SOME ADVANTAGES CLAIMED FOR COUNTERBLOW FORGING HAMMERS

The results of investigations carried out by the DIGEP Diosgyor Machine Works, Hungary, into the relative performances of a counterblow hammer and a conventional drop hammer in terms of the proportions of energy used for work and energy lost per blow are discussed. The results indicate that the counterblow hammer has the advantage in every case, and in some instances is significantly superior. It is also shown that the point at which 'energy lost' exceeds 'energy used usefully' occurs earlier for a drop hammer than for a counterblow hammer. The equal and opposite force arrangement which is a feature of the counterblow hammer affords important advantages in a number of areas, many of which derive advantages from the fact that it represents a closed-circuit energy system. One of the most obvious benefits, obtained as a result of eliminating the massive fixed anvil required for a drop hammer, is a reduction in size and weight of the foundations. It is estimated, for example, that the foundation required for a counterblow hammer is somewhere between one-quarter and five-eighths of the volume of that for a drop hammer of comparable rating. Moreover, the foundation of a counterblow hammer is not called upon to accept (and therefore to transmit) the major impact and vibrations resulting from the blow. The 'fall-out' area of earth-transmitted vibrations is thus significantly smaller for a counterblow hammer. On such a machine, the lower ram is only some 5 to 10 percent heavier than the upper ram, whereas it is suggested that for a drop hammer the weight of anvil required may be as much as 20 to 25 times greater than that of the moving ram.