This disclosure relates to water jet cutting fixtures and more specifically to water jet cutting fixtures for forming a plurality of cuts into a workpiece, and a method of manufacturing a serpentine resistance heater disk by forming a plurality of slits into the heater disk.
Electrical resistance heaters are one option to provide supplemental heat into an internal combustion engine's exhaust aftertreatment system for enabling fast light-off of a downstream catalytically-loaded component (e.g., catalytic converter) of the exhaust aftertreatment system. One type of electrical resistance heater employs a series of slits extending alternatingly into the heater from opposite sides of the body of the heater to provide a serpentine electrical path through the heater body that increases the resistance across the heater and thereby enables the heater to generate heat via Joule heating when a voltage is applied to the heater. The slits that define the serpentine pattern must be formed into the heater body during manufacture of the serpentine resistance heaters, which can add complexity and cost to the manufacturing process.
Disclosed herein are fixture assemblies for slitting a workpiece into a serpentine body. In embodiments, a fixture assembly comprises a patterned support section comprising a plurality of support slats interspaced with gaps; and a holder plate comprising an opening configured to receive the workpiece and positioned atop the patterned support section such that intended cutting locations in the workpiece are positioned directly above the gaps in the patterned support section and the slats are positioned directly below uncut portions of the serpentine body after cutting the workpiece.
In embodiments, the patterned support section is part of a support plate positioned below the holder plate.
In embodiments, the support plate is secured to the holder plate via one or more fasteners.
In embodiments, the fixture assembly further comprises a removable support element on which the patterned support section is located and the support plate comprises a receptacle shaped and sized to removably receive the removable support element therein.
In embodiments, at least one outer edge of the removable support element has a lip that rests on a corresponding lip of a corresponding edge of the receptacle.
In embodiments, one of the holder plate and the support plate comprises one or more calibration pins and the other of the holder plate and the support plate comprises one or more calibration holes, each calibration hole corresponding to and arranged to receiving one of the calibration pins.
In embodiments, the fixture assembly comprise a plurality of the calibration pins and a plurality of the calibration holes, wherein the calibration pins are located a fixed distance from each other and the calibration holes are also located the fixed distance from each other.
In embodiments, the support plate comprises the one or more calibration pins and the holder plate comprises the one or more calibration holes.
In embodiments, the workpiece has a honeycomb configuration that comprises an array of intersecting walls that define channels extending axially therethrough.
In embodiments, the holder plate comprises a plurality of segments that are movable with respect to each other, and the opening in the holder plate is formed together by the plurality of segments such that relative movement of the segments causes change in shape or size of the opening.
In embodiments, the fixture assembly further comprises one or more positioning mechanisms between one or more adjacent pairs of the segments to control relative movement therebetween.
In embodiments, each positioning mechanism comprises a threaded rod connected between the corresponding adjacent pair of segments and that causes relative movement between the adjacent pair of segments when the threaded rod is rotated.
In embodiments, the fixture assembly further comprises one or more locking nuts to fix the relative position of the adjacent segments by preventing rotation of the threaded rod when tightened.
In embodiments, the holder plate comprises at least one clamp that is selectively engagable with the workpiece to prevent vertical movement of the workpiece when the workpiece is positioned in the opening.
In embodiments, the holder plate comprises one or more grippers that are radially movable into and out of the opening to engage against an outer periphery of the workpiece when the workpiece is in the opening.
In embodiments, wherein the support plate comprises a trench defining a plurality of fastener locations about the outer periphery of the workpiece, that enable angular alignment of the holder plate to the support plate.
Also disclosed herein are cutting systems. In embodiments, a cutting system comprises a fixture assembly according to an embodiment of any of the preceding paragraphs positioned with respect to a water jet cutting tool for enabling the water jet cutting tool to slit the workpiece held by the fixture assembly.
Also disclosed herein are methods for forming a serpentine body with a water jet cutting system. In embodiments, a method comprises positioning a workpiece in an opening of a holder plate and on top of a patterned support section that comprises a plurality of support slats interspaced with gaps such that intended cutting locations for creating slits in the workpiece are positioned directly above the gaps in the patterned support section; cutting a plurality of slits through the workpiece along the intended cutting locations with a water jet cutting tool of the water jet cutting system without cutting into the patterned support section to create the serpentine body from the workpiece, wherein the slats are positioned directly below uncut portions of the serpentine body after the workpiece is cut.
