Turret Punch Press Research Articles

A General Framework for Sustainability Assessment of Sheet Metalworking Processes

The sheet metalworking industries possess minimal knowledge in the area of sustainability despite having served as sub-contractors to various industrial sectors. This also highlights that suitable indicators for measuring the sustainability performance of sheet metalworking operations are poorly addressed. As sustainability assessment is regarded as a vital part of sustainable development, this paper has been aimed at establishing a general framework for sustainability assessment of sheet metalworking processes. The main attention was paid to two important processes—the cutting operations with a CNC turret punch press machine and sheet metal bending operations with CNC press brake machine. Stepwise guidelines to implement the proposed framework in sheet metalworking industries are consequently presented. Besides, this study contributes to developing an applicable sustainability indicator set for assessing such manufacturing processes. It makes a valuable contribution to advancing the narrow body of knowledge on the under-researched scope.

Networked Remote Monitoring System for NC Turret Punch Press

With the rapid development of the modern technology, 3G network technology has become increasingly widespread. Using the high speed transmission characteristics of 3G network technology, the system components of a remote monitoring system based on 3G for NC turret punch press (NCT) is proposed, which solve slow transmission rate, narrow bandwidth besides faults of other network used in NCT. Based on the analysis of the 3G network technology application in the remote monitoring, the application architecture of the remote monitoring system is presented that suits for NCT, and a complete design plan of hardware and software is provided to achieve 3G technology applying to remote monitoring of NCT. A reference to network management and maintenance for manufacturing equipments is given.

Method of Holes Machining Path Optimization for NC Turret Punch Press

The basic composition and working principle of the turret punch press were analyzed, the recent distance method and genetic algorithm optimize method of holes machining path of NC turret punch press was put forward, the corresponding mathematical model and optimization algorithm was respectively given, these two kinds of optimization methods aiming at different types of holes are compared with the examples, put forward a kind of the integrated holes machining path optimization.

Optimal design of a main driving mechanism for servo punch press based on performance atlases

The servomotor drive turret punch press is attracting more attentions and being developed more intensively due to the advantages of high speed, high accuracy, high flexibility, high productivity, low noise, cleaning and energy saving. To effectively improve the performance and lower the cost, it is necessary to develop new mechanisms and establish corresponding optimal design method with uniform performance indices. A new patented main driving mechanism and a new optimal design method are proposed. In the optimal design, the performance indices, i.e., the local motion/force transmission indices ITI, OTI, good transmission workspace good transmission workspace(GTW) and the global transmission indices GTIs are defined. The non-dimensional normalization method is used to get all feasible solutions in dimensional synthesis. Thereafter, the performance atlases, which can present all possible design solutions, are depicted. As a result, the feasible solution of the mechanism with good motion/force transmission performance is obtained. And the solution can be flexibly adjusted by designer according to the practical design requirements. The proposed mechanism is original, and the presented design method provides a feasible solution to the optimal design of the main driving mechanism for servo punch press.

114 ウェーブレッド変換を用いたタレットパンチプレスの状態モニタリング(セッション4 機械の状態監視)

Immediate detection of abnormalities which occur in a production machine and taking a prompt and appropriate action are essential to maintain. Repair is required before the defective product is made in an actual production plants. This study aims to develop a condition monitoring methodology for a punching machine based on wavelet analysis of the impulsive acceleration response during the punching process. The acceleration response on the die in a turret punch press was measured during a repetitive punching test and analyzed with wavelets whose mother wavelet was the third derivative of the Gaussian function. The signal concentration measure evaluated from the extrema of the wavelet transform showed a considerable correlation with the wear transition, thus, it was suggested that it could be a signature of the tool wear progress and useful as a potential measure for the tool wear monitoring.

Evaluation of the Dependence of Tensile Strength and Fracture Strain of PLA Film on Machining Method

Some machining methods were used for making prototype of biodegradable stent made from poly lactic acid(PLA) film. Decrease of the tensile strength and fracture strain after machining was frequently observed. Therefore, in this paper, the tensile strengths of the films after machining were evaluated. The tensile strengths had maximum average value of 127.2MPa by the cutting plotter, and the minimum average value of 89.4MPa by the excimer laser. The machined surfaces were observed by scanning electron microscope. The machined surfaces by the cutting plotter and FHG -YAG laser were relative smooth. Those by the excimer laser and oxygen RIE, however, were rough. That by turret punch press was relative smooth and had flake-like burr. The surface roughness was related to the tensile strength, but not always related to fracture strain. It is supposed that surface irregularity caused the stress concentration and it reduced the tensile strength. On the other hand, it is supposed that the fracture strain was affected by the changes of property of surface and inner material, and they was caused by the shear deformation and the resolidification, crystallization and degradation induced by the processing heat.

A New Type of Servo Direct Drive Turret Punch Press

A new type of servo direct drive turret punch press is presented. A servomotor to drive the eccentric-toggle mechanism is used in our design, which combines the advantages of mechanical and hydraulic turret punch press. The displacement, velocity, and acceleration of the punch are calculated, through the kinematics analysis. So, the motion of the punch is controllable through the rotation of the servomotor. Then, the inverse kinematics analysis is studied in detail, and the corresponding motion of the servomotor can be gotten, for different punch motion curves, according to the production requirement. For example, when we design a motion of the punch for a particular stamping process, the motion of servomotor can be obtained through the inverse kinematics analysis. Finally, Output force is acquired by static force analysis, which decides the working capability of the mechanism.

