渐开线花键的定心方式为齿形定心。受载时齿上有径向力，能起自动定心作用，有利于各齿受力均匀，强度高，寿命长。用于载荷较大，定心精度要求较高以及尺寸较大的联接，如航空发动机、燃气轮机、汽车等。压力角45°的花键多用于轻载、小直径和薄型零件的联接。
The involute spline is centering in the shape of the tooth. The tooth has radial force on the tooth, and it can play the role of automatic centering, which is beneficial to the uniform force of each tooth, high strength and long life. It is used for large load, high precision and large size connection, such as aero engine, gas turbine, automobile and so on. The spline with a pressure angle of 45 degrees is used for the connection of light, ***all diameter and thin parts.
胜过机用虎钳的柔性虎钳，在装夹中能有效防止工件的翻转、倾斜，克服了机用虎钳因配合间隙大导致工件受力不均、加工发颤等现象；解决了现有轻型、精密工件加工时装夹不可靠的问题。
Flexible than vice machine vise, the clamping can effectively prevent the workpiece turning and tilt, overcome the machine vise for clearance to workpiece uneven stress, etc. to solve the phenomenon of processing tremble; the existing light and precision workpiece clamping reliability of the fashion。
机用虎钳的结构及原理。机用虎钳是机械加工中常用的装夹机构，其结构如图1所示。其主要工作原理：转动方头带动丝杠，在螺母（通过紧固螺钉固定在虎钳体上）的作用下，做螺旋运动的丝杠带动与之联接的活动座沿丝杠轴线方向来回移动。
The structure and principle of machine vise. Machine vise is a common clamping mechani*** in mechanical processing. Its structure is shown in Figure 1. The main principle: rotation of the lead screw nut in the square, (fixed in the vise body through a fastening screw) under the action of moving spirally driven screw connected with the movable seat to move back and forth along the screw axis.
螺旋副的间隙大，旋转时费力，使用中稳定性差。机用虎钳开合行程大，螺旋副的运行长度较长，为保证能够快速装夹，（金属加工真不错）机用虎钳螺旋副的螺距较大。较大的螺距意味着较大的螺旋升角，转动单圈进给量较大，使用时较费力；较大的螺距需要更大的配合间隙来确保螺旋副的正常使用。
The clearance of the helix pair is large, the rotation is hard and the stability of the use is poor. The machine has large opening and closing stroke, and the operation length of the screw pair is longer. In order to ensure quick clamping, metal machining is good. Larger pitch means larger spiral angle, larger single turn feed and more laborious use. Larger pitch needs more fit clearance to ensure the normal use of screw pair.