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WO2007065959A1 - Procede de controle de la formation de bavures dans des processus de perçage de pieces - Google Patents

Procede de controle de la formation de bavures dans des processus de perçage de pieces Download PDF

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Publication number
WO2007065959A1
WO2007065959A1 PCT/ES2005/000665 ES2005000665W WO2007065959A1 WO 2007065959 A1 WO2007065959 A1 WO 2007065959A1 ES 2005000665 W ES2005000665 W ES 2005000665W WO 2007065959 A1 WO2007065959 A1 WO 2007065959A1
Authority
WO
WIPO (PCT)
Prior art keywords
value
zone
established
hole
signal
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/ES2005/000665
Other languages
English (en)
Spanish (es)
Inventor
Begoña PEÑA PELLICER
Gorka ARAMENDI LARRAÑAGA
Mª Asunción RIVERO RASTRERO
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Asociacion Centro De Investigacion De Fabricacion De Alto Rendimiento
Original Assignee
Asociacion Centro De Investigacion De Fabricacion De Alto Rendimiento
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Asociacion Centro De Investigacion De Fabricacion De Alto Rendimiento filed Critical Asociacion Centro De Investigacion De Fabricacion De Alto Rendimiento
Priority to PCT/ES2005/000665 priority Critical patent/WO2007065959A1/fr
Publication of WO2007065959A1 publication Critical patent/WO2007065959A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23B—TURNING; BORING
    • B23B35/00—Methods for boring or drilling, or for working essentially requiring the use of boring or drilling machines; Use of auxiliary equipment in connection with such methods
    • 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
    • B23Q17/0961—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 by measuring power, current or torque of a motor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23B—TURNING; BORING
    • B23B2215/00—Details of workpieces
    • B23B2215/04—Aircraft components
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23B—TURNING; BORING
    • B23B2222/00—Materials of tools or workpieces composed of metals, alloys or metal matrices
    • B23B2222/04—Aluminium

