共查询到20条相似文献,搜索用时 0 毫秒
1.
2.
A universal velocity profile generation approach for high-speed machining of small line segments with look-ahead 总被引:2,自引:2,他引:0
Fu-Yuan Luo Yun-Fei Zhou Juan Yin 《The International Journal of Advanced Manufacturing Technology》2007,35(5-6):505-518
Usually a complex contour-machining program generated by CAD/CAM systems composes a lot of small line segments. The intelligence
of look-ahead is key to meeting the demand of high speed and high accuracy in the machining of these line segments. By now
most researchers just utilize the simplest trapezoidal velocity profiles to deal with the look-ahead problem. Also the number
of look-ahead line segments in most commercially available CNC systems is fixed, which cannot make full use of CNC processors.
Therefore, a universal velocity profiles generation approach and corresponding optimal look-ahead algorithm based on dynamic
back tracking along a doubly linked list are proposed in this paper. Two novel strategies, one for reducing feed rates fluctuation
and the other for reducing move errors that come from digital integration and accumulated computation, are also presented.
By using the proposed look-ahead techniques, arbitrary velocity profiles having the desired acceleration and deceleration
characteristics for the movement of a lot of small line segments can be generated efficiently. Thus, the machining productivity
can be dramatically increased without sacrifice of accuracy. The results of simulations and experiments showed the proposed
approach was feasible and effective. 相似文献
3.
三次多项式型微段高速加工速度规划算法研究 总被引:3,自引:1,他引:3
为满足高速数控加工的要求,提出了一种三次多项式加减速控制模型.该模型能保证高速运行过程中加速度的连续,使机床运行平稳,避免产生大的冲击.针对连续微段的高速加工,建立了满足最大速度、最大加速度、几何运动轨迹及长度约束条件下的轨迹速度规划策略,并给出三次多项式型速度规划算法的实现流程图.试验结果表明,该算法能实现连续微段间进给速度的高速衔接,大大缩短加工时间并提高加工效率.该算法已成功应用于多坐标数控高速微细加工系统中. 相似文献
4.
5.
Development of a real-time look-ahead interpolation methodology with spline-fitting technique for high-speed machining 总被引:1,自引:1,他引:0
Meng-Shiun Tsai Hao-Wei Nien Hong-Tzong Yau 《The International Journal of Advanced Manufacturing Technology》2010,47(5-8):621-638
Methodologies for converting short line segments into parametric curves were proposed in the past. However, most of the algorithms only consider the position continuity at the junctions of parametric curves. The discontinuity of the slope and curvature at the junctions of the parametric curve might cause feedrate fluctuation and velocity discontinuous. This paper proposes a look-ahead interpolation scheme for short line segments. The proposed interpolation method consists of two modules: spline-fitting and acceleration/deceleration (acc/dec) feedrate-planning modules. The spline-fitting module first looks ahead several short line segments and converts them into parametric curves. The continuities of the slope and curvature at each junctions of the spline curve are ensured. Then the acc/dec feedrate-planning module proposes a new algorithm to determine the feedrate at the junction of the fitting curve and unfitted short segments, and the corner feedrate within the fitting curve. The chord error and acceleration of the trajectory are bounded with the proposed algorithm. Simulations are performed to validate the tracking and contour accuracies of the proposed method. The computational efforts between the proposed algorithm and the non-uniform rational B-spline (NURBS)-fitting technique are compared to demonstrate the efficiency of the proposed method. Finally, experiments on a PC-based control system are conducted to demonstrate that the proposed interpolation method can achieve better accuracy and reduce machining time as compared to the approximation optimal feedrate interpolation algorithm. 相似文献
6.
针对复杂曲面在采用连续微段模式加工的过程中合成速度波动大导致加工效率降低的问题,提出了适用于微段加工的样条曲线重构新算法,该方法包含建立一种具有快速递推性质的样条曲线,及基于该曲线的速度规划和快速递推插补加工的方法。实验表明,算法在保证加速度连续的条件下,通过样条重构及速度规划减少了频繁加减速,提高了加工效率;快速递推则提高了插补计算的速度,插补点精确通过微段节点,保证了加工精度,提升了数控系统的性能。 相似文献
7.
