Patent Application
20080241571
A chassis assembly is used in various environments. For example, a chassis can be used as an indoor enclosure or an outdoor enclosure on a utility pole, on the outside of building, in a vault underground, etc. In order to protect circuitry inside the chassis, the chassis needs to be sealed against elements in the environment, such as dust, corrosive airborne contaminates, or water. Furthermore, some chassis support modules often are coupled to the chassis. These chassis, therefore, use openings or windows to allow access to the interior of the chassis. These windows or openings also need to be sealed against elements in the environment.
Although current casting and machining technology enables the construction of chassis which meet the above criteria, it is desirable to reduce the costs and complexity of the chassis. For example, machining a chassis is significantly more expensive than casting. However, current casting techniques have other limitations, such as the ability to only cast a window in one wall of the chassis.
In one embodiment, a method of manufacturing a chassis is provided. The method comprises casting a first segment having a plurality of connected walls such that a window is cast in each of two of the plurality of connected walls in the first segment; casting a second segment having a plurality of connected walls such that a window is cast in each of two of the plurality of connected walls in the second segment; and coupling the first and second segments together to form the chassis having a window in four walls.
In another embodiment, a method of casting a segment of a chassis having a plurality of walls with a window in each of two of the plurality of walls is provided. The method comprises creating a mold including a cope and a drag such that the mold cavity formed when joining the cope and the drag defines a plurality of connected walls with a window in each of two of the plurality of connected walls; injecting molten material into the mold cavity; and separating the cope and the drag after the molten material has cooled to release the casted segment.
In yet another embodiment, a casting mold is provided. The casting mold comprises a cope; and a drag; wherein the cope and the drag are configured such that, when joined together, the cope and the drag form a molding cavity which defines a plurality of connected walls with a window in each of two of the plurality of connected walls; wherein the cope and the drag are further configured such that the parting plane of the casting mold is oriented at approximately a 45 degree angle from each of the two defined walls with a window.
In another embodiment, a chassis is provided. The chassis comprises a first casted segment comprising two side walls, a top wall, and a bottom wall which together define a continuous edge oriented at a 45 degree angle from each of the two side walls, each of the two side walls having a window; and a second casted segment comprising two side walls, a top wall, and a bottom wall which together define a continuous edge oriented at a 45 degree angle from each of the two side walls, each of the two side walls having a window; wherein the first and second casted segments are coupled together at the respective continuous edges to form the chassis.
In the following detailed description, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration specific illustrative embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that logical and/or mechanical changes may be made without departing from the scope of the present invention. It should be understood that the exemplary methods illustrated may include additional or fewer steps or may be performed in the context of a larger processing scheme. Furthermore, the methods presented in the drawing figures are not to be construed as limiting the order in which the individual steps may be performed. The following detailed description is, therefore, not to be taken in a limiting sense.
Embodiments of the present invention reduce the manufacturing costs of producing a chassis when compared to machining. In addition, embodiments of the present invention reduce the complexity of the chassis assembly. In particular, embodiments of the present invention enable a chassis to be cast in two segments. Each segment has two side walls with a window in each side wall. Current casting techniques lack this ability to cast a window in two sides of the same segment without complicated and expensive sliding cores. Therefore, a chassis according to embodiments of the present invention needs only one seal to couple the two segments and each window has a continuous seal around the perimeter of the window. Using one continuous seal around each window and to couple the two segments simplifies the assembly process and improves the ability of the chassis seal to block elements in the environment.
Around the perimeter of each window 110 is a seal 112. A groove 114 for seal 112 is machined out around the perimeter of each window 110 after the windows 110 are cast. Similarly, a seal 116 is placed in a groove 120 in edge 118 which extends along top wall 104, side walls 108 and bottom wall 106 in segment 102B. A similar groove is not located in edge 118 of segment 102A, in this embodiment. Seals 112 and seal 116 are o-ring seals in this embodiment. However, it is to be understood that other types of seals can be used in other embodiments.
