Patent Application
20120088619
This application is generally related to chains and more particularly related to the outer plates of chains.
Chains and chain drive systems are widely used in various mechanical applications, including the automotive field. A typical chain drive uses a chain to transmit power from a driving gear to a driven gear. Drive chains such as roller chains and silent chains, also known as inverted toothed chains, are generally constructed using only plates and pins. As the chain passes over a gear, the teeth of the gear interact with the openings between the links of the chain or teeth formed on the links of the chain. A typical roller chain or silent chain is held together solely by a press-fit between the outermost plates and the pins, with the inner plates acting as articulating links. Such roller chains and silent chains are usually formed through a continuous operation. First, a top outer plate having two bores is press-fitted onto the top ends of two pins. Next, two top inner plates, each having two bores, are each arranged around one of the two pins with a slip-fit so that each top inner plate is offset from the top outer plate by one pin. A middle plate having two bores is then arranged around the two pins with a press-fit or a slip-fit, the middle plate being aligned with the top outer plate. Two bottom inner plates, each having two bores, are also each arranged around one of the two pins with a slip-fit such that the two bottom inner plates are aligned with the two top inner plates. Finally, a bottom outer plate having two bores is press-fitted onto the bottom ends of the two pins to form one link of the chain.
Since the only press-fit holding each link of the chain together is between the top and bottom outer plates and the pins, it is desirable to increase the minimum amount of force required to remove the outer plates from the pins. This force is also known as the press out force, which is generally a function of the load-carrying contact area between the bores of the outer plates and the pins. One way of increasing the press out force is by increasing the thickness of the outer plates, which results in longer bores with larger contact areas. However, doing so also increases the size, weight, and cost of the chain. Another method of increasing the press out force is by using a shaving or fine blanking operation to form the bores in the outer plates instead of regular blanking. During a regular blanking operation, the bores are formed through a single punching process. However, the shear forces of punching result in a breakout area that is larger than the desired size of the bore. The breakout area decreases the load-carrying contact area of the bores and does not contribute to the press-fit between the outer plates and the pins. To reduce this breakout area, a shaving operation can be used. The bores are first formed through a regular blanking process using a smaller diameter punch, then the bores are shaved by using a second punch to remove a small amount of material. This reduces the breakout area and obtains better dimensional accuracy, but requires an additional step and thus increases the time and cost of construction. To further reduce the breakout area and increase the press out force, a fine blanking operation can be used instead of regular blanking or regular blanking and shaving. During fine blanking, the breakout area is minimized by compressing the outer plate and using an upper and lower punch to form the bore in a process that is more like extrusion than typical punching. While fine blanking increases the load-carrying contact area of the bores, it is expensive, time consuming, and requires special equipment. Therefore, a need exists for a chain that has an outer plate with reduced thickness and increased press out force, but is simple and inexpensive to construct
An outer plate for a chain is disclosed, the outer plate having two bores each adapted to receive an end of a pin. Each bore has an inner wall with a layer of imbedded abrasive material. In other embodiments of the outer plate, the abrasive material can be aluminum oxide or silicon oxide. In addition, each of the bores can have a diameter of approximately 4 mm and the outer plate can have a thickness of less than 1.3 mm.
A chain is also disclosed having pins, each having a first end and a second end, and first and second outer plates press-fitted around the first and second ends of each of the pins, respectively. Each of the first outer plates has two bores through which the first ends of respective ones of the pins extend, and each of the second outer plates has two bores through which the second ends of respective ones of the pins extend. Each of the bores of the first and second outer plates has an inner wall with a layer of imbedded abrasive material. The chain further includes inner plates disposed between the first and second outer plates, each of the inner plates having two bores arranged around respective ones of the pins with a slip fit. In other embodiments of the chain, the inner plates can include first and second inner plates and middle plates disposed between the first and second inner plates. The first and second outer plates are aligned with the middle plates, and the first and second inner plates are aligned with each other and offset by one pin from the middle plates. The abrasive material can be aluminum oxide or silicon oxide.
