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EP-4737041-A1 - SYSTEM AND METHOD FOR CHARACTERIZING AN ELECTRICAL DISCHARGE DRILLING PROCESS USING ULTRASOUND

EP4737041A1EP 4737041 A1EP4737041 A1EP 4737041A1EP-4737041-A1

Abstract

Systems (10) and methods for characterizing an electrical discharge drilling process using ultrasound are provided. The characterization of the electrical discharge drilling process facilitates estimating cycle times and electrode (18) consumptions for future electrical discharge drilling tasks. An electrical discharge drilling machine includes a base (14) for supporting a workpiece (16), an electrode (18) operable to drill a hole (20) in the workpiece (16) using an electrical discharge, and an ultrasonic probe (30) installed on the base (14) and oriented toward the workpiece (16) when the workpiece (16) is supported by the base (14).

Inventors

  • ING, VISAL
  • LETENDRE, Etienne
  • MANSUR RODRIGUES FILHO, Jorge Franklin

Assignees

  • PRATT & WHITNEY CANADA CORP.

Dates

Publication Date
20260506
Application Date
20251024

Claims (15)

  1. An electrical discharge drilling machine comprising: a base (14; 114; 214; 314) for supporting a workpiece (16); an electrode (18) operable to drill a hole (20) in the workpiece (16) using an electrical discharge when the workpiece (16) is supported by the base (14; 114; 214; 314); and an ultrasonic sensor (30; 130; 230) installed on the base (14; 114; 214; 314) and oriented toward a location of the workpiece (16) when the workpiece (16) is supported by the base (14; 114; 214; 314), the ultrasonic sensor (30; 130; 230) being operable to sense a depth (D) of the hole (20) during drilling of the hole (20) by: emitting an input sound wave (32) into the workpiece (16); and sensing a reflected sound wave reflected from a closed end (20B) of the hole (20).
  2. The electrical discharge drilling machine as defined in claim 1, wherein the ultrasonic sensor (30; 130; 230) is received inside an aperture formed in the base (14; 114; 214; 314).
  3. The electrical discharge drilling machine as defined in claim 1 or 2, wherein: the ultrasonic sensor (30; 130; 230) is one of a plurality of ultrasonic sensors; and the ultrasonic sensors are received inside respective apertures formed in the base (14; 114; 214; 314).
  4. The electrical discharge drilling machine as defined in claim 1, 2 or 3, wherein the electrode (18) includes a rotatable tube configured to receive a flushing liquid (22) therethrough while drilling the hole (20) in the workpiece (16).
  5. The electrical discharge drilling machine as defined in claim 4, wherein a longitudinal axis (EA) of the electrode (18) is non-normal to a support surface (14A; 114A; 214A; 314A) of the base (14; 114; 214; 314) configured to support the workpiece (16).
  6. A system (10; 110; 210) for characterizing an electrical discharge drilling process using ultrasound, the system (10; 110; 210) comprising: a workpiece (16) having a first side (16A) and a second side (16B) opposite the first side (16A); a rotatable tubular electrode (18) configured to drill a hole (20) in the workpiece (16) from the first side (16A) of the workpiece (16) using an electrical discharge; and an ultrasonic sensor (30; 130; 230) coupled to the second side (16B) of the workpiece (16) and oriented toward the rotatable tubular electrode (18), the ultrasonic sensor (30; 130; 230) being operable to sense a depth (D) of the hole (20) during drilling of the hole (20) by: emitting an input sound wave (32) into the workpiece (16) via the second side (16B) of the workpiece (16); and sensing a reflected sound wave reflected from a closed end (20B) of the hole (20) via the second side (16B) of the workpiece (16).
  7. The system (10; 110; 210) as defined in claim 6, comprising a base (14; 114; 214; 314) supporting the workpiece (16), the ultrasonic sensor (30; 130; 230) being installed on the base (14; 114; 214; 314), wherein, optionally, the ultrasonic sensor (30; 130; 230) is received inside an aperture formed in the base (14; 114; 214; 314), wherein, further optionally: the ultrasonic sensor (30; 130; 230) is one of a plurality of ultrasonic sensors; and the ultrasonic sensors are received inside respective apertures formed in the base (14; 114; 214; 314).