Segments 102A and 102B are coupled together at their respective edges 118 as shown in
In other typical chassis, windows are formed by coupling two or more pieces or segments together with a portion of the window formed in each segment. However, this creates additional seams where the segments are coupled which need to be sealed. Casting edge 118 at an angle from side walls 108, as shown in
In addition, through use of seals 112 and 116, chassis 100 is submersible in water. In particular, in this embodiment, chassis 100 is designed to have an ingress protection (IP) rating of IP67 when completely sealed. The IP67 rating indicates that chassis 100 is dust tight and protects against the effects of immersing chasing 100 in water up to 1 meter.
Furthermore, casting edge 118 at an angle from side walls 108 enables windows 110 to be cast in each side wall 108 simultaneously. In a typical cast chassis, a window can only be cast in one side wall. This limitation is due to the fact that the mold used to cast the side walls only pulls apart in one direction. Therefore, the plane of a window to be cast typically lies perpendicular to the direction in which the mold is pulled apart. However, casting two side walls in each of segments 102A and 102B with edge 118 at an angle from each side wall enable casting a window in each side wall 108 as described in more detail below.
Casting windows 110 reduces the cost associated with manufacturing chassis 100 versus machining out windows 110. Additionally, segments 102A and 102B are identical when cast (that is, each is cast using the same mold). This further reduces cost by enabling the use of one mold rather than two separate molds. Some minor features, such as grooves 114 and 120, are then machined out of segments 102A and 102B after the segments are cast. Other features that are machines include tap holes and clearance holes. For example, since segments 102A and 102B are casted using the same mold, one segment is machined with tap holes and the other with corresponding clearance holes. Hence, the cost of manufacturing chassis 100 is reduced when compared to machining chassis 100 or using typical casting techniques. In addition, the number of necessary seals in chassis 100 is reduced when compared to chassis produced with typical casting techniques.
Casting mold 200 includes cope 202 and drag 204. Cope 202 and drag 204 are configured to form a molding cavity when joined which defines a plurality of connected walls with a window in each of two of the plurality of connected walls. In particular, in the cross-section view in
In addition, cope 202 and drag 204 are configured such that the parting plane 206 is oriented at an approximately 45° angle from surfaces 208 and 210. Cope 202 and drag 204 are separated in a direction perpendicular to parting plane 206 as indicated by arrows 212. Therefore, by orienting parting plane 206 at approximately 45° from surfaces 208 and 210, a window is cast in each of two walls defined by surfaces 208 and 210. Cope 202 defines the inner portion of the plurality of walls while drag 204 is configured to define the outer portion of the plurality of walls.
A cross-section view of a chassis segment 302 cast using casting mold 200 is shown in
The first and second segments are sand cast in this embodiment. However, other casting techniques, such as die casting, can be used in other embodiments. In addition, the first and second segments are each cast using the same mold in this embodiment. With regards to sand casting, using the same mold includes using the same tool or pattern to configure the cope and drag of the casting mold. Hence, the first and second segments are substantially identical when cast. Details of casting the first and second segments are discussed below with regards to
At 506, features are machined in the first and second segments. In this embodiment, a seal groove (e.g. groove 120) is machined in an edge (e.g. edge 118 in
At 510, the first segment is coupled to the second segment. The segments are coupled using screws which fit the tap and clearance holes machined in the first and second segments at 506. In particular, the first segment and second segments are coupled at the continuous edge which extends along the plurality of walls of the first and second segments respectively. The continuous edge in each of the first and second segments is cast at 502 such that it is oriented at a 45 degree angle from each of two side walls as shown in segment 102A in
At 604, molten material is injected into the mold. Exemplary molten material used in embodiments of the present invention includes, but is not limited to, iron, steel, bronze, brass, aluminum, and plastic. At 606, the cope and the drag are separated once the molten material has cooled to release the cast segment. In particular, the cope and the drag are separated in a direction perpendicular to the parting plane. As described above, by orienting the parting plane at a 45 degree angle from the walls with a window, a window can be cast in two walls simultaneously rather than in only one wall.
Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that any arrangement, which is calculated to achieve the same purpose, may be substituted for the specific embodiment shown. This application is intended to cover any adaptations or variations of the present invention. Therefore, it is manifestly intended that this invention be limited only by the claims and the equivalents thereof.
