Patent GB-964727-A (GB)
Title: A method and machine for the removal of cores and surface debris from castings and the like
IPC: B24C9/00
Filed: 1961-12-28
Abstract: 964,727. Tumbling; blasting. BELL INTERCONTINENTAL CORPORATION. Dec. 28, 1961 [Jan. 26, 1961], No. 46392/61. Heading B3D. A method for the removal of cores and surface debris from castings comprises subjecting castings requiring to be cleaned to a tumbling operation to shake out the casting core material and other loose debris, conveying said debris to a separator having a debris discharge, then shot-blasting said castings with blast media projected from a shot-blasting unit whilst they are being tumbled to remove residual core material while delivering the spent shot and debris material to said separator, and finally surface-cleaning said castings by the same shot-blasting unit. A tumble blast unit includes a cradle-type tumbling conveyer 12, e.g. constructed as in Specification 947,965, and a shot-blasting unit 16, e.g. constructed as in Specification 821,869, to which blast media is supplied by a hopper and feed shoot 18 under the control of a valve 42. A conveyer 20 leads by elevator 22 and cross-conveyer 24 to a hopper and shoot unit 26 delivering to a separator 28, e.g. constructed as in Specification 903,831. The separator has a discharge spout 29 delivering into a take-away device 30 and a discharge shoot 32 leading by elevator 34 to crossconveyer 36 having a primary delivery into the hopper 18 and a by-pass delivery through conduit 38 and valve 40 to the cross conveyer 24. A batch of castings stripped from their moulds is loaded into the blast cabinet and tumbled for a predetermined time to cause the more easily displaced sand and core material to fall out of the castings. The shot-blasting unit 16 remains idle with the valve 42 closed during this phase, and the valve 40 is opened. The sand and debris falling into the conveyer 20 passes to the separator 28 for discharge through the outlet 29. Separator overload material is recycled through elevator 34, conduit 38 and cross-conveyer 24 to the separator, until the system is substantially cleared by discharge of all the waste material to the device 30. The shot-blasting unit 16 is then activated and the valve 42 opened, blast media from the hopper 18 feeding to the shot-blasting unit. This initial blast operation usually dislodges a relatively heavy surge of sand from the interior of the castings. When this phase is completed, the valve 42 is closed; contaminated blast media continues to recycle through the by-pass valve 40 until all sand and contaminants are removed from re-usable media. The valve 42 is now re-opened and the valve 40 closed. Blast media circulates through the separator and the shot-blasting unit, the separator functioning to discord from the system the worn out abrasive and fine debris resulting from the finish cleaning. When this phase is completed, the castings are preferably tumbled for an additional period to allow all sand and blast media to drain from the castings before they are unloaded. The sequential control of the process may be performed manually, automatically or semiautomatically. Specification 923,693 also is referred to.