摘要
增加刀轴转速,提高进给速度是当今木材加工设备发展的方向之一。液压夹紧轴套是目前木材加工设备(如高速四面刨、双端铣等)上普遍采用的刀具装夹技术。由于具有极高的夹持回转精度、重复定位精度、优良的动平衡和阻尼减振性能,液压夹紧轴套能够适应极高的转速和进给速度,可以显著地提高加工精度、改善加工表面质量和延长刀具的耐用度,可应用于任意以回转方式切削的木材加工设备上,如板式家具的双端铣、CNC加工中心、多锯片圆锯机及高速四面刨等。
本文所研究的快速液压装夹系统具有施压卸载和快速装卸刀具两部分功能。施压卸载部分的结构为双腔体,利用液压介质使腔壁产生变形来分别对电机主轴和刀具进行定心夹紧作用;快速装卸刀具部分是利用气能和机械能对刀具进行装卸作用。
在研究的过程中形成了关于液压夹紧轴套开发的基础理论(包括摩擦联结、密封腔内施压原理与方法、材料弹性变形理论、密封腔体薄壁计算方法等),建立了液压夹紧轴套密封腔薄壁的力学计算模型,并运用计算机技术进行液压夹紧轴套液压夹紧部分的辅助设计(加压介质的压力、容量和油腔薄壁结构尺寸、应力应变及传递的扭矩等的设计计算),以及快速装卸刀具部分的结构设计与优化。
通过对试制产品进行油腔薄壁的变形及承载能力验证试验表明,进行液压夹紧装置研制的基础理论是成立的,轴套油腔薄壁的力学计算模型是合理的;对于本文设计的结构,只要将内外腔的加压螺柱分别旋转1圈以上,轴套产生的夹紧力就能满足铣刀的铣削力矩要求;系统的结构设计是可行的,但需改进柱塞部分的密封性;40#工业油可用作液压夹紧轴套的施压介质。
To increase rotary speed and feeding speed of cutting tools is a trend in the development of the wood machining equipment. Hydraulic clamping sleeve is now widely adopted in the advanced equipments in wood processing, such as high speed 4-side planer, 2-end miller and so on. Owing to its excellent griping precision of clamping and good performance of dynamic equilibrium and damping, hydraulic clamping sleeve, applied to the wood machines with high speed, can increase the machining precision markedly, improve the quality of the processing surface and prolong the duration of the cutting tools. For all the above-mentioned advantages, the device can be adopted in any wood processing equipment with rotary cutter shaft, such as 2-end millers for processing board furniture, CNC, multi-blade circular saw and 4-side planers.
The system developed in the paper has two main functions: one is hydraulic griping, and the other is assembling and unasssembling the tools quickly. To fulfill the first function, two cavities are introduced in the system, and the hydro-medium in the cavities can be pressed to cause the thin walls of the cavities to deform so as to clamp the motor shaft and the tools respectively. The second function is performed by gaseous energy and mechanical energy.
Basal theory on the hydraulic clamping sleeve, comprising friction joint theory, principle and method of pressurizing, calculating methods of the thin wall of the sealed cavity, are produced in this paper. The mechanics-calculating model of the sealed cavity in the hydraulic sleeve is also constructed.
In the course of the research, CAD technique is introduced in the designing of hydraulic griping part, including the calculating of the pressure and capacity of the hydro-medium, the structure and measure of the cavities, the analysis of the stress and strain of the cavities, and the calculating of fastening torque. CAD technique is also used in the structural devising and optimizing of the quick assembling and unassembling tools.
The paper experimented the basal theory on the hydraulic clamping sleeve by measuring the deformation of the thin wall of the cavities and fastening torque transferred via the contact surface of the hydraulic clamping sleeve.
Several conclusions can be drawn from the experiments: the basal theory on the hydraulic clamping sleeve is right; the structure of the system is feasible except that the sealing of the pressurizing column is to be improved; 40# industrial oil can be adapted as the hydro-medium in the hydraulic clamping sleeve. The clamping force, transferred by tightening the pressurizing screw above one full circle, can fulfill the driving torque needed by millers.
引文
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