  8. The system (10; 110; 210) as defined in claim 7, wherein a longitudinal axis (EA) of the rotatable tubular electrode (18) is non-normal to a support surface (14A; 114A; 214A; 314A) of the base (14; 114; 214; 314) supporting the workpiece (16), wherein, optionally, the ultrasonic sensor (30; 130; 230) has a field of view that includes both an entrance (20A) of the hole (20) and the closed end (20B) of the hole (20) at a final depth of the hole (20).
  9. The system (10; 110; 210) as defined in claim 6, 7 or 8, wherein the ultrasonic sensor (30; 130; 230) is part of an ultrasonic probe that is in contact with the second side (16B) of the workpiece (16), wherein, optionally, the ultrasonic probe is part of a base (14; 114; 214; 314) supporting the workpiece (16) during the drilling of the hole (20).
  10. A method of characterizing an electrical discharge drilling process using ultrasound, the method comprising: drilling a hole (20) in a workpiece (16) from a first side (16A) of the workpiece (16) using an electrical discharge delivered using a rotating electrode (18); during the drilling of the hole (20), sensing a depth (D) of the hole (20) using ultrasound from a second side (16B) of the workpiece (16) opposite the first side (16A) of the workpiece (16), the sensing of the depth (D) of the hole (20) including: emitting an input sound wave (32) into the workpiece (16) via the second side (16B) of the workpiece (16); and sensing a reflected sound wave reflected from a closed end (20B) of the hole (20) via the second side (16B) of the workpiece (16).
  11. The method as defined in claim 10, comprising determining a consumption of the rotating electrode (18) by: sensing a first depth of the hole (20) when a holder of the rotating electrode (18) is at a first position during the drilling of the hole (20); and after sensing the first depth of the hole (20), sensing a second depth of the hole (20) when the holder of the rotating electrode (18) is at a second position different from the first position during the drilling of the hole (20).
  12. The method as defined in claim 10 or 11, wherein sensing the depth of the hole (20) is performed using an ultrasonic probe (30; 130; 230) embedded into a base (14; 114; 214; 314) supporting the workpiece (16) during the drilling of the hole (20), wherein, optionally: the hole (20) is a first hole; the ultrasonic probe (30; 130; 230) is a first ultrasonic probe; and the method includes: drilling a second hole (20) in the workpiece (16) from the first side (16A) of the workpiece (16) using the rotating electrode (18) or another rotating electrode (18); and during the drilling of the second hole (20), sensing a depth of the second hole (20) using a second ultrasonic probe (30; 130; 230) embedded into the base (14; 114; 214; 314).
  13. The method as defined in claim 10, 11 or 12, wherein sensing the depth of the hole (20) using ultrasound includes sensing the reflected sound wave simultaneously with the electrical discharge.
  14. The method as defined in claim 10, 11, 12 or 13, comprising: constructing a data library (36) including data indicative of a plurality of depths of the hole (20) sensed during the drilling of the hole (20) and actual process parameters used to drill the hole (20); receiving a task description (48) describing a future electrical discharge drilling task; using the task description (48) and the data library (36), generating one or more estimated process parameters (46) for the future electrical discharge drilling task; and using the one or more estimated process parameters (46) to perform the future electrical discharge drilling task.
  15. The method as defined in claim 14, wherein the one or more estimated process parameters (46) include: a cycle time for performing the future electrical discharge drilling task; an electrode consumption for performing the future electrical discharge drilling task; a spark generator (24) setting suitable for performing the future electrical discharge drilling task; and/or a setting of an electrical discharge machine used for performing the future electrical discharge drilling task.