An optimal feedrate model and solution algorithm for a high-speed machine of small line blocks with look-ahead 总被引:6,自引:3,他引:3
Jun Hu Lingjian Xiao Yuhan Wang Zuyu Wu 《The International Journal of Advanced Manufacturing Technology》2006,28(9):930-935
In complex high-speed machining of consecutive small line blocks, the tool path segments can be so short that a machining
center moving at a high feedrate cannot accelerate or decelerate fast enough to make direction changes accurately. Aiming
at adjusting the feedrate automatically to achieve maximum productivity, this paper present a novel mathematical model considering
the key and representative factors, and then based on it, propose an algorithm to seek the approximate optimal feedrate by
evaluating the toolpath ahead. Simulation results demonstrate the machine using the proposed model and algorithm can go fast
where possible and to slow down just enough where needed and the productivity can be improved dramatically . 相似文献
8.
An optimal feedrate model and solution algorithm for a high-speed machine of small line blocks with look-ahead 总被引:1,自引:0,他引:1
Jun Hu Liangjian Xiao Yuhan Wang Zuyu Wu 《The International Journal of Advanced Manufacturing Technology》2006,28(9-10):930-935
In complex high-speed machining of consecutive small line blocks, the tool path segments can be so short that a machining center moving at a high feedrate cannot accelerate or decelerate fast enough to make direction changes accurately. Aiming at adjusting the feedrate automatically to achieve maximum productivity, this paper present a novel mathematical model considering the key and representative factors, and then based on it, propose an algorithm to seek the approximate optimal feedrate by evaluating the toolpath ahead. Simulation results demonstrate the machine using the proposed model and algorithm can go fast where possible and to slow down just enough where needed and the productivity can be improved dramatically. 相似文献
9.
10.
根据计算机数字控制系统的实际性能和非均匀有理B样条曲线的几何特性,设计了一种能够实现加速度平滑过渡的高效非均匀有理B样条曲线插补器。首先,该插补器利用快速插补计算模拟实际加工过程,找到加速度不连续的点;然后,采用S曲线加减速方法向后逆求减速点,并通过约束速度和加速度的方法,预估S曲线加减速第三阶段起点,不仅提高了所求减速点位置的精度,还实现了减速点处加速度的连续性。仿真结果表明,该插补器能在保证加工精度的前提下,以较高效率实现加速度的平滑过渡。 相似文献
11.
Generation of velocity profiles with speed limit of each axis for high-speed machining using look-ahead buffer 总被引:1,自引:0,他引:1
An efficient look-ahead algorithm to generate velocity profiles is presented in this paper. Algorithm allows for a nonzero
starting point velocity and end point velocity of every line segment to increase machining productivity. The paper considers
the intelligence of look-ahead to achieve faster machining speed, along with required accuracy. Speed limitation of a specific
axis and the direction change of an axis are newly added to the constraints of the velocity profile problem. This paper solves
graphically the problem of generating velocity profiles and derives the equations for representing the velocity profile. A
method to manage the look-ahead buffer is also proposed. To generate velocity profiles using the look-ahead buffer, three
phases are proposed. Phase 1 determines the velocity conditions such as the maximum velocity, starting point velocity and
end point velocity. In phase 2, velocity profiles are generated independently. Phase 3 handles the change of the start or
end point velocity. This phase 3 is repeated until all adjacent point velocities are the same. The proposed method was utilized
in the manufacturing field to engrave aluminum tire molds. It was demonstrated that this method contributes to an increase
of the machining accuracy and a reduction of the production time. 相似文献
12.
13.
