【单选题】
限位开关在电路中起的作用是 ___
A. 行程控制
B. 过载保护
C. 欠压保护
D. 短路保护
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答案
A
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相关试题
【单选题】
数控机床的脉冲当量是指 ___
A. 每个脉冲信号使数控机床移动部件产生的位移量
B. 数控机床移动部件每分钟进给量
C. 数控机床移动部件每秒钟位移量
D. 数控机床移动部件每分钟位移量
【单选题】
电机通过联轴器直接与丝杠联接，通常是电机轴与丝杠之间采用锥环无键联接或高精度十字联轴器联接，从而使进给传动系统具有较高的 和传动刚度，并大大简化了机械结构 ___
A. 传动精度
B. 运行速度
C. 传动位置
D. 传动频率
【单选题】
C.液压系统压力 D.液压系统油温 11239.数控机床进给传动方式有以下几种形式 ___其中 适用于负载力矩大、需要放大伺服电机输出扭矩的场合 (A)
A. 电动机通过齿轮与丝杆连接
B. 电动机通过联轴器直接与丝杆连接
C. 电动机通过齿形带与丝杆连接
D. 直线电动机直接驱动
【单选题】
数控机床的检测反馈装置的作用是：将其准确测得的 数据迅速反馈给数控装置， 以便与加工程序给定的指令值进行比较和处理 ___
A. 角位移或直线位移
B. 直线位移
C. 角位移
D. 直线位移和角位移
【单选题】
C.半闭环控制 D.半开环控制 11244.在半闭环数控系统中，位置反馈量是 ___
A. 进给伺服电机的转角
B. 机床的工作台位移
C. 主轴电机转速
D. 主轴电机转角
【单选题】
下列 检测元件检测线位移 ___
A. 感应同步器
B. 光电盘
C. 旋转变压器
D. 脉冲编码器 11247.数控机床按工艺用途分类，有切削类、成形类和特种加工类等 (A)下列四种数控机床中，
【单选题】
CNC 系统一般可用几种方式得到工件加工程序，其中 MDI 是 ___
A. 利用键盘以手动方式输入程序
B. 从串行通讯接口接收程序
C. 利用磁盘机读入程序
D. 从网络通过 Modem 接收程序
【单选题】
请找出下列数控屏幕上菜单词汇的对应英文词汇 SPINDLE.EMERGENCY STOP 、FEED.、 COOLANT ___
A. 主轴、急停、进给、冷却液
B. 冷却液、主轴、急停、进给
C. 主轴、冷却液、急停、进给
D. 进给、主轴、冷却液、急停
【单选题】
关于数控系统的串口通讯，错误的说法是 ___
A. 如果数据传输不正常，可以通过拔下数据通讯线进行复位，然后再插上通讯线
B. 确认数控系统串口功能是否已开通
C. 确认上位机软件里的参数设置和数控系统里面的串口参数是否一样
D. 进行串口通讯前，首先检查传输线是否完好
【单选题】
在数控程序传输参数中，“9600E71”，分别代表 ___
A. 波特率、奇偶校验、数据位、停止位
B. 数据位、停止位、波特率、奇偶校验
C. 波特率、数据位、停止位、奇偶校验
D. 数据位、奇偶校验、波特率、停止位
【单选题】
执行程序终了之单节 M02，再执行程序之操作方法为 ___
A. 按启动按钮
B. 按紧急停止按钮，再按启动按钮
C. 按重置 RESET)按钮，再按启动按钮
D. 启动按钮连续按两次
【单选题】
程序编制中首件试切的作用是 ___
A. 检验程序单的正确性，并检查是否满足加工精度要求
B. 检验零件工艺方案的正确性
C. 检验零件图样的正确性
D. 检验数控程序的逻辑性
【单选题】
全闭环进给伺服系统的数控机床，其定位精度主要取决于 ___
A. 检测装置的精度
B. 伺服单元
C. 机床传动机构的精度
D. 控制系统 11276.数控机床进给系统减少摩擦阻力和动静摩擦之差，是为了提高数控机床进给系统的
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