Description

TECHNICAL FIELD The disclosure relates generally to electrical discharge machining, and more particularly to characterizing an electrical discharge drilling process. BACKGROUND Electrical discharge drilling is used for precision drilling in aerospace-grade metals with low machinability. Drilling speed using electrical discharge drilling can depend on many process parameters and evolving dynamic conditions such as injection pressure, cleaning efficiency and electrode consumption, which can vary non-linearly. Some electrical discharge machines can adapt to the real conditions inside the hole being drilled such that if there is excessive debris, the next spark will not be generated and the drilling feed rate will adapt accordingly. The electrode consumption may also vary with increased hole depth as the injection of flushing liquid becomes less effective. Estimating and planning for electrical discharge drilling tasks is challenging. SUMMARY In one aspect, the disclosure describes an electrical discharge drilling machine comprising: a base for supporting a workpiece;an electrode operable to drill a hole in the workpiece using an electrical discharge when the workpiece is supported by the base; andan ultrasonic sensor installed on the base and oriented toward a location of the workpiece when the workpiece is supported by the base, the ultrasonic sensor being operable to sense a depth of the hole during drilling of the hole by: emitting an input sound wave into the workpiece; andsensing a reflected sound wave reflected from a closed end of the hole. The ultrasonic sensor may be received inside an aperture formed in the base. The ultrasonic sensor may be one of a plurality of ultrasonic sensors. The ultrasonic sensors may be received inside respective apertures formed in the base. The electrode may include a rotatable tube configured to receive a flushing liquid therethrough while drilling the hole in the workpiece. A longitudinal axis of the electrode is non-normal to a support surface of the base configured to support the workpiece. Embodiments may include combinations of the above features. In another aspect, the disclosure describes a system for characterizing an electrical discharge drilling process using ultrasound. The system comprises: a workpiece having a first side and a second side opposite the first side;a rotatable tubular electrode configured to drill a hole in the workpiece from the first side of the workpiece using an electrical discharge; andan ultrasonic sensor coupled to the second side of the workpiece and oriented toward the rotatable tubular electrode, the ultrasonic sensor being operable to sense a depth of the hole during drilling of the hole by: emitting an input sound wave into the workpiece via the second side of the workpiece; andsensing a reflected sound wave reflected from a closed end of the hole via the second side of the workpiece. The system may comprise a base supporting the workpiece. The ultrasonic sensor may be installed on the base. The ultrasonic sensor may be received inside an aperture formed in the base. The ultrasonic sensor may be one of a plurality of ultrasonic sensors. The ultrasonic sensors may be received inside respective apertures formed in the base. A longitudinal axis of the rotatable tubular electrode may be non-normal to a support surface of the base supporting the workpiece. The ultrasonic sensor may have a field of view that includes both an entrance of the hole and the closed end of the hole at a final depth of the hole. The ultrasonic sensor may be part of an ultrasonic probe that is in contact with the second side of the workpiece. The ultrasonic probe may be part of a base supporting the workpiece during the drilling of the hole. Embodiments may include combinations of the above features. In a further aspect, the disclosure describes a method of characterizing an electrical discharge drilling process using ultrasound. The method comprises: drilling a hole in a workpiece from a first side of the workpiece using an electrical discharge delivered using a rotating electrode;during the drilling of the hole, sensing a depth of the hole using ultrasound from a second side of the workpiece opposite the first side of the workpiece, the sensing of the depth of the hole including: emitting an input sound wave into the workpiece via the second side of the workpiece; andsensing a reflected sound wave reflected from a closed end of the hole via the second side of the workpiece. The method may comprise determining a consumption of the rotating electrode by: sensing a first depth of the hole when a holder of the rotating electrode is at a first position during the drilling of the hole; andafter sensing the first depth of the hole, sensing a second depth of the hole when the holder of the rotating electrode is at a second position different from the first position during the drilling of the hole. Sensing the depth of the hole may be performed using an ultrasonic probe