Patent Application
20080019795
Although it will be understood there are various ways of making some of the products described and changes can be made to the form of invention which will now be described, a pair of inventive, slightly different designs will now be illustrated.
Referring now to
The first component of this assembly 10 is a metal sleeve generally designated 12 as shown to include a lower, thread-free portion 14, an exterior threaded portion 16, and a flange portion 18. The sleeve includes a bottom wall 20 and a flat top portion 22. There is defined an elongated interior wall 24, and a shortened interior wall portion 26. These walls 20, 26 leave a pocket 28 which optionally contains a magnet or a magnetic material to attract small metal filings from the engine itself. The elongated interior wall 24 and the top flange 22 define most of the volume of the engineered thermoplastic core 30, which also includes a shank portion 31 and also a head portion 32 having a hexagonal well 34 to accommodate an allen wrench, while the exterior of the wall 30 includes a hex pattern 36.
The plastic material 30 also has a stub flange 38 extending therefrom and this includes a pocket 40 to create a gripping surface and the thermoplastic material also surrounds the stub flange 38 at the bottom 39, with the thermoplastic material underlying and completely surrounding the metal sleeve flange 18. It is important that the walls 24 are of a non-circular configuration, thus ensuring that the sleeve will turn with the core 30.
Outside of the stub flange 38 is an exterior flange made from a thermoplastic vulcanizate generally designated 42 and shown to include an upper, radially extending surface 44, a beveled surface 46, an exterior cylindrical surface 48, and a lower radially extending surface 50. The portion 42 includes a small cleat 52 to insure gripping and includes a bead 54 on the bottom surface 50 thereof, to provide a deformable jacket for sealing purposes.
Referring now to
Sufficient space is provided for the engineered thermoplastic core generally designated 130, and which includes a shank portion 131, and a head portion 132 of somewhat different configuration than its counterpart in
Referring now to the manner of molding the head portion 132 and the shank portion 131 of the engineered thermoplastic material, two mold halves are shown to close over the flange portions 118 of the sleeve 112. These mold halves include a lower portion or mold half 160 and an upper mold half 162, and include a sprue 164 shown in the middle of the upper mold part 162. The glass-filled thermoplastic material is injection molded, and acquires the shape provided by the somewhat schematically shown two mold halves 160 and 162. Since the material is thermoplastic, it requires no curing, and the molding is done in a matter of seconds.
Another important feature of the invention is the manner in which the exterior flange generally designated 143 is made. This method involves so-called “overmolding”, with part of the mold being used to form one part of the finished product, and the previously formed plastic surface used to form the remainder of the product. The finished overmolded product is inherently bonded to the previously molded product. Thus, there are two molded shapes involved, with each shape being partially embodied in the final product. This flange has an upper surface 145, a lower surface 147, a gasket cleat or rib 149, and an enlarged diameter exterior flange 151. These portions are formed in the mold halves 153, 155, and are created by injecting the thermoplastic vulcanizate through the sprue 157 in the upper mold half 155.
The particular material used in the core 131 and the head 132 as well as the stub flange 138, etc. is an injection molded, material with a 50% glass fiber content dispersed in a semi-crystalline polyamide, with a partially aromatic co-polyamide forming a part thereof. These materials are somewhat analogous to nylon, and they feature high stiffness and strength, and great dimensional stability. These materials have good chemical resistance and are able to provide a good, polished surface finish.
The injection is shown somewhat systematically, but typically the material has a melting point of about 260° C. This material has a density of about 1.50 to 1.60 and has about 1.3% to 1.5% moisture absorption at 23° C. and 50% relative humidity. The resulting nylon head formation and shank portion are eminently suitable for use in the heavy duty environment anticipated. The somewhat square interior walls 124 provide for more than adequate torque transmission, and in a typical application, the head portion has a width of 15 millimeters for a 12 to 13 millimeter shank.
The covering of the stub flange with an exterior flange generally designated 143 is accomplished by using a thermoplastic vulcanizate. In other words, the material used in this phase of the manufacture can be molded with the rib portion 149 internally formed on the outer flange 151. This outer flange material is a thermoplastic elastomer, which is made from a high performance, previously cross-linked elastomer which is dispersed very finely in a high performance thermoplastic elastomer.
This material is made from an ethylene acrylic elastomer, and a thermoplastic ether ester elastomer. This material, unlike ordinary rubber which must be cross-linked to become effective, uses standard thermoplastic processing techniques, such as injection molding. The parts do not need to be post cured, resulting in much lower cycle times, and therefore, higher productivity. The material is obtained in ready-to-use compounded form, and does not require any plasticizers or the like.
The material is lower in price than high performance rubbers. As a result of using this material in injection molding, the matter is very much simplified in relation to awaiting curing that would be required with ordinary rubbers.
The drain bolt of
Both of these drain plug devices do away with the need to prepare the metal for bonding with the elastomer, which is naturally adhesive to the core material. The illustrated examples provide the option of using a magnetic component in the bottom opening. The bolt head, being made entirely from plastic, is free from rust and will ultimately limit the torque applied, if necessary. The bolt head may be made from a colored material and thus has the additional advantage of identifying a supplier.
The cost is less than that of its predecessor, because the threaded sleeve cost is considerably less than a finished, all-steel bolt. The time to manufacture is greatly reduced, since thermoplastic methods of molding and overmolding create a cycle time which is considerably less than that required of ordinary rubber. There is no exposed metal and consequently there cannot be any rust with the inventive product.
As a result of the design, there is almost no way in which the oil pan with which this drain bolt is associated could be damaged. The overmolding method saves not only time, but expense, since, as pointed out, the overmolding method uses a portion of the thermoplastic core as the other portion of the mold.
It will thus be seen at the present invention provides a new product and a method of making it, having a number of advantages and characteristics, including those pointed out and others which are inherent in the invention.
