Patent Application
20140326116
The subject matter herein relates generally to die components for press devices.
A press device typically includes a base assembly that holds a workpiece and a punch assembly movable by a press ram toward the workpiece and base assembly to form the workpiece therebetween. The press device is configured for high speed stamping having many cycles per second. The workpiece, which is positioned between the base assembly and punch assembly, is formed during the pressing operation. A stripper plate is typically positioned between the base assembly and the punch assembly to pin the workpiece against the base assembly as the punch assembly is retracted.
Die components are typically held by the punch assembly and/or base assembly to form the workpiece. The die components have a predetermined profile that is used to by punch, stamp, shear, cut, bend or otherwise manipulate the shape and/or profile of the workpiece. Conventional die components have problems associated with pressing characteristics of the die components and the workpiece. For example, the die components tend to cause burrs on the edges of the workpiece during blanking as the die components punch through the workpiece. The forces exerted on the die components during repetitive pressing causes wear and damage to the die components, which may also lead to further edge quality problems.
A need remains for a press device having improved pressing characteristics.
In one embodiment, a press device is provided including a base assembly having a base die component configured to form a workpiece and a punch assembly movable relative to the base assembly during a pressing operation. The punch assembly has at least one punch die component pressing the workpiece to form the workpiece. The punch die component includes a main body having a workpiece engagement surface configured to engage the workpiece formed by the base assembly and the punch assembly. The punch die component having a vibration generator operatively coupled to the main body. The vibration generator causes the main body of the die component to vibrate at a high frequency during the pressing operation.
Optionally, the vibration generator may include a piezoelectric actuator. The vibration generator may include an electrical element and a piezoelectric element configured to change shape when voltage is applied to the electrical element. The vibration generator may cause ultrasonic vibration of the main body.
Optionally, the press device may include a spacer coupled to the main body with the vibration generator sandwiched between the spacer and the main body. The press device may include a preload bolt coupled between the spacer and the main body. The preload bolt may connect the spacer to the main body. The preload bolt may compress the vibration generator between the spacer and the main body. Vibration of the vibration generator may be transmitted into the main body. The spacer may be fixed relative to the punch assembly. Vibration of the vibration generator may cause the main body to move relative to the spacer.
Optionally, the workpiece engagement surface may be configured to vibrate against the workpiece during the pressing operation. The punch assembly may be moved along a press stroke and a return stroke during the pressing operation. The vibration generator may cause the main body to vibrate against the workpiece multiple times during the press stroke. The workpiece engagement surface may directly engage the workpiece. Optionally, the main body may include a removable punch. The removable punch may define the workpiece engagement surface. The removable punch may be configured to directly engage the workpiece.
In another embodiment, a punch die component for a press device is provided that includes a main body extending between a first end and a second end with a workpiece engagement surface at the second end configured to engage a workpiece formed by the press device. A vibration generator is coupled to the first end of the main body. The vibration generator operates to cause the main body to vibrate at a high frequency during a pressing operation of the press device. A spacer is coupled to the main body at a spaced apart position. The vibration generator is sandwiched between the spacer and the first end of the main body.
In another embodiment, a method of operating a press device is provided. The method includes positioning a workpiece between a base assembly and a punch assembly of the press device, holding a punch die component at the punch assembly, pressing the punch die component into the workpiece to form the workpiece during a pressing operation of the press device, and vibrating the punch die component against the workpiece at a high frequency during the pressing operation.
A base assembly 110 is supported on the press bed 108. The base assembly 110 supports the workpiece 102 from below during the pressing operation. The press device 100 includes a punch assembly 112 above the base assembly 110. The punch assembly 112 is driven by a press ram 114 during a pressing operation toward and/or away from the base assembly 110 to press the workpiece 102 to form the component. Optionally, the punch assembly 112 may be spring biased away from the base assembly 110. Alternatively, the punch assembly 112 may be pulled away from the base assembly by the press ram 114. In an exemplary embodiment, the punch assembly 112 includes punch die components, generally shown at 116, that are used to form the workpiece 102. The die components 116 may be the components that engage the workpiece and form the workpiece. Optionally, the base assembly 110 may include one or more base die components, which may be similar to the punch die components 116.