In embodiments, the method further comprises inserting a removable support element that comprises the patterned support section into a receptacle of a support plate, wherein the holder plate is secured atop the support plate.
In embodiments, the method further comprises affixing the support plate to the water jet cutting system, wherein the support plate comprises a calibration pin extending therefrom; aligning the holder plate with respect to the support plate by inserting the calibration pin through a calibration hole in the holder plate when the holder plate is positioned atop the support plate; calibrating a reference coordinate for the water jet cutting system with respect to the calibration pin; and determining a location of one or more of the opening, the workpiece, the intended cutting locations, the slats, or the gaps based on the reference coordinate.
It is to be understood that both the foregoing general description and the following detailed description are merely exemplary, and are intended to provide an overview or framework to understanding the nature and character of the claimed subject matter. The accompanying drawings are included to provide a further understanding and are incorporated in and constitute a part of this specification. The drawings illustrate one or more embodiment(s), and together with the description, serve to explain principles and operation of the various embodiments.
Reference will now be made in detail to exemplary embodiments which are illustrated in the accompanying drawings. Whenever possible, the same reference numerals will be used throughout the drawings to refer to the same or like parts. The components in the drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the exemplary embodiments.
Numerical values, including endpoints of ranges, can be expressed herein as approximations preceded by the term “about,” “approximately,” or the like. In such cases, other embodiments include the particular numerical values. Regardless of whether a numerical value is expressed as an approximation, two embodiments are included in this disclosure: one expressed as an approximation, and another not expressed as an approximation. It will be further understood that an endpoint of each range is significant both in relation to another endpoint, and independently of another endpoint.
Serpentine bodies can be used in a variety of applications, such as resistance heater bodies for providing supplemental heat in an exhaust aftertreatment system for an internal combustion engine. The formation of a serpentine body requires a plurality of slits in the body that define the serpentine patterned by isolating, breaking, severing, or otherwise preventing electrical connection between portions of the body on opposite sides of the slits. In some manufacturing techniques the slits can be formed directly during manufacture of the body itself, such as via three-dimensional printing. However, if a body is instead extruded or formed in some other manner, it is more practical to form the slits in a separate manufacturing step after formation (e.g., extrusion) of the body. For example, extrusion may be used to form a honeycomb body, while weaving may be used to form a mesh or screen, or a foaming process may be used to form a foamed body. In any such case, the honeycomb, mesh, screen, or foam workpiece will need to be slit to create a serpentine body therefrom.
A common step during water jet cutting is to make a one-time use sacrificial fixture to hold the part need to be cut. However, the creation of sacrificial fixtures is too costly and time consuming to be not practical for the industrial manufacture of individual serpentine bodies. However, support of the workpiece during slitting to create serpentine bodies is necessary since the uncut segments of the serpentine body extending between each adjacent pair of slits will sag, droop, or bend after slitting, and be increasingly prone to vibration as more slits are made in the workpiece.
In various embodiments, the disclosed embodiments provide for fixtures and methods for facilitating the slitting of workpieces as part of a process for manufacturing serpentine bodies, such as those used as resistance heaters. Advantageously, the embodiments disclosed herein provide for reusable fixtures, as well as those that can be variably adjusted in size to accommodate a variety of different sized or shaped workpieces. Additionally, the embodiments disclosed herein advantageously provide sufficient support to the serpentine segments of the workpiece as the workpiece is slitted to ensure consistent clean cuts are made in the workpiece during the entire serpentine slitting process by reducing or eliminating sagging, drooping, bending, and/or vibration of the segments of the workpiece throughout the entire slitting process.
As best seen in the enlarged portion of
Referring back to
The holder plate 22 comprises an opening 26 that is configured to receive the workpiece 10 therein. The opening 26 can be shaped and sized to complementarily receive the workpiece 10 therein. The opening 26 can comprise cutouts 27 that facilitate gripping of the sides of the workpiece 10 (e.g., by a worker, tool, or robotic gripping implement) in order to facilitate placement of the workpiece 10 into the opening 26 and/or removal of the workpiece 10 from the opening 26. As described in more detail below, the support plate 24 comprises a patterned support section 28 positioned below the opening 26 that provides support to the underside of the workpiece 10 as the workpiece 10 is cut by the system 100. As described in more detail below, the patterned support section 28 comprises a pattern that complementarily corresponds to the intended cutting pattern to be made into the workpiece 10.