Definitions

  • Drilling operations usually produce burrs on both the inlet and outlet surfaces. They are formed as a result of the plastic deformation, which largely depends on the ductility of the material. Burrs during drilling constitute an unavoidable obstacle in the automation of assembly processes due to the need for a deburring stage. Burrs are a source of dimensional errors and misalignments; they can cause short circuits in electrical components; reduce the fatigue life of riveted parts; and can act as initial cracking points. For these reasons, the reduction in the quality of drilling operations is a crucial problem, especially for the aeronautical and aerospace industries. In these small burrs are allowed, below a certain height that is between 100 and 150 microns.
  • the method of the invention is characterized by being a method of monitoring the formation of burrs in parts drilling processes in which a drill head, the head motor regulator, is used, previously establishing a fixed process of drilling in which the value of the process variables is set under the production conditions and among them the value of one or more speeds of advance, in which in each process of drilling parts: a) the admissible height is set burr -A- b) the signal associated with the torque from the head motor regulator is captured, the "cutting zone” comprised between the point where the drill bit touches the input surface in the material is determined in said signal until The drill is again outside the hole after the recoil of the head; c) several zones are defined within the "cutting zone”: the "exit point” is established as the point at which the tip of the drill bit crosses the exit surface of the hole; the "exit zone” is established as the zone immediately after the "exit point”; the "reference level” (RL) is calculated as the average value reached by the signal in the area in which the drill bit crosses
  • N Minimun / RL e) the relative minimum value is calculated for the set process and a comparison relative minimum value (Nc) is established with a pre-established tolerance; f) the signal from the head motor regulator is captured during the industrial drilling process in production, the relative minimum value (N) for each hole is calculated in the "cutting zone", deciding that the height of the burr is admissible if said value (N) is less than the value of the relative minimum of comparison (Nc) with the pre-established tolerance: N ⁇ Nc.
  • the relative maximum value (M) is defined as the quotient between the maximum value (Maximun) reached by the signal in the "pre-departure zone” and the “reference level” (RL):
  • M Maximun / RL b) the relative maximum value is calculated for the fixed process and a comparison relative maximum value (Mc) is established with a pre-established tolerance; c) the signal from the head motor regulator is captured during the industrial drilling process in production, calculated in
  • the "cutting zone” is the relative maximum value (M) for each hole, deciding that the height of the burr is admissible if said value (M) is less than the value of the relative minimum of comparison (Mc) with the pre-established tolerance: M ⁇ Mc. It is also characterized because: a) a neural network is designed and trained that uses the magnitude N defined in 1 d) as an input, the level of burr will be established as an output of the network, which may adopt different defined burr levels for the interest of the user; b) the signal from the head motor regulator is captured during the industrial drilling processes in production, the value of the magnitudes used as inputs of the neural network is calculated for each hole, the output of the neural network will indicate the level burr.
  • a neural network is designed and trained that uses the magnitudes W, H, S defined in 2d as inputs, the level of burr will be established as an output of the network, which may adopt different levels of burr defined by user interest; b) the signal from the head motor regulator is captured during the industrial drilling processes in production, the value of the magnitudes used as inputs of the neural network is calculated for each hole, the output of the neural network will indicate the level burr.
  • a neural network is designed and trained that uses the magnitude M defined in 3d as an input), the level of burr will be established as an output of the network, which may adopt different levels of burr defined by the interest of the user; b) the signal from the head motor regulator is captured during the industrial drilling processes in production, the value of the magnitudes used as inputs of the neural network is calculated for each hole, the output of the neural network will indicate the level burr.
  • Figure 1 is a representation in torque / time coordinates of the complete signal of the regulator associated with the spindle motor.
  • Figure 2 are representations in torque / penetration coordinates (mm).
  • Figure 3 is a representation in torque / time coordinates of an estimate of the point of entry of the drill bit into the material as the intersection between two lines.
  • Figure 4 is a representation in torque / time coordinates of the cutting zone with the pre-exit zone, exit zone, post-exit zone, exit point and reference level: a) with a forward speed b) with two forward speeds.
  • Figure 5 is a representation of Figure 4b with the five magnitudes sensitive or fundamental to burr formation in the specific case of using two forward speeds.
  • Figure 6 are four representations (a), (b), (c), (d) of torque / penetration coordinates (mm) of signals with different burr level changing the advance speed mm / rev. A non-limiting practical embodiment of the present invention is described below.
  • test material has been aluminum in its alloys used in aeronautics. Signal acquisition system
  • the analog output of the regulator corresponding to the spindle motor has been captured, which is associated with the torque. Internally it is a current signal in the motor loop, but externally it is presented as a voltage signal in a range between -1 0 and + 1 0 V. It is convenient to adjust the full scale to use the resolution of the measurement to the maximum.
  • the signal from the spindle motor is an indirect measure of torque, which compared to direct measurements has the advantage of not needing additional devices and facilitating the implementation of the monitoring method in the machine's own CNC control.
  • Figure 1 shows a signal captured during an example drilling test in which a single hole was made.
  • the first range of large oscillations corresponds to the "Acceleration zone” of the head.
  • the torque decreases almost to zero.
  • the "Approach Zone” of the tool begins until the work material.
  • the measured torque grows in the "Cutting zone", comprised between the point where the drill bit touches the input surface in the material until the drill bit is out of the hole again after the head recoils.
  • This area includes both the area in which the drill bit passes through the material in the direction and direction of drilling, and the backward travel of the drill bit in the reverse direction until the tip of the tool returns to the entrance surface of the hole.
  • the “Deceleration zone” represented in the negative plane.
  • the signal from the regulator can be rescaled in torque units with the appropriate calibration. This obviously depends on the power curve of the particular machine. In our particular case, the transformation is reduced to the following equation:
  • Figure 2 shows two examples of filtered signals, one in Fourier space with a filter.
  • the "exit zone” is established as the zone immediately after the "exit point", which comprises from when the tip of the drill bit touches the exit surface of the hole until it begins to recede;
  • the "Reference level” (RL) is defined as the average value reached by the signal in the area in which the drill bit passes through the internal section of the hole in which it is approximately constant for fixed process conditions.
  • Figure 4a shows an example in which a single forward speed has been used throughout the entire hole, while in Figure 4b two different forward speeds have been used.
  • the reference level is calculated as the average of the value of the signal in the central part of the hole, while in the second case it is calculated as the average in the section corresponding to the second speed. It would be calculated in a similar way if 3 speeds were used along the length of the hole, only calculated in the section corresponding to the last speed.
  • a fixed drilling process is established in which the value of the process variables is set under the conditions of production that interest the user (machine, tool, process parameters, etc.).
  • the fundamental parameter is the value of the relative minimum (N).
  • a comparison value can be established for each of the attributes chosen by different standard methods: minimum that satisfies the requirements, linear adjustment for least squares, fuzzy logic methods, etc. The burr will be acceptable if it is successively fulfilled: N ⁇ Nc , M ⁇ Mc, W ⁇ Wc, H ⁇ Ho, S> Sc, (if all attributes are not chosen, the same order is followed for the chosen ones).
  • the acceptable burr height limit has been set at 1 27 microns (Hb).
  • the signals with a sampling frequency of 5000 Hz have been captured.
  • the signal has been represented as a function of the depth of the hole, that is, the time has been converted into depth (mm), taking the point where the drill bit is zero. touch the material.
  • TN 16.97 (N m) is the nominal torque of the machine equivalent to 5 (V) and VT is the measured voltage of the head regulator. •
  • the established comparison values are:
  • the first method of monitoring burrs during drilling has been developed.
  • the algorithm is based on the analysis of the signals coming from the spindle motor regulator. This facilitates and lowers the implementation of the method in the control to use it automatically.
  • the reliability of this method is above 92% for an extensive parameter range under high speed dry drilling conditions for aluminum alloys, for example, Al 7075-T6.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Numerical Control (AREA)
  • Drilling And Boring (AREA)

