| 摘要 |
A hydraulically powered repetitive impact hammer has internal features for ensuring continued automatic repetitive operation under adverse conditions, and fluid cushioning of internal parts to prevent damage from abrupt metal-to-metal contact. The hammer head of the impact hammer has an internal poppet which automatically closes to enable the buildup of pressure in a compression chamber during reloading in preparation for the hammer head's next blow, and automatically opens to enable the pressure in the compression chamber to drive the hammer head to strike an impact tool. To prevent inadvertent stalling of the hammer during reloading if the impact tool is pressed forcibly into contact with the working face after striking a blow, the amplification ratio of the hammer head is made greater than the amplification ratio of the poppet. Fluid cushioning of the hammer head to prevent abrupt metal-to-metal contact with the frame of the hammer at the end of the driving stroke is provided by a temporary fluid restriction which operates only when the hammer head is near the end of its driving stroke. Fluid cushioning of the poppet to prevent abrupt contact with the hammer head is provided by mating fluid cushioning surfaces formed on the hammer head and poppet, respectively, for enclosing fluid in a confined space and metering the escape of fluid from the confined space as the poppet approaches one or the other extremity of its range of movement in the hammer head.
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