In an exemplary embodiment, the base assembly 110 includes a base shoe 120 supported by the press bed 108 and a base block 122 mounted to the base shoe 120. Optionally, the base block 122 may have a predefined profile for forming a certain type of component from the workpiece 102. The base block 122 may be replaced by a different base block having a different profile to change the type of component manufactured by the press device 100. Alternatively, the base block 122 may hold one or more removable die components that engage and form the workpiece. The base assembly 110 may include any number of base blocks 122 and/or die components.
In an exemplary embodiment, the punch assembly 112 includes a punch shoe 124 and a punch block 126 coupled to the punch shoe 124. The punch block 126 and/or the punch shoe 124 may be cam driven, spring driven or movable by other means relative to the base assembly 110 during the pressing operation. The press ram 114 is used to force the bunch block 126 and/or punch shoe 124 toward the base assembly 110 during the pressing operation. The punch block 126 may have a predefined profile to form a certain type of component from the workpiece 102. The punch block 126 may be replaced by a different punch block having a different profile to form a different type of component from the workpiece 102. In an exemplary embodiment, the punch block 126 holds one or more of the die components 116 that directly engage the workpiece to form the workpiece.
In an exemplary embodiment, the base assembly 110 includes a stripper plate 130 between the base block 122 and the punch block 126. The workpiece 102 is feed between the stripper plate 130 and the base block 122. The stripper plate 130 pins the workpiece 102 in position during the pressing operation. The stripper plate 130 is positioned to engage the workpiece 102 during withdrawal of the punch block 126 to prevent distortion of the component and/or workpiece 102 and/or to release the workpiece 102 from the punch block 126. The stripper plate 130 pins the workpiece 102 against the base block 122 to strip the workpiece 102 from the punch assembly 112. Optionally, the stripper plate 130 may be used to locate the die components 116 during the pressing operation. For example, the die components 116 may pass through the stripper plate 130 and the stripper plate 130 may hold the side-to-side position of the die components 116 relative to the workpiece 102. Optionally, the die components 116 may be hold by the stripper plate 130 rather than the punch block 126.
During operation, the workpiece 102 is formed between the base block 122 and the punch block 126. The punch shoe 124 is engaged by the press ram 114 and is driven toward the base assembly 110 during the pressing operation of the press device 100. The die components 116 are pressed into the workpiece as the punch shoe 124 and punch block 126 are forced downward. The press assembly 112 may be subjected to many pressing cycles per second. In an exemplary embodiment, the punch die components 116 may vibrate as the die components 116 are pressed against the workpiece 102, which enhances the pressing operation and forming of the workpiece 102. For example, the die components 116 may be vibrated at high frequency to enhance the pressing operation and forming of the workpiece 102. The die components 116 may be vibrated many times during each press stroke of the pressing operation. The die components 116 may be vibrated at ultrasonic frequencies. The vibration of the die components 116 may make shearing or cutting through the workpiece 102 easier. The vibration of the die components 116 may reduce burrs on the edges of the workpiece 102. The vibration of the die components 116 may enhance the edge quality of the edges of the workpiece 102. The vibration of the die components 116 may induce less stress on the die components 116. The vibration of the die components 116 may reduce wear on the die components 116. The vibration of the die components 116 may allow blanking of thinner material as the die clearances do not need to be maintained at such precise locations when the die components 116 are vibrated during the pressing operation.
The die component 116 includes a vibration generator 150 coupled to the first end 142 of the main body 140. The vibration generator 150 is operated to cause the main body 140 to vibrate at a high frequency during a pressing operation of the press device 100 (shown in
In an exemplary embodiment, the vibration generator 150 includes a piezoelectric actuator 152. The piezoelectric actuator 152 changes shape when a voltage is applied to the piezoelectric actuator 152. For example, the piezoelectric actuator 152 may expand and contact at high frequency to cause ultrasonic vibration.
