmitted energy via the configuration of the impact features reduces, and in some instances eliminates, the need for pre-loading the workpiece W. Accordingly, configuring the impact features of the driven member204to provide directionality assists in reducing the complexity, cost, and efficiency of metal peening metallic workpieces. The symmetry of the pattern420E results in a symmetrical distribution of the energy into the workpiece W and a symmetrical deformation of the workpiece W. It is recognized that the symmetrical pattern420E with non-uniform spacing of the impact features410A shown inFIG. 18Ais merely one example, and that in other examples any of various other symmetrical patterns with non-uniform spacing of the impact features can be used.

Now referring toFIG. 18B, the plurality of impact features410A are non-uniformly spaced about the impact end402of the shaft400in a non-symmetrical pattern420F. Similar to the pattern420E, the non-uniform spacing of the pattern420F can assist in deforming the workpiece W in a particular manner or direction. However, unlike the pattern420E, use of the pattern420F results in a non-symmetrical distribution of the energy into the workpiece W, and thus a non-symmetrical deformation of or dent in the workpiece W. AlthoughFIG. 18illustrates one particular embodiment of a non-symmetrical pattern420F with non-uniform spacing of the impact features410A, in other embodiments, other non-symmetrical patterns with non-uniform spacing of the impact features can be used.

Although the shape of the impact features410A of the patterns inFIGS. 16A-C,18A, and18B is the same, in some embodiments, the size of the impact features410A of the patterns may be different. The height of an impact feature can be defined as the distance between the impact surface402and a distal end of the impact feature, or the distance the impact feature protrudes from the impact surface. Alternatively, the height of an impact feature may be defined as a distance away from a plane perpendicular to the driving direction430of the driven member204. Referring again toFIG. 17A, the heights of the impact features410A of the illustrated pattern are the same. However, as shown inFIG. 17B, the heights of the impact features410A of the illustrated pattern are different with a middle one of the impact features having a height greater than the heights of the adjacent two impact features. In other words, at least one of the impact features410A of the pattern inFIG. 17Bprotrudes a distance D1away from the impact surface402and at least one of the impact features of the same pattern protrudes a different distance D2away from the impact surface. In the illustrated embodiment, the distance D1is less than the distance D2. Varying the heights of the impact features as shown inFIG. 17Bmay help to promote directionality of the impact energy transmitted into the workpiece W as discussed below.

Directionality of the impact energy can also be promoted by configuring the impact features to have impact surfaces with asymmetrical contour shapes. The contour shapes of the impact surfaces412A of the impact features410A are symmetrical about a line extending parallel to the driving direction430as shown inFIGS. 17A and 17B. However, referring toFIG. 17C, the contour shapes of impact surfaces412B of the impact features410B are asymmetrical about a line extending parallel to the driving direction430. Although one particular asymmetrical shape is shown inFIG. 17C, the impact features can have impact surfaces with any of various asymmetrical contour shapes.

The patterns described above, as illustrated inFIGS. 16A-C,18A, and18B, include a plurality of impact features410A each with an impact surface412A having a round or circular peripheral shape. In fact, as illustrated, every impact feature410A of the patterns ofFIGS. 16A-C,18A, and18B has an impact surface with a round peripheral shape. However, in some embodiments, the driven member204may have an impact feature with an impact surface that has a non-round peripheral shape. For example, referring toFIG. 19A, the driven member204has a single impact feature410C with an impact surface412C having a square peripheral shape. In other words, the periphery of the impact surface412C is square. Furthermore, the contour shape of the impact surface412C is substantially flat in the illustrated embodiment. Although in other embodiments, the contour shape of the impact surface412C can be round or curved. In yet certain implementations, most of the impact surface412C has a contour shape that is flat, with the edges defining the transition between sides of the impact feature410C and the impact surface412C being radiused. The square peripheral shape of the impact surface412C may act to impart at least some directionality to the energy transmitted into the workpiece W upon impact with the workpiece W. For example, the energy transmitted to the workpiece W proximate the corners of the square peripheral shape of the impact surface412C is greater than proximate the sides of the square peripheral shape.

