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"5. Van Zuylen, senator.
Cutting, as a process in converting material, includes the force to propel cutting edges, means to guide and control their action, and mechanism to sustain and adjust the material acted upon. In cutting with hand tools, the operator performs the two functions of propelling and guiding the tools with his hands; but in what [58] is called power operations, machines are made to perform these functions. In nearly all processes machines have supplanted hand labour, and it may be noticed in the history and development of machine tools that much has been lost in too closely imitating hand operations when machines were first applied. To be profitable, machines must either employ more force, guide tools with more accuracy, or move them at greater speed, than is attainable by hand. Increased speed may, although more seldom, be an object in the employment of machinery, as well as the guidance of implements or increased force in propelling them. The hands of workmen are not only limited as to the power that may be exerted, and unable to guide tools with accuracy, but are also limited to a slow rate of movement, so that machines can be employed with great advantage in many operations where neither the force nor guidance of tools are wanting.Bruce caught his breath sharply. He had scarcely time to consider what it all meant when the light flared up again, and the fair woman returned with a kettle and basin and a tin of mustard.97大香蕉在线.新闻大香蕉在线 中字大香蕉在线 高中生大香蕉在线 高清在线大香蕉大香蕉在线 偷拍 大香蕉在线 自慰大香蕉在线0 大香蕉在线 百度 百度 百度大香蕉在线06 大香蕉在线1025大香蕉在线 台湾 大香蕉在线 99r
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