Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23Q—DETAILS, COMPONENTS, OR ACCESSORIES FOR MACHINE TOOLS, e.g. ARRANGEMENTS FOR COPYING OR CONTROLLING; MACHINE TOOLS IN GENERAL CHARACTERISED BY THE CONSTRUCTION OF PARTICULAR DETAILS OR COMPONENTS; COMBINATIONS OR ASSOCIATIONS OF METAL-WORKING MACHINES, NOT DIRECTED TO A PARTICULAR RESULT
  • B23Q17/00—Arrangements for observing, indicating or measuring on machine tools
  • B23Q17/09—Arrangements for observing, indicating or measuring on machine tools for indicating or measuring cutting pressure or for determining cutting-tool condition, e.g. cutting ability, load on tool
  • B23Q17/0952—Arrangements for observing, indicating or measuring on machine tools for indicating or measuring cutting pressure or for determining cutting-tool condition, e.g. cutting ability, load on tool during machining
  • B23Q17/0957—Detection of tool breakage
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23B—TURNING; BORING
  • B23B49/00—Measuring or gauging equipment on boring machines for positioning or guiding the drill; Devices for indicating failure of drills during boring; Centering devices for holes to be bored
  • B23B49/001—Devices for detecting or indicating failure of drills
• • G—PHYSICS
  • G05—CONTROLLING; REGULATING
  • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
  • G05B19/00—Programme-control systems
  • G05B19/02—Programme-control systems electric
  • G05B19/18—Numerical control [NC], i.e. automatically operating machines, in particular machine tools, e.g. in a manufacturing environment, so as to execute positioning, movement or co-ordinated operations by means of programme data in numerical form
  • G05B19/406—Numerical control [NC], i.e. automatically operating machines, in particular machine tools, e.g. in a manufacturing environment, so as to execute positioning, movement or co-ordinated operations by means of programme data in numerical form characterised by monitoring or safety
  • G05B19/4065—Monitoring tool breakage, life or condition
• • G—PHYSICS
  • G05—CONTROLLING; REGULATING
  • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
  • G05B2219/00—Program-control systems
  • G05B2219/30—Nc systems
  • G05B2219/37—Measurements
  • G05B2219/37026—Adjust sensor radially
• • G—PHYSICS
  • G05—CONTROLLING; REGULATING
  • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
  • G05B2219/00—Program-control systems
  • G05B2219/30—Nc systems
  • G05B2219/37—Measurements
  • G05B2219/37233—Breakage, wear of rotating tool with multident saw, mill, drill
• • G—PHYSICS
  • G05—CONTROLLING; REGULATING
  • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
  • G05B2219/00—Program-control systems
  • G05B2219/30—Nc systems
  • G05B2219/37—Measurements
  • G05B2219/37234—Monitor tool before, after and during machining
• • G—PHYSICS
  • G05—CONTROLLING; REGULATING
  • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
  • G05B2219/00—Program-control systems
  • G05B2219/30—Nc systems
  • G05B2219/37—Measurements
  • G05B2219/37242—Tool signature, compare pattern with detected signal
• • G—PHYSICS
  • G05—CONTROLLING; REGULATING
  • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
  • G05B2219/00—Program-control systems
  • G05B2219/30—Nc systems
  • G05B2219/37—Measurements
  • G05B2219/37352—Frequency
• • G—PHYSICS
  • G05—CONTROLLING; REGULATING
  • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
  • G05B2219/00—Program-control systems
  • G05B2219/30—Nc systems
  • G05B2219/37—Measurements
  • G05B2219/37353—Amplitude
• • G—PHYSICS
  • G05—CONTROLLING; REGULATING
  • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
  • G05B2219/00—Program-control systems
  • G05B2219/30—Nc systems
  • G05B2219/37—Measurements
  • G05B2219/37493—Use of different frequency band pass filters to separate different signals
• • G—PHYSICS
  • G05—CONTROLLING; REGULATING
  • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
  • G05B2219/00—Program-control systems
  • G05B2219/30—Nc systems
  • G05B2219/37—Measurements
  • G05B2219/37544—Compare detected signal to several references to derive several control actions
• • G—PHYSICS
  • G05—CONTROLLING; REGULATING
  • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
  • G05B2219/00—Program-control systems
  • G05B2219/30—Nc systems
  • G05B2219/37—Measurements
  • G05B2219/37545—References to be compared vary with evolution of measured signals, auto-calibrate