According to another example, as shown inFIG. 19B, the driven member204has an impact feature410D with a single impact surface412D having a rectangular peripheral shape. The rectangular shape of the periphery of the impact surface412D enhances the directionality of the energy transmitted into the workpiece W by distributing more of the energy to the elongated sides of the rectangular shape than at the ends.

Referring toFIG. 19C, the driven member204includes a plurality of impact features410E each with an impact surface412E having a square peripheral shape. The impact features410E are arranged in a pattern420D. Although the pattern420D includes three impact features410E uniformly spaced about the impact surface402in a symmetrical manner similar toFIG. 16A, in some embodiments, the driven member204can have any of various symmetrical or non-symmetrical patterns of impact features410E uniformly or non-uniformly spaced about the impact surface402, such as shown and described above.

Now referring toFIGS. 20A-C, a driven member204may include a plurality of impact features each with an impact surface having any of various non-round peripheral shapes. For example, inFIG. 20A, the driven member204includes a pattern420G of at least one impact feature410A with a round impact surface412A and at least one impact feature410F with a non-round impact surface412F. In other words, the pattern420G includes impact features with a first peripheral shape and impact features with a second peripheral shape that is different than the first peripheral shape. The non-round peripheral shape of the impact surfaces412F of the illustrated impact features410F is ovular (e.g., elliptical or racetrack shaped) and can be symmetric. Similar to the rectangular shape of the impact surface412D of the impact feature410D shown inFIG. 19B, the ovular shape of the impact surface412F of each impact feature410F may facilitate directionality of the energy transmitted into the workpiece W by distributing more of the energy towards the elongated sides of the ovular shape than at the smaller radiused ends of the ovular shape. Further, the use of impact features with differently-shaped impact surfaces in the pattern420G may help to facilitate directionality of the energy transmitted into the workpiece W by creating a non-uniform distribution of the energy.

As another example, referring toFIG. 20B, the pattern420H includes a plurality of impact features410G with impact surfaces412G having a different non-round peripheral shape compared to the impact surfaces412F of the impact features410F. Each of the impact features410G forms a long, thin ridge that extends across the impact surface402from one side of the impact surface to an opposing side of the impact surface. Although not necessary, in the illustrated embodiment, the ridges of the impact features410G extend linearly and are arranged parallel to each other in a spaced-apart manner. The ridges can be symmetrical as shown. Further, in the illustrated embodiment, the ridges of the impact features410G have different lengths with the lengths of the ridges getting smaller away from a central ridge extending diametrically across the impact surface402. Although not shown, in some implementations, the ridges are not linear, but curve as they extend across the impact surface402. The elongate, thin peripheral shape of the impact surfaces412G of the illustrated impact features410G facilitates directionality of the energy transmitted into the workpiece W.

In yet another example, referring toFIG. 20C, the pattern420I includes a plurality of impact features410H with impact surfaces412H having a non-round and non-symmetric peripheral shape. Although the illustrated impact surfaces412H have a distinct non-symmetrical peripheral shape, in other embodiments, the impact surfaces can have any of various other non-symmetrical peripheral shapes based on a desired directionality of the energy transmitted into the workpiece W. Further, although the driven member204includes a pattern of a plurality of impact features with non-symmetrical shapes, it is recognized that in some embodiments a driven member may include only a single impact feature with a non-symmetrical shape.

As mentioned above, the use of a plurality of impact features on the impact surface402of the driven member204, as opposed to a single impact surface, distributes the impact energy from the driven member across the plurality of impact surfaces. Because the entirety of the impact energy from the driven member is not concentrated on a single impact surface, but rather is spread out over multiple impact surfaces, the impact energy transmitted into the workpiece W by each impact surface is less than the overall impact energy provided by the driven member. Accordingly, the threat of over-impacting the workpiece W by imparting too much impact energy to the workpiece W, thereby damaging the workpiece W, is reduced with the use of a plurality of impact features. The higher the quantity of impact features, the greater the distribution of the impact energy, or the lower the amount of impact energy imparted to the workpiece W by each individual impact feature. Additionally, in some implementations, the higher the quantity of impact features, the more uniform the appearance on the surface of the workpiece W following an impact.