The behaviour of a modern cell structure subjected to compressive load

A novel manufacturing process of lightweight cell structures is based on laser cutting and punch pressing techniques. The process based on turret punch press with laser is flexible and, therefore, the cell structure is easy to tailor. The punch press process enables even the cost effective one-off production. The new kind cell structure is considerably simpler than conventional ones. The studied cell structure consists of two plates. Both plates are manufactured using punch pressing and laser cutting. Truncated cones are formed with forming tools of a turret punch press. The flat shape of truncated cone is essential for joining the plates together. Joining methods to be used depend on the nature of the loads and other requirements. This manufacturing method gives an opportunity to tailor the cell structure. For example, the rigidity of the cell structure can be altered by changing the number and location of the embosses. Furthermore, the shape of the embosses can be varied, as well as their height, width and length. This feature makes it possible to manufacture even tapered cells in thickness direction. Formed cell structures are rather new constructions. Therefore, these kinds of structures need studying. The aim of this work is to study the behaviour of a cell structure subjected to compressive load. Main results of the study will be presented in this paper.

101 せん断・鍛造を主体とする複合微細成形加工(OS 材料の超精密加工とマイクロ加工)

In this paper, we describe a die-forming machine for fabricating three-dimensional microcomponents. This is based on the turret punch press, and material processing operations such as rotation of material and other functions are incorporated. The results of practical forming experiments that the developed micropress reliable for fabricating micro components.

Optimization of the nibbling operation on an NC turret punch press

The fabrication of sheet metal parts on an NC turret punch press is accomplished by first punching the desired holes in the parts nested on the sheet stock followed by nibbling the boundaries of the parts in order to separate them from the sheet. This paper addresses the problem of minimization of the total time taken for the nibbling operation for a given sheet configuration of nested parts. Finding a solution to this problem requires the solution of two coupled sub-problems, namely the part sequence determination problem and the pierce point determination problem. In this paper, we present two approaches to optimizing the nibbling operation and discuss their performance on sample data sets. The incorporation of the proposed optimization scheme within CAD/CAM systems will lead to reduced processing times and more effective utilization of NC turret punch presses.

Estimation of Sound Pressure Level in C-Frame Turret Punch Press Using a Scale Model.

A method for estimation of the noise level of a C-frame turret punch press is proposed using the results of its scale model. Scale models are often used in the experimental analysis of noise since their structural design can be easily varied. However, the waveform of a punching force is more complex than that of an impulsive force from an impulse hammer, and the supporting exeiting conditions of the scale model are different from those of the actual machine. It is, therefore, difficult to directly apply the similarity law to the experimental results obtained using a scale model. In this study, various waveforms of punching force reported previously have been analyzed in the frequency domain and a method for simulation of the punching force using an impulse hammer has been investigated. The difference between the supporting and exciting conditions of the actual machine and those of its scale model has been analyzed by a finite element method. It is found that two kinds of impulse hammers are necessary for the simulation of the punching force, and that the volumetric acceleration of the scale model is necessary for the estimation of the sound pressure level of the actual machine.

Vibration and Noise Reduction of C-Frame Turret Punch Press by Applying Turret as Impact Mass Damper.

We applied a set of turrets, which are used for providing punches and dies, to a damper for a C-frame turret punch press to reduce the vibration and noise. The upper-and lower-turret dampers have same characteristics as an impact mass damper. The damping characteristics can be changed by adjusting the preload. Those can effectively reduce the noise and the vibration although the contact area between the damper and the frame is small. In a wide frequency range, the effect of the sound pressure level reduction is the same for either one turret or a set of trurrets. In the lower frequency range, however, the set of the turret dampers can reduce the sound pressure level more effectively than one turret damper. As a result, the amplitude of the first tuning vibration, which is a natural vibration mode of C-type structures, is reduced up to 1/9 of the original structure, and the reduction in the sound pressure level is over 6dB. Furthermore, the complex structure of the turret damper and the double wall eliminates the first tuning vibration, and is estimated to reduce the sound pressure level in the actual punching by about 11dB.

Determination of turret configuration and hit sequence for optimization of NC turret punch press operation

Abstract This paper addresses the problem of minimization of the time taken to process sheet metal stock on an NC turret punch press. The processing lime of a sheet depends primarily on (1) the sequence in which the hits are made and )2) the arrangement of tools in the turret. Minimization of the processing time for a sheet requires the simultaneous solution of these two coupled sub-problems. Motivated by this view, the paper proposes three heuristics to find a hit sequence and a turret configuration that together minimize the processing time for a sheet. A comparison of the performance of these heuristics is provided. In addition, the paper examines some issues not considered in prior research but essential to the accurate modelling of the operation of an NC turret punch press, and discusses their incorporation in the proposed heuristics.