Definitions

• the invention relates to a device for monitoring rotating tools and in particular twist drills.
• the drill contour is recorded with a distance sensor and the detected contour is evaluated to detect damage or breakage of the drill.
• Feutlinske proposed using a shadow sensor or an optical sensor working according to the tri-angulation principle to record the contour of a milling cutter and to draw conclusions about the state of the rotating tool from the contour measurement.
• an optically operating distance sensor will become unusable or at least inaccurate relatively quickly due to drilling chips, drilling fluid or the like.
• inductive or magnetic distance sensors whose measuring spot allows the drill contour to be recorded, i.e. whose measuring spot typically has a diameter of less than 1 mm, fail in the harsh environmental conditions of an industrial multi-spindle drilling system.
• the invention is based on the object of specifying a device for monitoring rotating tools and in particular twist drills with which, for example on a multi-spindle drilling system, damage to the tool which necessitates replacement can be reliably detected.
• the distance sensor is designed such that the area which the distance sensor detects or scans is large compared to typical changes in the shape of the tool.
• a measuring spot of the level sensor with a diameter of approx. 4 mm is used.
• Such a distance sensor does not provide a signal which is directly related to the contour of the tool, since the measuring spot detects areas with a different distance from the reference surface of the distance sensor at any time due to the cross-sectional profile typical of a twist drill, for example.
• this output signal - which has no simple connection with the geometry of the rotating tool - can be used to detect the state of wear and, in particular, to detect drill fractures.
• the device according to the invention generates the thresholds from the output signal of the distance sensor for a specific tool, for example used in a multi-spindle drilling system, on the basis of which the condition of the tool is evaluated.
• the distance sensor is arranged such that it detects it before, during and after the engagement due to the advance of the tool.
• the inventive method generates from the evaluation of the signal change frequency, the high-pass filtered signal change frequency and the signal change amplitude and / or the high-pass filtered signal change amplitude, but preferably from the correlation of the signal change frequency and the signal change amplitude (not filtered and / or high-pass filtered) Device evaluation thresholds, based on which the decision can be reliably made as to whether a tool is still in the system can remain or already has to be replaced:
• the sensors first record the drill tip and then, one after the other, the areas of the drill helix between the drill tip and drill shank.
• the signals measured in the "pre-process phase, process phase and post-process phase" are correlated with one another and enable a statement to be made about the condition of the tool and a statement about the trend, i.e. the "normal tool wear".
• the immediate detection of tool damage is possible.
• Fig. 1 shows schematically a device according to the invention
• Fig. 2 shows the sensor measuring surface on a
• FIGS. 4a and 4b a comparison of the sensor signals in the case of damaged and undamaged tools
• FIGS. 5a and 5b the sensor signal and the high-pass filtered sensor signal in the event of tool breakage
• FIGS. 6a and 6b the sensor signal and the high-pass filtered sensor signal in the event of tool breakage due to high 7, the high-pass filtered sensor signal before
• FIG. 1 schematically shows a device according to the invention for monitoring rotating tools, which is integrated in a two-spindle drill head 1 with spindles 11 and 12.
• a drill guide plate 15 is spring-mounted in a manner known per se, which also carries a catch bolt 16.
• each drill 17 or 18 is assigned radial displacement sensors 21, 22, 23, 24, which each have a signal which - as will be explained later - depends on an average weighted distance of the drill contour of a reference surface , in the direction of the coordinates x or y of the coordinate system shown in FIG. 1, that is to say perpendicular to the drill feed direction z.
• FIG. 2 explains the term “average weighted distance” introduced above.
• FIG. 2a shows a side view or a cross section through the tip of a typical twist drill.
• the size of the measurement spot of one of the radial displacement sensors 21 to 24 is also entered in FIG. 2a. As can be seen in FIG. 2a, the measuring spot has a diameter that is comparable to typical drill diameters.
• the output signal of the displacement sensor therefore does not correspond to the distance between the reference surface of the displacement sensor and a "point of the drill contour", as is the case with the known devices.
• the output signal of the displacement sensor is rather dependent on the course of the drill contour within the measurement spot, as is shown in FIGS. 2b and 2c.
• the evaluation or the sensitivity of the displacement sensor is also included over its entire "scanning spot".
• the sensor output signal does not correspond to the distance of a "point on the drill contour" from the displacement sensor, but rather to an average, weighted distance, the sensor output signal additionally also depending on the type of the displacement sensor and its displacement in the direction parallel to its scanning spot is dependent on the drill.
• Displacement sensors that can be used for this purpose are available, for example, under the following names
• FIG. 3a again shows a drill, for example the drill 17 and the associated sensor 22.
