From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Letter from General Bakelite Company regarding designs for a commutator mold.
| Identifier | ExFiles\Box 39\3\ Scan195 | |
| Date | 1st September 1922 | |
| Copy X3573 GENERAL BAKELITE COMPANY Division of Bakelite Corporation 8 West 40th Street, NEW YORK September 1, 1922. Subject: Commutator Mold Rolls-Royce of America, Inc., Springfield, Massachusetts. Attention Mr. M.{Mr Moon / Mr Moore} Olley, Eng. Gentlemen: x2494 X3573 We have yours of the 24th ultimo addressed to Mr. Gordon. We enclose herewith our blue print No. 159 in which two designs of die are shown for molding Bakelite commutators. Figure 1 shows the type used when molding a commutator with a pre-formed bricquette or biscuit of compressed molding material. Design 2 shows the type used when the loose powder is used without preforming. The pre-formed or #1 design has the advantage in that it permits the molding material to be pressed in from both ends of the commutator. That is, a compressed biscuit as shown in the upper right hand corner is placed on top of plunger "D" and another on top of the ring "C" so that as the top plunger "B" is forced home the material fluxes and is pressed into the commutator sector, insuring a very dense and homogeneous piece. Sometimes re-enforcing steel end plates are used for this type of construction, as marked in red pencil in the upper left hand corner of blue print. This biscuit method of molding requires a separate mold or "pre-forming" die for compressing the loose powder into biscuits. In cases where commutators are fairly large and there is plenty of clearance between the center bushing and the commutator sectors, it will not be necessary to mold from both ends. The proper charge of material can be poured in from the top of mold as shown in design #2 and pressed home with plunger "B". When using molds of this design it is not necessary to use pre-formed biscuits. Of course, you appreciate that the spring ring "C" is designed to hold the copper sectors properly insulated from | ||