|Publication number||US3709459 A|
|Publication date||Jan 9, 1973|
|Filing date||Nov 19, 1970|
|Priority date||Nov 21, 1969|
|Publication number||US 3709459 A, US 3709459A, US-A-3709459, US3709459 A, US3709459A|
|Original Assignee||Electric Power Storage Ltd|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (4), Referenced by (24), Classifications (12)|
|External Links: USPTO, USPTO Assignment, Espacenet|
United States Patent 1 Bushrod 51 Jan. 9, 1973  MOULD FOR CASTING ELECTRODE GRIDS FOR ELECTRIC STORAGE BATTERIES  Inventor: Charles James Buslirod, Bramhall,
England  Assignee: Electric Power Storage Limited, Clifton Junction, Lancashire, En gland 221 Filed: Nov. 19, 1970 21 Appl. No.: 90,889
 Foreign Application Priority Data Primary Examiner-R. Spencer Annear Attorney-Watson, Cole, Grindle & Watson  ABSTRACT NOV. 21, Great Britain A mould f sting lea r lead al oy lectrode g ids for electric storage batteries comprises backing plates  US. Cl ..249/134, 164/138 of metal faced with inserts of silicon nitride exposed to  Int. Cl ..B22c 1/12 the melt i o  Field of Search ..164/138; 249/114, 134;
l17/5.1 8 Claims, 1 Drawing Figure I IHHHH H MOULD FOR CASTING ELECTRODE GRIDS FOR ELECTRIC STORAGE BATTERIES This invention relates to casting lead or lead alloy electrode grids for electric storage batteries.
According to the present invention in a method of casting lead or lead alloy electrode grids for electric storage batteries at least the faces of the mould exposed to the melt comprise silicon nitride. Thus the mould may comprise inserts of silicon nitride backed by backing plates of metal such as cast iron.
In one form of the invention a method of making such a mould includes pressing silicon powder between punches at least one of which has in it a form corresponding to the desired casting, and thereafter heating it in an atmosphere of nitrogen.
An object of the invention is to enable lead or lead alloy battery plate grids to be cast without using mould dressing. A customary material for moulds for making such castings is meehanite cast iron, and the usual procedure is to spray the face of the mould with cork dust, generally about twice in each shift, in order to ensure filling of the mould. If such dressing is overlooked the mould is liable to fail to fill, and a large number of rejects may be obtained before the oversight is detected.
Although silicon nitride has a low co-efficient of expansion and, for a ceramic, a relatively high thermal conductivity, resulting in high resistance to thermal shock, its thermal conductivity compared with metals is relatively low. This is of substantial advantage in casting thin lead castings such as battery plates which consist virtually of a network of wires and involve liquid metal traversing long narrow passages in order to reach all parts of the casting. Due, it is believed, to the low thermal conductivity of silicon nitride, it is found that the mould dressing can be omitted without producing a faulty casting that would result from this with a cast iron mould. V
In addition the cork dressing assists the casting to part from the mould. It is found that the casting parts readily and clearly from the mould face of silicon nitride so that in this respect also the use of this material for the facing of the mould eliminates the need for mould dressing.
Silicon nitride is sufficiently hard to stand up to the wear involved.
In some cases it may be found that the reduction of thermal conductivity is more than is required and the cooling of the casting may be unduly delayed. In this event the cooling of the mould may be increased by providing a layer of metal foil, (e.g. copper foil), of high conductivity, between the silicon nitride inserts and the backing plates.
The invention may be put into practice in various ways but one specific embodiment will be described by way of example with reference to the accompanying drawing which is a sectional elevation of a mould for casting lead or lead alloy electric storage battery plate grids.
The mould includes a pair of silicon nitride facing plates 10 and 11 sandwiched between a pair of meehanite cast iron backing plates 16 and 17. Each facing plate is bevelled along two or more edges, and correspondingly bevelled clamping plates 24 and 25 are screwed, by screws 20 and 21 to the associated backing plate 16 or 17 to hold the facing plate in position. Each facing plate is provided with venting holes 12 and 13 and asbestos paper seatings 18 and 19 are interposed between the opposed faces of the backing plates 16 and 17 and facing plates 10 and 11. The usual alignment dowels 22 extend through the backing plates 16 and 17, in which they fit, and through the clamping plates 24 and 25 in which they have a clearance.
If undue delay is experienced in the warming up of the mould when casting is started, the mould may be pre-heated.
It is believed that, perhaps by eliminating the need for dressing, the use of silicon nitride moulds gives improved surface finish to the castings, resulting in reduced corrosion rate of grids and improved overcharge life.
What we claim as our invention and desire to secure by Letters Patent is:
l. A mould for casting lead or lead alloy electrode grids for electric storage batteries in which the faces of the mould exposed to the melt comprise inserts of silicon nitride which are backed by backing plates 0 metal.
2. A mould as claimed in claim 1 in which the backing plates are of cast iron.
3. A mould as claimed in claim 1 which includes a layer of metal foil, of high conductivity, between the silicon nitride inserts and the backing plates.