A method of forming an outer plate for a chain is also disclosed. The method includes the steps of providing a plate, forming two bores in the plate through blanking, and forming a layer of embedded abrasive material in an inner wall of each bore, preferably by tumbling the plate with a solution containing the abrasive material and a tumbling media. For sake of brevity, this summary does not list all aspects of the present invention, which is described in further detail below.
The foregoing summary, as well as the following detailed description of the preferred embodiments of the invention will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there is shown in the drawings embodiments which are presently preferred. It should be understood, however, that the invention is not limited to the precise arrangement shown.
Certain terminology is used in the following description for convenience only and is not limiting. The words “inner,” “outer,” “top,” and “bottom” designate directions in the drawings to which reference is made. A reference to a list of items that are cited as “at least one of a, b, or c” (where a, b, and c represent the items being listed) means any single one of the items a, b, or c, or combinations thereof. The terminology includes the words specifically noted above, derivatives thereof, and words of similar import.
As shown in
The layers of embedded abrasive material 36, 46 in the inner walls 34, 44 of the bores 32, 42 can be formed from any material having the suitable friction characteristics. For example and without limitation, the abrasive material can be aluminum oxide or silicon oxide, which are commonly used in steel finishing processes. As shown in
While the outer plates 30, 40 according to the present invention have been described in the context of a roller chain or silent chain, one of ordinarily skill in the art would appreciate that the present outer plates can be used in any chain where a large press out force is desired. For example, the present outer plates can also be used in a bushed chain, where the outer plates are press-fitted around bushings instead of pins. The layers of embedded abrasive material formed in the inner walls of the bores increases the friction between the inner walls of the bores and the outer surface of the bushings, thus maximizing the press out force between the outer plates and the bushings.
A method of forming the outer plates 30, 40 of the present invention is also disclosed, including the following steps. First, a plate is provided. The plate may be formed from any suitable material, such as steel. Two bores are formed in the plate through blanking. Preferably, a regular blanking operation is used to reduce the cost of forming the outer plate. A layer of embedded abrasive material is then formed in an inner wall of each bore by tumbling the plate with a solution containing the abrasive material and a tumbling media. The solution can be, for example and without limitation, a mixture of water and aluminum oxide, which is commonly used to finish steel. Alternatively, the solution can be a mixture of water and silicon oxide. The tumbling media can be of any material, size, or shape that is suitable for embedding the abrasive material into the inner walls of the bores, and may vary depending on the material and dimensions of the particular outer plate being formed. For example and without limitation, the tumbling media can be in the form of balls each having a diameter of approximately 2 mm-3 mm, which is suitable where the bores of the outer plate each has a diameter of approximately 4 mm. The balls can be formed from steel or glass. During the tumbling process, the tumbling media support and embed the abrasive material into the inner walls of the bores. In addition, the contact between the tumbling media, the solution containing the abrasive material, and the outer plate during tumbling de-burrs the outer plate, eliminating the need for an additional finishing process. As discussed above, the layer of imbedded abrasive material in the inner wall of each bore increases friction between the inner walls of the bores and pins arranged within the bores, which increases the press out force between the outer plate and the pins. The present method of forming an outer plate decreases the time and cost of construction as well as the required thickness of the outer plate. Given a bore diameter of approximately 4 mm, an outer plate formed by the present method can have a thickness of less than 1.3 mm, and as low as 0.9 mm.
Having thus described various embodiments of the present outer plate and resulting chain in detail, it is to be appreciated and will be apparent to those skilled in the art that many physical changes, only a few of which are exemplified in the detailed description above, could be made in the apparatus and method without altering the inventive concepts and principles embodied therein. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore to be embraced therein.
This application claims the benefit of U.S. Provisional Application Ser. No. 61/390,801, filed Oct. 7, 2010, which is incorporated by reference as if fully set forth herein.
| Number | Date | Country | |
|---|---|---|---|
| 61390801 | Oct 2010 | US |