In view of the foregoing, in some embodiments, such as shown inFIG. 20D, the impact surface402of the shaft400may be textured to optimize the distribution of the impact energy. The textured impact surface402of the shaft400ofFIG. 20Dis formed by a pattern420J of impact features protruding from the impact surface. The configuration of each impact feature of the pattern420J can be similar to any of the various impact features as discussed above. For example, as shown, the pattern420J can include a plurality of impact features410A with impact surfaces having a round peripheral shape. However, in contrast to the illustrated patterns shown and described above, the pattern420J has a significantly higher quantity of impact features. The quantity of the impact features of the pattern420J is high enough to give off the appearance of a textured surface. For example, the pattern420J may have a quantity of impact features equal to or greater than 100 to 10,000 impact features. The impact features of the pattern420J can have impact surfaces with peripheral shapes that are symmetrical or non-symmetrical, and the pattern420J can be symmetrical or non-symmetrical, to facilitate directionality of the impact energy as has been discussed above in detail.

In some embodiments, a metal peening machine that includes a metal peening device, such as device210, is used to drive into a workpiece W a driven member204with at least one impact feature as described above. The metal peening machine may include a plurality of driven members each with one or more differently configured impact features that are interchangeably coupleable to the metal peening machine to be driven into a workpiece W. Although the impact features are configured differently, each of the driven members include identical machine coupling features that allow each of the driven members to be coupled to the metal peening machine in the same manner. Accordingly, each of the plurality of driven members can be interchangeably coupled to the metal peening machine.

According to certain embodiments, a method of using the metal peening machine to deform a metal workpiece W includes setting impact characteristics of the metal peening machine in response to the configuration of the impact feature(s) of the driven member. In other words, in some implementations, the impact characteristics of the metal peening machine are tied (e.g., proportional) to the configuration of the impact feature(s) of the driven member. Because a driven member with multiple impact features distributes impact energy over multiple impact surfaces, the metal peening machine can be set to impart a higher overall impact energy or impact reciprocation rate to the workpiece W without plastic deformation of the workpiece W reaching an undesirable depth into the workpiece W. In some instances, the overall impact energy or impact reciprocation rate of the driven member imparted by the metal peening machine would result in plastic deformation of the workpiece W reaching an undesirable depth into the workpiece W with a conventional driven member without an impact feature as disclosed herein.

In one implementation of the method, the metal peening machine is driving, at a first overall impact energy, first impact reciprocation rate, first feed rate at which the manipulator moves the end effector, and a first step-over distance between rows of impacts, a first driven member with a first configuration of at least one impact feature into a workpiece W. The combination of impact reciprocation rate and feed rate results in an overall impacts applied per distance traveled over the workpiece W, which, when coupled with the step-over distance, is closely related to overall impact energy. Then, the first driven member is replaced with a second driven member with a second configuration of at least one impact feature. Before driving the second driven member into the workpiece W, at least one of the first overall impact energy, first impact reciprocation rate, first feed rate, and first step-over distance is changed to a second overall impact energy, second impact reciprocation rate, second feed rate, and second step-over distance, respectively. With the metal peening machine set to impart the second overall impact energy, second impact reciprocation rate, second feed rate, or second step-over distance, the metal peening machine then drives the second driven member into the workpiece W. The second overall impact energy can be more or less than the first overall impact energy, the second impact reciprocation rate can be more or less than the first impact reciprocation rate, the second feed rate can be more or less than the first feed rate, and the second step-over distance can be more or less than the first step-over distance. In one implementation, the second configuration of the at least one impact feature includes more impact features than the first configuration, and either the second overall impact energy is higher than the first overall impact energy, the second impact reciprocation rate is higher than the first impact reciprocation rate, the second feed rate is lower than the first feed rate, or the second step-over distance is smaller than the first step-over distance. Although overall impact energy, impact reciprocation rate, feed rate, and step-over distance have been discussed, other impact characteristics of the metal peening machine can be set in response to the configuration of the impact features of the driven member.

Alternatively, in some implementations of the method, when a change to the deformation characteristics is desired, either the impact characteristics of the metal peening machine are changed with the same driven member, or the impact characteristics of the metal peening machine are held constant and the driven member is switched to another driven member with a different impact feature configuration.