The die component 116 includes a spacer 160 coupled to the main body 140 at a spaced apart position. The vibration generator 150 is sandwiched between the spacer 160 and the first end 142 of the main body 140. A preload bolt 162 is used to secure the spacer 160 to the main body 140. In an exemplary embodiment, the main body 140 includes a threaded bore 164 and the preload bolt 162 is threadably coupled to the main body 140 in the threaded bore 164. The preload bolt 162 may be secured to the main body 140 by other means in alternative embodiments. The spacer 160 may be secured to the main body 140 by alternative means in alternative embodiments. In an exemplary embodiment, the preload bolt 162 is tightened to force the spacer 160 against the vibration generator 150. The vibration generator 150 is likewise pressed against the main body 140. The preload bolt 162 may be tightened such that the vibration generator 150 is partially compressed between the spacer 160 and the main body 140.
Vibration caused by the vibration generator 150 is transmitted directly into the main body 140 and/or the spacer 160. Optionally, the die component 116 may be positioned within the punch assembly 112 (shown in
In an exemplary embodiment, the piezoelectric actuator 152 includes piezoelectric elements 170, 172. The piezoelectric elements 170, 172 are fabricated from a material that is configured to change shape when voltage is applied across such material. For example, the piezoelectric elements 170, 172 may expand and/or contract depending on a polarization of the voltage applied across the piezoelectric elements 170, 172. In an exemplary embodiment, the piezoelectric elements 170, 172 are manufactured from a ceramic material and may be referred to hereinafter as ceramic elements 170, 172. The piezoelectric elements 170, 172 may be manufactured from other materials in alternative embodiments.
The piezoelectric actuator 152 includes electrical elements 174, 176 and a ground element 178. The electrical elements 174, 176 are positioned on the piezoelectric elements 170, 172, respectively. The ground element 178 is positioned between the piezoelectric elements 170, 172. Electrical leads, such as wires, may be electrically connected to the electrical elements 174, 176 to supply power to the electrical elements 174, 176. Any number of piezoelectric elements 170, 172, electrical elements 174, 176 and ground elements 178 may be provided in alternative embodiments. The piezoelectric elements 170, 172, electrical elements 174, 176 and ground elements 178 may have any shape and are not limited to the disc shape illustrated in
An insulator 180 is provided between the piezoelectric actuator 152 and the preload bolt 162. The insulator 180 may also be positioned between the piezoelectric actuator 152 and the spacer 160 and/or the main body 140. The insulator 180 provides electrical insulation between the piezoelectric actuator 152 and the corresponding metal components of the die component 116.
In an exemplary embodiment, during operation of the piezoelectric actuator 152, when voltage is applied to the electrical elements 174, 176, the piezoelectric elements 170, 172 expand or contract depending on the polarization of the voltage applied to the electrical elements 174, 176. The voltage polarization is repeatedly switched at high frequency, causing vibration of the piezoelectric elements 170, 172. Ultrasonic vibration can be achieved. Vibration in other frequency ranges can be achieved in other embodiments. The voltage is switched across the electrical connections at the electrical elements 174, 176 and the ground element 178. The insulator 180 provides insulation between the electrical connections and the sides of the piezoelectric elements 170, 172.
The insulator 180 provides electrical insulation between the piezoelectric elements 170, 172. The insulator 180 provides electrical insulation for the piezoelectric elements 170, 172 from the preload bolt 162. The insulator 180 provides electrical insulation for the piezoelectric elements 170, 172 from the masses defined by the spacer 160 and the main body 140.