Abstract

La présente invention concerne un procédé permettant de contrôler la formation de bavures dans des processus de perçage de pièces, fondé sur des signaux internes associés au couple, obtenus par le régulateur du moteur de la tête et utilisés pour détecter la formation de bavures indésirables durant les processus de perçage. Il a été démontré que cinq caractéristiques du signal sont associées à la hauteur de la bavure, ces caractéristiques étant toutefois relativement indépendantes des paramètres du processus. Les expériences ont été menées sur de l'aluminium aéronautique Al 7075-T6 dans des conditions de vitesse élevée. Un algorithme basé sur des seuils, capable de distinguer des bavures ne répondant pas aux exigences, avec une fiabilité supérieure à 92 %, pour l'éventail de paramètres testés, a été mis au point. Cet algorithme, employé de manière appropriée, peut être utilisé comme un système de contrôle de la qualité des opérations de perçage. L'invention s'applique à l'aéronautique.
PCT/ES2005/000665 2005-12-07 2005-12-07 Procede de controle de la formation de bavures dans des processus de perçage de pieces Ceased WO2007065959A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/ES2005/000665 WO2007065959A1 (fr) 2005-12-07 2005-12-07 Procede de controle de la formation de bavures dans des processus de perçage de pieces

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/ES2005/000665 WO2007065959A1 (fr) 2005-12-07 2005-12-07 Procede de controle de la formation de bavures dans des processus de perçage de pieces

Publications (1)

Publication Number Publication Date
WO2007065959A1 true WO2007065959A1 (fr) 2007-06-14

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH04110708A (ja) * 1990-08-31 1992-04-13 Suzuki Motor Corp 表面測定装置
JPH10296589A (ja) * 1997-04-25 1998-11-10 Yamazaki Mazak Corp ドリル切損予知装置及びドリル切損予知方法
US20030187624A1 (en) * 2002-03-27 2003-10-02 Joze Balic CNC control unit with learning ability for machining centers

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH04110708A (ja) * 1990-08-31 1992-04-13 Suzuki Motor Corp 表面測定装置
JPH10296589A (ja) * 1997-04-25 1998-11-10 Yamazaki Mazak Corp ドリル切損予知装置及びドリル切損予知方法
US20030187624A1 (en) * 2002-03-27 2003-10-02 Joze Balic CNC control unit with learning ability for machining centers

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN 26 February 1999 (1999-02-26) *
PATENT ABSTRACTS OF JAPAN vol. 016, no. 357 31 July 1992 (1992-07-31) *

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