CHAPTER XXXII. SLOTTING MACHINES.

Slotting machines with vertical¹ cutting movement differ from planing machines in several respects, to which attention may be directed. In slotting, the tools are in most cases held rigidly² and do not swing from a pivot³ as in planing machines. The tools are held rigidly for two reasons; because the force of gravity cannot be employed to hold them in position at starting, and because the thrust or strain of cutting falls parallel, and not transverse to the tools as in planing. Another difference between slotting and planing is that the cutting movement is performed by the tools and not by movement of the material. The cutting strains are also different, falling at right angles to the face of the table, in the same direction as the force of gravity, and not parallel to the face of the table, as in planing and [135] shaping machines.

The feed motion in slotting machines, because of the tools being held rigidly, has to operate differently from that of planing machines. The cross-feed of a planing machine may act during the return stroke, but in slotting machines, the feed movement should take place at the end of the up-stroke, or after the tools are clear of the material; so much of the stroke as is made during the feeding action is therefore lost; and because of this, mechanism⁴ for operating the feed usually has a quick abrupt⁵ action so as to save useless movement of the cutter bar.

The relation between the feeding and cutting motion of reciprocating⁶ machines is not generally considered, and forms an interesting problem for investigation⁷.

(1.) Name some of the differences between planing and slotting machines.—(2.) Why should the feed motion of a slotting machine act abruptly⁸?—(3.) To what class of work are slotting machines especially adapted?

1 vertical   

adj.垂直的，顶点的，纵向的；n.垂直物，垂直的位置

参考例句：

• The northern side of the mountain is almost vertical.这座山的北坡几乎是垂直的。
• Vertical air motions are not measured by this system.垂直气流的运动不用这种系统来测量。

2 rigidly   

adv.刻板地，僵化地

参考例句：

• Life today is rigidly compartmentalized into work and leisure. 当今的生活被严格划分为工作和休闲两部分。
• The curriculum is rigidly prescribed from an early age. 自儿童时起即已开始有严格的课程设置。

3 pivot   

v.在枢轴上转动；装枢轴，枢轴；adj.枢轴的

参考例句：

• She is the central pivot of creation and represents the feminine aspect in all things.她是创造的中心枢轴，表现出万物的女性面貌。
• If a spring is present,the hand wheel will pivot on the spring.如果有弹簧，手轮的枢轴会装在弹簧上。

4 mechanism   

n.机械装置；机构，结构

参考例句：

• The bones and muscles are parts of the mechanism of the body.骨骼和肌肉是人体的组成部件。
• The mechanism of the machine is very complicated.这台机器的结构是非常复杂的。

5 abrupt   

adj.突然的，意外的；唐突的，鲁莽的

参考例句：

• The river takes an abrupt bend to the west.这河突然向西转弯。
• His abrupt reply hurt our feelings.他粗鲁的回答伤了我们的感情。

6 reciprocating   

adj.往复的；来回的；交替的；摆动的v.报答，酬答( reciprocate的现在分词 )；（机器的部件）直线往复运动

参考例句：

• Dynamic loading is produced by seismic forces, non-steady wind, blast, reciprocating machinery. 动荷载是由于地震力、不稳定的风、冲击波，往复式机器所产生。 来自辞典例句
• The prime mover may be a gas reciprocating engine. 原动机可能是燃气往复式发动机。 来自辞典例句

7 investigation   

n.调查，调查研究

参考例句：

• In an investigation,a new fact became known, which told against him.在调查中新发现了一件对他不利的事实。
• He drew the conclusion by building on his own investigation.他根据自己的调查研究作出结论。

8 abruptly   

adv.突然地，出其不意地

参考例句：

• He gestured abruptly for Virginia to get in the car.他粗鲁地示意弗吉尼亚上车。
• I was abruptly notified that a half-hour speech was expected of me.我突然被通知要讲半个小时的话。