• the output connection of the sensor 22 is connected to a preamplifier 30, the output connection of which is connected directly to an evaluation circuit, for example a commercially available microcomputer 31, and once via a High-pass filter 32 is applied to the evaluation circuit 31.
• the evaluation circuit 31, which - as already stated, can be a microcomputer, but can also be a corresponding analog circuit - evaluates, on the one hand, the signal alternating frequency and the signal amplitude of the (amplified) sensor output signal and, on the other hand, the high-pass filtered signal Alternating frequency and the high-pass filtered signal amplitude and links the evaluated signals in the manner explained below.
• Figure 3b shows a typical sensor signal. The time in seconds is plotted on the abscissa, while the sensor signal is plotted in arbitrary units on the ordinate.
• FIG. 3c shows a typical high-pass filtered sensor signal. The time in seconds is plotted on the abscissa, while the high-pass filtered signal is plotted in arbitrary units on the ordinate.
• 3b and 3c show the time it takes the drill to complete a full revolution.
• the high-pass filtered sensor signal shown in FIG. 3c can also be interpreted “clearly” as the vibration path of the drill. It is expressly pointed out, however, that this descriptive interpretation is not exactly correct due to the measuring spot, which is averaged over the contour of the drill.
• FIG. 4a shows the sensor signal for an undamaged tool before the tool engagement
• FIG. 4b shows the sensor signal for a damaged tool before the tool engagement.
• successive maxima or successive minima differ by a certain value, which is, however, comparatively small.
• it has the mean distance, ie the curve indicating the distance averaged over the drill contour has a comparatively "smooth" course.
• FIG. 4b shows, this is not the case if the tool is damaged, i. H. if - as shown in this case, the drill tip is broken.
• FIGS. 5a and 5b show the sensor output signal and the high-pass filtered sensor output signal in the event of tool breakage due to low loads, i.e. H. if a damaged tool breaks.
• FIG. 5a shows that the change in the unfiltered sensor signal, which indicates an average weighted distance, is comparatively small.
• the high-pass-filtered sensor output signal which can be interpreted as an "oscillation path".
• FIGS. 6a and 6b show the resulting signal that occurs when a tool breaks due to high loads.
• FIG. 6b shows that the high-pass filtered output signal is not particularly meaningful at high loads even when the tool is initially undamaged.
• the non-high-pass filtered output signal which is shown in FIG. 6a, the appearance of large extreme values (in this case minimum values) clearly shows that the tool is broken.
• FIG. 7 shows that the occurrence of the tool engagement can also be determined from the high-pass filtered sensor signal which can be interpreted as an oscillation path.
• the signal Before the tool intervention, the signal is typically characterized in that it has a high amplitude at a low frequency. In contrast, a high amplitude occurs at high frequency during the tool engagement.
• FIGS. 8a and 8b show that it is possible to distinguish faults caused by environmental conditions from tool errors by correlating the two signals.
• FIGS. 8a and 8b show the case where there are chips between the drill and the sensor. It is typical of the occurrence of chips, which - as a rule - have nothing to do with damage to the tool, is that extreme values occur simultaneously in both signals.
• FIGS. 9a and 9b again show that tool damage, in this case damage to a cutting corner, by comparing successive extreme values, i.e. H. can be determined from successive maxima or from successive minima.
• FIG. 9a shows that in the case of an undamaged tool, successive minima differ only slightly, the reference point in the figure being 75 ⁇ m. However, it should be expressly pointed out that this drill output signal corresponding to a certain displacement does not correspond to an actual path difference due to the averaging over the contour.
• FIGS. 10a to 10c show the differences between the high-pass filtered sensor signal during a tool intervention in a series of successive tool interventions.
• FIG. 10a shows the fourth hole
• FIG. 10b the fiftieth
• FIG. 10c the three hundredth hole with the same tool.
• the high-pass filtered sensor signals differ considerably due to the increasing wear of the tool and can therefore be used to determine normal wear without direct damage to the tool.
• FIG. 11a shows the frequency response of successive bores, namely FIG. 11a the frequency response during the sixty-fourth bore and FIG. 11b the frequency response during the two hundred and twenty-third bore.
• the frequency responses - as long as the tool is not damaged, but only worn - are topologically the same, that is, they can also be used to determine a tool confirmation.
• FIGS. 12a and 12b show the sensor signal and the high-pass filtered sensor signal when

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Human Computer Interaction (AREA)
• Manufacturing & Machinery (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Automation & Control Theory (AREA)
• Drilling And Boring (AREA)
• Machine Tool Sensing Apparatuses (AREA)

Applications Claiming Priority (2)

Publications (1)

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ID=6361142

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• 1988
  • 1988-08-18 DE DE19883828101 patent/DE3828101A1/de active Granted
  • 1988-10-06 EP EP19880908160 patent/EP0429443A1/de not_active Withdrawn
  • 1988-10-06 WO PCT/DE1988/000616 patent/WO1990002022A1/de not_active Application Discontinuation

Non-Patent Citations (1)

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