High speed machining with internet monitoring.

Baltes, Liana ; Tierean, Mircea ; Eftimie, Lucian 等

1. INTRODUCTION

High speed machining among the intensive removing of metal means also the integral using of machining time to increase the productivity. To solve this problem it was realised an Internet application for the monitoring of the machining process. The presented solution refers to a combination of techniques designed to decrease production costs while shortening the work time through a set of combined solutions.

2. CHOOSING OF THE TOOL

The choosing of the tool according the type of application, in any cutting tool process, is crucial in obtaining of the good results. In this paper we propose to realise an high speed milling, remote controlled by the operator for a piece of hardened Duralumin 6061 T651 used in a polyurethane injection mould, by casting technology Reaction Injection Moulding. The piece is presented in figure 1.

The chosen tool (fig. 2) is a milling head, similar to "bull nose" mill, having inserts with high productivity geometry, which ensures high speed for the metal removing. There are assured such high operating conditions, as in table 1.

[FIGURE 1 OMITTED]

[FIGURE 2 OMITTED]

For the roughing milling, it was used an high degree of tool coverage, with adjustment of cutting speeds depending on the tool path and differentially feeding rate on tooth insertion into material. As result, a big volume of removed material approximate 38 [dm.sup.3], can be processed in an hour. The equipment used for machining was a vertical processing centres HAAS.

3. OPTIMIZATION OF MILLING TOOL PATHS

Using of adequate software allows through attached routines the process optimisation, the most important being the computing of inactive positioning movement G0 and the choosing of the shortest paths of positioning and movements between milling areas. Shortness of cutting time is approximate 10-15% over the total process time. The software chosen for this application is ESPRIT CAM (fig. 3).

After compiling and optimizing of the milling tool paths (fig. 4), in order to prevent collisions and to find the stock that must be re-processed in previous operations, the simulation process was done (fig. 5).

[FIGURE 3 OMITTED]

[FIGURE 4 OMITTED]

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The final result is post-processed and is estimated the working time for the production planning. The estimation process is extremely important in planning and organizing of the technological production flow (fig.6).

4. REMOTE MANUFACTURING

Increasing of the processing cost, especially due of working time, can be reduced using the third measure, among the proper tool choosing and path optimisation, the remote controlling of the machine. This measure can be applied for "non-hazardous" processes considering the process precision, but big time consumers, as roughing and semi finishing processes (Cilliers, 2002).

It was developed a software application, compatible as data transfer and monitoring system with HAAS VF5 processors, which allows on-line working with the equipment, using the Internet and/or GSM link.

Such systems have been developed only on high-cost CNC equipments, but which, by their amortization extremely high (prices of equipment is 50-100% higher) rise the processing time cost, thus increasing of the product cost. The on-line system allows the loading of some programs much bigger than the equipments memory, thus assuring a long operating time without stopping. All these stops cause additional costs.

[FIGURE 6 OMITTED]

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In the tools' storehouse are introduced the adequate tools for roughing cut and semi finishing, that can be reached without the presence of operator. Being a more critical operation, the finishing phase requires the operator assistance.

For each equipment the monitoring is done in real time and it is possible to connect several equipment to a single PC (fig.7) (Kao et al., 1996).

The system warns through SMS message (mobile phone) only in the event of an accidental problem and betimes announces the stop of the machining process.

In this way it is possible to ensure the simultaneous working of several processing centres with a single operator or use the whole weekend's period. The small resources involved, as well as costs, make such an application to have extremely low monitoring prices and practically required only one network and Internet access.

The application has proved extremely useful in the case of parts which consume a lot of time. Practically, the only minimal technical condition required is to remove efficiently the chips in the case of concave parts, using an efficient multi-liquid jet cooling systems cooling or air (Song et al., 2005).

Another utility is the processing of a series of parts, with moderate tolerance, at which the tools wearing is at the range of 0.05 mm.

5. CONCLUSION

By cumulating manufacturing strategies, choosing the cutting conditions, tools and monitoring, the delivery time for products decreased significantly by increasing the number of working hours per week in combination with the decrease of industrial time costs per hour by reducing the labour costs per unit of product.

6. REFERENCES

Cilliers, C. (2002) Remote monitoring and diagnosis for control of EDM parameters, PhD thesis, Rand Afrikaans University

Kao Y.C. & Lin G.C.I. (1996) CAD/CAM collaboration and remote machining, Computer-integrated manufacturing systems, vol. 9, no3, pag. 149-160

Song, I.H.; Park, J.M. & Chung, S.C (2005) Web based interference verification system for injection mold design, Computer-Aided Design and Applications, 3 (1-4), pag. 129-138

DP Technology Corp. ESPRIT CAD/CAM Software, Camarillo, CA

HAAS Automation Inc.; Programming and operation Manual VF-series, Oxnard, CA

Table 1. Milling process parameters

 [F.sub.z] [A.sub.p]
S [rot/min] F [mm/min] V [m/min] [mm] [mm]

 7000 12000 703.36 0.571 3