4. A mould as claimed in claim 3 in which the metal foil is copper foil.
5. A mould as claimed in claim 1 which includes asbestos paper between the silicon nitride inserts and the backing plates.
6. A mould as claimed in claim 2 which includes asbestos paper between the silicon nitride inserts and the backing plates.
7. A mould as claimed in claim 3 which includes asbestos paper between the silicon nitride inserts and the backing plates.
8. A mould as claimed in claim 4 which includes asbestos paper between the silicon nitride inserts and the backing plates.
|Cited Patent||Filing date||Publication date||Applicant||Title|
|US2992127 *||Dec 23, 1958||Jul 11, 1961||Texas Instruments Inc||Novel graphite articles and method of making|
|US3286312 *||Mar 29, 1965||Nov 22, 1966||Little Inc A||Refractory coated casting mold|
|US3580328 *||May 12, 1969||May 25, 1971||Gen Motors Corp||Mold for improved control of heat transfer in casting plate or strip products|
|AU200405A *||Title not available|
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US4130157 *||Jul 19, 1976||Dec 19, 1978||Westinghouse Electric Corp.||Silicon nitride (SI3 N4) leachable ceramic cores|
|US4195002 *||Jul 27, 1978||Mar 25, 1980||International Lead Zinc Research Organization, Inc.||Water-dispersible coatings containing boron nitride for steel casting dies|
|US4546951 *||Aug 16, 1983||Oct 15, 1985||Arbo Gereedschapsmakerij B.V.||Mould for encapsulating parts of elements into a plastic material|
|US4614630 *||Apr 2, 1984||Sep 30, 1986||Minnesota Mining And Manufacturing Co.||Mold having ceramic insert, method for injection molding using the same|
|US4704079 *||Apr 11, 1986||Nov 3, 1987||Minnesota Mining And Manufacturing Company||Mold having ceramic insert|
|US4903753 *||Mar 27, 1986||Feb 27, 1990||Varta Batterie Aktiengesellschaft||Casting technique for lead storage battery grids|
|US5326652 *||Jan 25, 1993||Jul 5, 1994||Micron Semiconductor, Inc.||Battery package and method using flexible polymer films having a deposited layer of an inorganic material|
|US6782940||May 29, 2001||Aug 31, 2004||Romain L. Billiet||Method for rapid reproduction of molds and mold components|
|US7583192||Dec 11, 2006||Sep 1, 2009||Keystone Technology Solutions, Llc||Radio frequency identification device and method|
|US7746230||Aug 30, 2007||Jun 29, 2010||Round Rock Research, Llc||Radio frequency identification device and method|
|US7839285||Aug 29, 2007||Nov 23, 2010||Round Rock Resarch, LLC||Electronic communication devices, methods of forming electrical communication devices, and communications methods|
|US7948382||Sep 11, 2006||May 24, 2011||Round Rock Research, Llc||Electronic communication devices, methods of forming electrical communication devices, and communications methods|
|US8018340||Oct 24, 2006||Sep 13, 2011||Round Rock Research, Llc||System and method to track articles at a point of origin and at a point of destination using RFID|
|US8802282||Jun 25, 2013||Aug 12, 2014||Water Gremlin Company||Battery parts having retaining and sealing features and associated methods of manufacture and use|
|US9190654||Mar 25, 2014||Nov 17, 2015||Water Gremlin Company||Battery parts and associated systems and methods|
|US9748551||Jun 29, 2012||Aug 29, 2017||Water Gremlin Company||Battery parts having retaining and sealing features and associated methods of manufacture and use|
|US20050242964 *||Jul 5, 2005||Nov 3, 2005||Tuttle John R||Miniature radio frequency transceiver|
|US20070007345 *||Sep 11, 2006||Jan 11, 2007||Tuttle Mark E||Electronic communication devices, methods of forming electrical communication devices, and communications methods|
|US20070103316 *||Dec 11, 2006||May 10, 2007||Tuttle John R||Radio frequency identification device and method|
|US20070290862 *||Aug 29, 2007||Dec 20, 2007||Tuttle Mark E||Electronic Communication Devices, Methods Of Forming Electrical Communication Devices, And Communications Methods|
|US20070290863 *||Aug 30, 2007||Dec 20, 2007||Tuttle John R||Radio Frequency Identification Device And Method|
|US20110174459 *||Jan 18, 2011||Jul 21, 2011||Water Gremlin Company||Mold assemblies including removable inserts and associated methods of use and manufacture|
|USRE35746 *||Jul 3, 1996||Mar 17, 1998||Micron Technology, Inc.||Battery package and method using flexible polymer films having a deposited layer of an inorganic material|
|USRE36843 *||Sep 26, 1996||Aug 29, 2000||Micron Technology, Inc.||Polymer-lithium batteries and improved methods for manufacturing batteries|
|U.S. Classification||249/134, 164/138|
|International Classification||H01M4/84, B22C3/00, B22D25/04|
|Cooperative Classification||H01M4/84, B22C3/00, B22D25/04, Y02E60/12|
|European Classification||H01M4/84, B22D25/04, B22C3/00|