Large Capacity and High Speed Two-stage Hydraulic Servo Valve with a High Response Linear DC Motor and Its Application.

The authors have been developing a high speed hydraulic servo valve (Linear Servo Valve, LSV), which has a dynamic response of a 90° phase lag at 500Hz and the rated flow of 40L/min, with a high response linear DC motor to improve the accuracy and the productivity of sheet metal machines. This paper describes a large capacity and high speed two-stage LSV used the LSV as a pilot valve and its application to a hydraulic turret punch press. The following points are obtained:(1) The two-stage LSV exhibits a dynamic response of a 90° phase lag at 100Hz. It is clarified that the dynamic response of the two-stage LSV is 25% higher than that of the conventional three-stage hydraulic valves.(2) High ram speed of the hydraulic turret punch press, 2times higher than that of the conventional machine using the three-stage hydraulic servo valve, has been realized by adopting the two-stage LSV.(3) The hydraulic turret punch press using the two-stage LSV is able to reduce the power consumption to 91% in comparison with the conventional machine using the three-stage hydraulic servo valve.

Automatic Tool Selection for NC Turret Operation in Sheet Metal Stamping

In sheet metal fabrication using an NCT (numerically controlled turret punch press) machine, automatic tool selection is a major problem to be solved to improve its production performance. However, this operation has been done either manually or semi-automatically by human experts. In this paper, we have introduced the shape-index-set to handle the shape of sheet metal parts and developed an algorithm through which one can find the successive matching curves between two curve lists, one from the punching tool and the other from the boundaries of the sheet metal part. The algorithm is used to select the tools automatically to punch out the boundaries of sheet metal parts. Several experiments are presented to prove the successful tool selection.

Noise Reduction of Turret Punch Press with C-Frame. (2nd Report, Identification of Noise Source by Means of Acoustic Modal Analysis).

In this study, noise sources in a C-frame turret punch press are experimentally analyzed using a scale model. The distribution of sound pressure levels around the C-frame is measured in order to clarify the portion mainly generating the noise. As a result, the sound pressure level is found to become maximum at the open side of the C-frame, in which a punch-die set is usually installed. The result is the same as in previous former research work. However, the noise sources cannot be identified from such distribution. Thus, the sound field, which includes information of both amplitude and phase of sound vibration, is analyzed on planes parallel and perpendicular to the side panel of the C-frame by a modal technique. From the experimental results, it is found that the membranous vibration of the side panel, as well as the first specific vibration mode of the C-frame, must be damped for noise reduction.

Noise Reduction of Turret Punch Press with C Frame.

Noise Reduction of Turret Punch Press with C Frame.

Evaluation for Vibration Restriction of Punch Press by CAE.

A computerized numerically controlled C-frame turret punch press for sheet metal punching induces impulsive vibration and accompanying noise when punching. Actual study of the vibration and noise reduction has been mainly carried out by experimental analysis using actual machine structures. In recent years, the finite element method (FEM) has spurred remarkable progress in numerical analysis. In the analysis of actual complicated structures by the FEM, many natural frequencies and eigenvectors are obtained in the specified frequency range as a result of computer calculations. Important modes for the vibration restriction are usually picked out from the results of FEM analysis by professional engineers on the basis of experimental results. In this study, bending vibration of a C-frame turret punch press frame which radiates noise when punching was noticed. Then, a new evaluation criterion of the vibration which strongly influenced noise radiation, that is, "modal inertance between the load point and the response area", was developed. Examination of the modal inertance in comparison with the experimental results showed effectiveness in actual use. Furthermore, this evaluation criterion was applied to improve the actual frame structure of the C-frame turret punch press to acquire a much more restricted "vibration-free" structure and confirmed the criterion's effectiveness.

A Supporting System for Making NC Programs by Way of Knowledge Engineering Approach

Conventionally a processing program for NC (numerical control) machine is coded by a skilled operator or programmer, who has the excellent experience of machine work. As compared with the processing time taken by NC machine, the programming time is extremely long even the skilled programmer does it. According to our supporting system, a processing program is automatically generated from the output of CAD (computer aided design) system. The prototype of our supporting system is applied to the NC turret punch press machine, wherein the shape, size of the holes to be punched out and the order of the processings are indicated by the program. Usually the skilled programmer knows which tools installed in the turret of the machine should be used and how the order of the processings should be determined. The present system contains such information in the knowledgebase and uses it to generate the processing program. The knowledge in the knowledgebase consists of two kinds of the informations. The prototype system developed generates a processing program much faster than a skilled programmer. The result shows that the practical model can be developed by increasing the amount of knowledges.

An Algorithm for NC Turret Punch Press Tool Location and Hit Sequencing

Abstract This article proposes a new heuristic algorithm for minimizing part programs for numerical control (NC) punch presses. The part program contains the order in which the holes are punched into the part and the assignments of the tools to the indexing turret. The problem is broken down into two classical subproblems: the traveling salesman problem (TSP) and the quadratic assignment problem (QAP). By generating a feasible solution and then alternately improving the subproblems, good solutions are obtained in reasonable time. The algorithm is described, and then empirical results are given for applying the algorithm to real and randomly generated problems.