Plastic and nonmetallic article shaping or treating: processes – Mechanical shaping or molding to form or reform shaped article – To produce composite – plural part or multilayered article
Reexamination Certificate
1999-06-15
2004-09-21
Eashoo, Mark (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
Mechanical shaping or molding to form or reform shaped article
To produce composite, plural part or multilayered article
C264S271100, C264S272110, C264S272150
Reexamination Certificate
active
06793863
ABSTRACT:
FIELD OF INVENTION
This invention is related generally to a process for making automotive parts and, more particularly, to a process for producing a spark plug boot resistor assembly.
BACKGROUND OF THE INVENTION
The manufacture of spark plug boot resistor assemblies has been a costly and complicated procedure involving several steps. Typically to make a spark plug boot resistor assembly, two halves of an outer heat and radio frequency shield are stamped out and a silicon rubber boot is compression molded and cured. Next, a resistor is inserted into the interior of the silicon rubber boot. Once the resistor is positioned within the silicon rubber boot, the halves of the outer heat and radio frequency shield are placed around the silicon rubber boot and are crimped together.
Although this process for manufacturing a spark plug boot resistor assembly works, it has a number of problems. For example, the process requires that the silicon rubber boot be manufactured prior to any assembly. The process for manufacturing a silicon rubber boot is complicated requiring several operations and some complex tooling and handling. As a result, the overall cost of manufacturing spark plug boot resistor assemblies is increased while the overall production throughput is decreased because of the additional steps required. Additionally, the process requires the shield to be installed after the resistor is inserted into the silicon rubber boot. This additional step also adds to the overall cost of manufacturing spark plug boot resistor assemblies while reducing overall production throughput.
Another problem with prior processes for manufacturing spark plug boot resistor assemblies is with the installation of the resistor in the silicon rubber boot. The fit between the resistor and the silicon rubber boot is not always precise. As a result, gaps may be formed between the resistor and the silicon rubber boot which provide a space for fluid to seep in and corrode the resistor. Additionally, since a resistor must be inserted into each silicon rubber boot, the precise location of the resistor within the boot will vary from boot to boot. Since the points of connection to the ends of the resistor are located inside of the silicon rubber boot, if the location of the resistor varies then a connector may not be able to reach and properly connect to one end of the resistor.
SUMMARY OF THE INVENTION
A process for producing a spark plug boot resistor assembly in accordance with one embodiment of the present invention includes a few of steps. First a mold is provided and a shield is positioned in the mold. The shield is made of a metallic material and has a substantially tubular shape. Next, a resistor is positioned inside the shield and the mold. Once the shield and the resistor are in place in the mold, a rubber material is injected into the mold between the shield and the resistor. Once the rubber material has cured, then the spark plug boot resistor assembly is removed from the mold.
A process for producing a spark plug boot resistor assembly in accordance with another embodiment of the present invention also includes a few steps. First, a mold is provided and then a shield is positioned in the and a resistor is positioned inside the shield. Next, a material is injected into the mold between the shield and the resistor. The mold is designed to form first passages in the material adjacent opposing ends of the shield. Each passage extends to one end of the resistor and along a portion of the side of the resistor. Once the material has cured, then the spark plug boot resistor assembly is removed from the mold.
A process for producing a spark plug boot resistor assembly in accordance with yet another embodiment of the present invention also includes a few steps. First, a mold with a first portion and a second portion is provided. Next, a shield is positioned in the first portion of the mold and then a resistor is positioned inside the shield in the first portion of the mold. Once the shield and the resistor are in place, then the second portion of the mold is closed over the first portion of the mold. Next, a material is injected into the mold between the shield and the resistor. Once the material has cured, the second portion of the mold is separated from the first portion of the mold and then the spark plug boot resistor assembly is removed from the first portion of the mold.
The process for producing a spark plug boot resistor assembly in accordance with the present invention provides a number of advantages. For example, the process is less complicated and as a result is less expensive and has a higher overall production throughput than prior processes. The process does not require the silicon rubber boot to be formed prior to the assembly of the resistor within the heat and radio frequency shield. Instead, the boot is formed with the resistor in place. This eliminates several operations and some complicated tooling and handling. Additionally, the process does not require the additional step of crimping the shield around the silicon rubber boot.
Another advantage of the present invention is with the sealing and positioning of the resistor within the shield. Unlike past processes which required the resistor to be inserted into a preformed boot, with the present invention the boot is formed around the resistor. As a result, a tight seal is formed between the resistor and the boot which minimizes and/or prevents any fluid from leaking in and causing the resistor to corrode. Additionally with the present invention, the resistor is more precisely positioned within the boot each time a spark plug boot resistor assembly is formed than is possible when the resistor is inserted into the boot As a result, the connection points at the ends of the resistor will always be at the same location, thus reducing the chance of an improper connection.
Another advantage of the present invention is the ability to precisely form passages in the material injected between the shield and the resistor which are used to mate with other automotive parts. Not only can the passages be formed which extend in to the ends of the resistor, but these passages can be formed to extend in past the ends of the resistor and around a portion of the side of the resistor. The portions of these passages along the side of the resistor help to ensure a good connection between the resistor and a connector extending into the passage in the material. With prior processes, these passages extending past and along the side of the resistor were not feasible because they would make the spark plug boot resistor assembly susceptible to leakage. Additionally, since the boot is formed after the shield and the resistor are in place in the mold, it is possible to form additional passages between the shield and the injected material at each end of the shield. These passages can be used to assist in the connection between the spark plug boot resistor assembly and other automotive components. Similarly, these additional passages were not feasible with prior processes because the shields were crimped around the silicon rubber boot after the resistor is inserted. As a result, it would be very difficult to precisely control the crimping to create the right space for these passages consistently.
Yet another advantage of the present invention is the use of a split mold which simplifies the manufacturing process. With the split mold the resistor and shield can be more easily installed and removed from the mold during manufacturing.
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patent: 5145433 (199
Himes, II J. Mark
Miller John C.
Eashoo Mark
Lexington Insulators
Nixon & Peabody LLP
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