区别
• 齿形形状：矩形花键的齿形为矩形，键齿两侧面是平行于通过轴线的径向平面的两个平面。渐开线花键的齿廓为渐开线。
• 定心方式：矩形花键一般采用小径定心，即外花键和内花键的小径为配合面。渐开线花键采用齿形定心，受载时齿上有径向力，能起自动定心作用，使各齿受力均匀。
• 承载能力：矩形花键多齿工作，承载能力较高，但齿根较浅，相比渐开线花键强度稍弱。渐开线花键齿根较厚，强度高，齿数多，承载能力更强，适用于传递较大的扭矩和较高的转速。
• 加工工艺：矩形花键加工工艺相对简单，可用拉削、磨削等方法，不过内花键对于不通孔加工较困难。渐开线花键加工工艺与齿轮相似，可采用滚齿、插齿等展成法加工，便于采用冷搓、冷打、冷挤等无切屑加工工艺，生产效率高、精度高。
• 应用场景：矩形花键定心精度高、导向性好、成本低，常用于一般机械传动，如汽车变速器输入轴花键。渐开线花键常用于载荷较大、定心精度要求高的连接，如汽车的半轴与轮毂之间的连接。
相同处
• 功能作用：都是机械传动中的连接结构，由轴上的外花键和轮毂等零件上的内花键组成，用于传递扭矩，保证轴和轮毂之间的同心度，使它们在旋转过程中保持良好的同轴关系。
• 结构特点：都是在圆柱表面上加工出多个键齿和键槽，通过键齿和键槽的配合实现连接和传动。
• 精度要求：在设计和制造时，对两者的尺寸精度、形位公差、表面粗糙度等都有较高要求，以保证连接的可靠性和传动效率。
• 应用领域：都广泛应用于机械工程领域，如汽车、机床、飞机等机器中，在需要传递扭矩和保证定心精度的部位发挥重要作用。
Difference
• Tooth shape: The tooth shape of rectangular spline is rectangular, and the two sides of the key teeth are two planes parallel to the radial plane passing through the axis. The tooth profile of involute spline is involute.
• Centering method: Rectangular spline generally adopts small diameter centering, that is, the small diameter of the external spline and the internal spline is the matching surface. Involute spline adopts tooth shape centering. When loaded, there is radial force on the teeth, which can play an automatic centering role and make the force on each tooth uniform.
• Load capacity: Rectangular spline has multiple teeth and higher load capacity, but the tooth root is shallow, and the strength is slightly weaker than that of involute spline. Involute spline has thicker tooth root, higher strength, more teeth, stronger load capacity, and is suitable for transmitting larger torque and higher speed.
• Processing technology: The processing technology of rectangular spline is relatively simple, and can be used by broaching, grinding and other methods, but it is more difficult to process internal spline for non-through holes. The processing technology of involute splines is similar to that of gears. They can be processed by hobbing, gear shaping and other development methods, which is convenient for cold rolling, cold beating, cold extrusion and other chipless processing technologies, with high production efficiency and high precision.
• Application scenarios: Rectangular splines have high centering accuracy, good guidance and low cost, and are often used in general mechanical transmissions, such as automobile transmission input shaft splines. Involute splines are often used for connections with large loads and high centering accuracy requirements, such as the connection between the half shaft and the wheel hub of an automobile.
Similarities
• Function: Both are connection structures in mechanical transmissions, consisting of external splines on the shaft and internal splines on parts such as the wheel hub, used to transmit torque, ensure the concentricity between the shaft and the wheel hub, and keep them in a good coaxial relationship during rotation.
• Structural features: Both are machined with multiple key teeth and keyways on the cylindrical surface, and the connection and transmission are achieved through the cooperation of key teeth and keyways.
• Precision requirements: During design and manufacturing, high requirements are placed on the dimensional accuracy, geometric tolerance, surface roughness, etc. of both to ensure the reliability of the connection and transmission efficiency.
• Application areas: They are widely used in the field of mechanical engineering, such as automobiles, machine tools, aircraft and other machines, and play an important role in parts that need to transmit torque and ensure centering accuracy.