The ultrasonic vibration is transmitted through the main body 140 attached to the end of the piezoelectric actuator 152. The spacer 160 is connected to the main body 140 through the preload bolt 162. Vibration of the spacer 160 may be transmitted to the main body 140 through the preload bolt 162. The preload bolt 162 applies a compressive load to the piezoelectric actuator 152 to hold the components together. In an exemplary embodiment, the mechanical resonance can be controlled by selecting the size of the masses of the main body 140 and spacer 160 relative to the piezoelectric elements 170, 172. For example, the size and shape of the masses may be selected to achieve a target oscillating frequency of the piezoelectric elements 170, 172. Optionally, the shape of the main body 140 can be designed to concentrate the ultrasonic vibration toward the workpiece engagement surface 146. For example, the second end 144 may have a smaller size as compared to the first end 142. The piezoelectric elements 170, 172 may be designed (e.g. sized, shaped, configured) so that the system attains mechanical resonance. Characteristics of the piezoelectric material affect the response to electric current. A material is selected so that characteristics and dimensions produce mechanical resonance with the masses at certain frequencies depending on the application.
In an exemplary embodiment, the workpiece engagement surface 146 may define a cutting face of the die component 116 and can have any shape desired to produce the blanking profile. In the illustrated embodiment, the workpiece engagement surface 146 is circular in shape; however other shapes are possible in alternative embodiments. In an exemplary embodiment, the main body 140 may be a single unitary body between the first end 142 and the second end 144. The workpiece engagement surface 146 is part of the unitary structure of the main body 140. In an alternative embodiment, the workpiece engagement surface 146 may be part of a separate component that is attached to a holder structure of the main body 140. The separate component may be replaceable to change the shape of the workpiece engagement surface 146 and thus change the blanking performed by the die component 116 without changing out other components of the die component 116.
The method includes holding 302 a punch die component at the punch assembly and pressing 304 the punch die component into the workpiece to form the workpiece during a pressing operation of the press device. The punch die component is held to engage the workpiece during the pressing operation. The punch die component may be generally fixed in position against a corresponding punch assembly component, such as a punch shoe, a punch block, a wear plate, a stripper plate, and the like, such that as the punch assembly is pressed toward the workpiece during a press stroke of the pressing operation, the punch die component engages and presses against the workpiece.
The method includes vibrating 306 the punch die component against the workpiece at a high frequency during the pressing operation. The vibrating may be caused by a vibration generator part of the punch die component. For example, a piezoelectric actuator may be attached to a body of the punch die component. The piezoelectric actuator has an electrical element and a piezoelectric element, such as a ceramic element. Voltage is applied to the electrical element to change shape of the piezoelectric element. The voltage may be quickly switched on/off or positive/negative to cause the piezoelectric element to vibrate. The vibration is transferred to the body of the punch die component. The punch die component may be vibrated at ultrasonic frequencies. The punch die component is vibrated against and/or through the workpiece during the pressing operation.
The die component is vibrated at high frequency to enhance the pressing operation and forming of the workpiece. The die component may be vibrated many times during each press stroke of the pressing operation. Optionally, the die component is only vibrated during the press stroke and is not vibrated during the return stroke of the pressing operation. Alternatively, the die component may be vibrated for at least a portion of the return stroke. The vibration of the die component may make shearing or cutting through the workpiece easier. The vibration of the die component may reduce burrs on the edges of the workpiece. The vibration of the die component may enhance the edge quality of the edges of the workpiece. The vibration of the die component may induce less stress on the die component. The vibration of the die components may reduce wear on the die component. The vibration of the die component may allow blanking of thinner material as the die clearances do not need to be maintained at such precise locations when the die component is vibrated during the pressing operation.
It is to be understood that the above description is intended to be illustrative, and not restrictive. For example, the above-described embodiments (and/or aspects thereof) may be used in combination with each other. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from its scope. Dimensions, types of materials, orientations of the various components, and the number and positions of the various components described herein are intended to define parameters of certain embodiments, and are by no means limiting and are merely exemplary embodiments. Many other embodiments and modifications within the spirit and scope of the claims will be apparent to those of skill in the art upon reviewing the above description. The scope of the invention should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. In the appended claims, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.” Moreover, in the following claims, the terms “first,” “second,” and “third,” etc. are used merely as labels, and are not intended to impose numerical requirements on their objects. Further, the limitations of the following claims are not written in means—plus-function format and are not intended to be interpreted based on 35 U.S.C. §112, sixth paragraph, unless and until such claim limitations expressly use the phrase “means for” followed by a statement of function void of further structure.