The holder plate 22 can further optionally comprise one or more clamps 30 that are movably or releasably engageable with the top side of the workpiece 10 when the workpiece 10 is positioned in the opening 26, such as by pinning the workpiece 10 against the support plate 22 or otherwise preventing vertical movement of the workpiece 10 during cutting. In this way, the holder plate 22 provides support to prevent lateral or horizontal movement of the workpiece 10, while the support 24 provides a surface upon which the workpiece 10 rests, and optionally the clamps 30 prevent vertical movement out of the opening 26, to securely hold the workpiece 10 in place during cutting.
An example of the patterned support section 28 is shown in more detail in
For example, the outline of the serpentine body 12 and slits 14 are shown in dashed lines overlaid on top of the patterned support segment 28 in
To facilitate prevention of the support section 28, the gaps 34 can have a width w (dimension between adjacent slats 32) that is at least as wide as the corresponding width of the slits 14 intended to be cut into the workpiece 10 during formation of the serpentine body 12. In some embodiments, the gaps 34 are wider than the width of the slits 14, such as at least 50% wider than the slits 14, at least twice as wide as the slits 14, or even at least three times as wide as the slits 14. In this way, the gaps 34 prevent inadvertently cutting through the support section 28 even if the cutting operation is not perfectly straight, if the workpiece 10 vibrates or slightly moves during cutting, and/or to accommodate a variable cutting width of the cutting system 100 during the cutting operation (e.g., a water jet cutting operation may not create perfectly straight cuts and/or cuts that are exactly the same width from top to bottom of the cut).
To assist in holding the support sections 28 in place in the receptacle 38, one or more outer edges of the removable support element 36 can have a lip, shelf, or flange 40 as shown in the enlarged portion of
In the embodiment of
Additionally, in the embodiment of
When the holder plate 22 comprises multiple of the segments 46, the segments 46 can be moved relative to each other by positioning mechanisms 48. For example, in the embodiment of
In either case, the pins 56 and the holes 58 are a fixed distance L from each other. For example, as described above, the cutting system 100 can comprise a camera or vision system that is used to determine a location of the workpiece 10 to assist in cutting. When using such a camera or vision system, the pins 56 and/or holes 58 can be used as a reference location or coordinate that enables the cutting system 100 to quickly determine the location of components of the fixture assembly 20, and therefore of the workpiece 10, based on calibration with respect to the reference location set by the calibration pins 56. In this way, the very time-consuming step of recalibrating and aligning reference points with the cutting tool 102 for each and every workpiece that needs to be slitted is avoided. For example, the support plate 24 can first be fixed with respect to the cutting system 100 and the water jet cutting tool can be aligned with a center of one of the pins 56 to establish the reference coordinate, such as a single origin point and/or with as a line passing through the centers of both pins for orientation of a reference coordinate axis (e.g., the x-axis).
Since the opening 26 and the receptacle 38 are at a fixed locations relative to the pins 56 and holes 58 and the workpiece 10 is positioned within the opening 26, the location of the workpiece 10 is also accurately set with respect to the cutting pattern. Advantageously, this alignment of the cutting system 100 to the support plate 24 only needs to be done once at the beginning of a cutting operation, with the holder plate 22 and/or removable support elements 38 able to be swapped out any number of times for cutting any number of workpieces without losing this alignment, since the holder plate 22 and the support section 28 are automatically aligned to the support plate 24 via the pins 56 and holes 58 when reinstalled in the fixture assembly 20.
It will be apparent to those skilled in the art that various modifications and variations can be made without departing from the spirit or scope of the claimed subject matter. Accordingly, the claimed subject matter is not to be restricted except in light of the attached claims and their equivalents.
This application claims the benefit of priority under 35 U.S.C. § 119 of U.S. Provisional Application Ser. No. 63/416,660 filed on Oct. 17, 2022, the content of which is relied upon and incorporated herein by reference in its entirety.
Number | Date | Country | |
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63416660 | Oct 2022 | US |