Communications: electrical – Condition responsive indicating system – Specific condition
Patent
1982-12-10
1985-12-10
Myracle, Jerry W.
Communications: electrical
Condition responsive indicating system
Specific condition
73660, G08B 2100
Patent
active
045583110
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a method and an apparatus for monitoring the tool status in a tool machine with cyclic cutting machining, for instance a milling machine.
Within the machining industry there has been a demand for monitoring the status of the tools in continuously operating tool machines or machine tools. This monitoring shall especially include tool wear and failure. The demand for such monitoring has recently increased as the tool machines have become smaller and lighter, which has led to increased stresses on the machines. Since the power and speed also has increased the time margins for failures that previously existed have decreased. The problems are common for all cyclically operating tool machines.
The object of the present invention is to remove or reduce the problems mentioned above in connection with tool machines. Thus, the object of the invention is a method and an apparatus for monitoring the condition of the tools in cyclically operating tool machines.
Of special importance is that the method in accordance with the present invention can be applied to already installed tool machines without a radical redesign of these machines.
The objects mentioned above are arrived at with a method and an apparatus in accordance with the attached patent claims.
The invention will be described in detail under reference to the attached drawings, on which:
FIG. 1 is a schematic view of a work spindle of a turning machine or lathe;
FIG. 2 is an idealized picture of the electrical measuring signal of a vibration sensor under normal operation;
FIG. 3 is an idealized picture of the measuring signal of the vibration sensor in the case of a defective tool;
FIG. 4 is a block diagram illustrating the basic principle of the present invention;
FIG. 5 is a block diagram of another embodiment of the present invention; and
FIG. 6 shows the basic principle for a computerization of the monitoring system.
FIG. 1 is a schematic view of a tool spindle 1 in for instance a milling machine (not shown). This tool spindle 1 can comprise a number of tools or cutting edges 2, in this case four cutting edges 2. It is appreciated that the number of cutting edges can vary from machine to machine and depends on work piece and process, however, for reasons of simplicity a milling machine with four cutting edges 2 will be described below. The spindle 1 rotates with speed f in the direction indicated by the arrow in FIG. 1. Thereby the cutting edges 2 will engage the work piece in succession one after the other. Thus, in this case the machining cycle comprises a one turn rotation of spindle 1. During this turn each of the four cutting edges 2 will cut the same amount of material from the work piece.
Under normal operation, that is when the cutting edges are essentially identical, properly centered and not worn out, each of the four cutting edges 2 will cut the same amount of material from the work piece. This is the ideal situation that should be aimed at. However, if one of the cutting edges 2 should be defective (worn out, tool failure) this will result in unbalance and an improper machining of the work piece. Since the defective cutting edge 2 will now cut less material than a faultless cutting edge, the following cutting edge 2 will be more heavily loaded than normal, since it now on top of its normal cutting amount also has to cut the amount of material that the defective cutting edge has left.
The above difference between normal operation and operation with defective cutting edge results in differences in vibration and impulse. These differences are, in accordance with the present invention, utilized for detecting defective cutting edges. However, a great problem has been the fact that the vibrations that result from the engagement of the tools with the work piece to a high extent disguised by other vibrations that the machine generates under normal operation and are distorted by the transmission through different machine parts between the tool or work piece and the accelerometer. Thus, the problem that is solved by the p
REFERENCES:
patent: 2915897 (1959-12-01), Hoffmann
patent: 3277695 (1966-10-01), Joline
patent: 3400578 (1968-09-01), Frarey et al.
patent: 4063450 (1977-12-01), Lyons
patent: 4087801 (1978-05-01), Noh
patent: 4352293 (1982-10-01), Kurihara et al.
Eriksson Hans
Forsgren Roland
Garpendahl Gunnar
Wallentin Bengt
KB WIBRA
Myracle Jerry W.
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