为实现加工过程中进给速度和加速度的平滑过渡,减小其突变时对机床的冲击,更好地保证加工精度,提出一种基于S型加减速的前瞻自适应非均匀有理B样条曲线插补算法.该算法根据弓高误差的要求,确定出各插补点的自适应进给速度及位置参数,然后找出速度改变点及其等速区间.为避免相邻速度改变点间加减速过程的互相影响,分别在插补前瞻距离和预前瞻距离内,根据设备允许的最大加速度、加加速度以及S型加减速算法对各速度改变点参数进行分析,筛选出决定加减速过程的关键点,再进行S型加减速控制,使进给速度和加速度得以平滑过渡,从而满足机床加减速能力的要求.仿真结果表明,该算法能够满足高速高精度的要求,验证了其可行性. 相似文献
14.
15.
16.
17.
Comparative study of conventional and micro WEDM based on machining of meso/micro Sized Spur Gear 总被引:1,自引:0,他引:1
Mohammad Yeakub Ali A. N. Mustafizul Karim Erry Yulian T. Adesta Ahmad Faris Ismail ’Aisy Anuarin Abdullah Mohd Nazrol Idris 《International Journal of Precision Engineering and Manufacturing》2010,11(5):779-784
This paper discusses the comparison of micro machining process using conventional and micro wire electrical discharge machining
(WEDM) for fabrication of miniaturized components. Seventeen toothed miniaturized spur gear of 3.5 and 1.2 mm outside diameter
were fabricated by conventional and micro WEDM respectively. The process parameters for both conventional and micro WEDM were
optimized by preliminary experiments and analysis. The gears were investigated for the quality of surface finish and dimensional
accuracy which were used as the criteria for the process evaluation. An average surface roughness (Ra) of 50 nm and dimensional accuracy of 0.1–1 μm were achieved in micro WEDM. Whenever applied conventional WEDM for meso/micro
fabrication, a Ra surface roughness of 1.8 μm and dimensional accuracy of 2–3 μm were achieved. However, this level of surface roughness and
dimensional accuracy are acceptable in many applications of micro engineering. A window of conventional WEDM consisting of
low energy discharge parameters is identified for micromachining. 相似文献
18.
19.
The cutting heat dissipation in chips, workpiece, tool and surroundings during the high-speed machining of carbon steel is quantitatively investigated based on the calorimetric method. Water is used as the medium to absorb the cutting heat; a self-designed container suitable for the high-speed lathe is used to collect the chips, and two other containers are adopted to absorb the cutting heat dissipated in the workpiece and tool, respectively. The temperature variations of the water, chips, workpiece, tool and surroundings during the closed high-speed machining are then measured. Thus, the cutting heat dissipated in each component of the cutting system, total cutting heat and heat flux are calculated. Moreover, the power resulting from the main cutting force is obtained according to the measured cutting force and predetermined cutting speed. The accuracy of cutting heat measurement by the calorimetric method is finally evaluated by comparing the total cutting heat flux with the power resulting from the main cutting force. 相似文献
20.
The cutting heat dissipation in chips, workpiece, tool and surroundings during the high-speed machining of carbon steel is
quantitatively investigated based on the calorimetric method. Water is used as the medium to absorb the cutting heat; a self-designed
container suitable for the high-speed lathe is used to collect the chips, and two other containers are adopted to absorb the
cutting heat dissipated in the workpiece and tool, respectively. The temperature variations of the water, chips, workpiece,
tool and surroundings during the closed high-speed machining are then measured. Thus, the cutting heat dissipated in each
component of the cutting system, total cutting heat and heat flux are calculated. Moreover, the power resulting from the main
cutting force is obtained according to the measured cutting force and predetermined cutting speed. The accuracy of cutting
heat measurement by the calorimetric method is finally evaluated by comparing the total cutting heat flux with the power resulting
from the main cutting force.
__________
Translated from Journal of South China University of Technology (Natural Science Edition), 2006, 34(11): 1–4 [译自: 华南理工大学学报(自然科学版)] 相似文献