| 摘要 |
Material for prodn. of moulds for casting metal comprises a mixture of sand, binder and at least two catalysts, one of which is fast acting and the other slow acting. The rate at which the sand or binder is supplied to the mixer, and the temp. of the sand, are continuously monitored and the rate of addn. of the catalysts and their relative proportions, are automatically controlled in response to those parameters to produce a predetermined hardening time. Pref. the ambient temp. is also monitored and used to determine the temp. in the mixing chamber. Thus parameter is input into the catalyst mix control system. That system may be provided with a memory in which are stored sets of data relating hardening time to temp. for a range of mixtures contg. the first catalyst, and similarly for mixtures contg. the second catalyst.
|
