WO2004054747A2 - Dispositif de taraudage a vibration - Google Patents

Dispositif de taraudage a vibration Download PDF

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Publication number
WO2004054747A2
WO2004054747A2 PCT/US2003/039157 US0339157W WO2004054747A2 WO 2004054747 A2 WO2004054747 A2 WO 2004054747A2 US 0339157 W US0339157 W US 0339157W WO 2004054747 A2 WO2004054747 A2 WO 2004054747A2
Authority
WO
WIPO (PCT)
Prior art keywords
vibration
tapping
screw
assisted
flexural members
Prior art date
Application number
PCT/US2003/039157
Other languages
English (en)
Other versions
WO2004054747A3 (fr
Inventor
Bi Zhang
Original Assignee
University Of Connecticut
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 University Of Connecticut filed Critical University Of Connecticut
Priority to AU2003293471A priority Critical patent/AU2003293471A1/en
Publication of WO2004054747A2 publication Critical patent/WO2004054747A2/fr
Publication of WO2004054747A3 publication Critical patent/WO2004054747A3/fr

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23G—THREAD CUTTING; WORKING OF SCREWS, BOLT HEADS, OR NUTS, IN CONJUNCTION THEREWITH
    • B23G1/00—Thread cutting; Automatic machines specially designed therefor
    • B23G1/44—Equipment or accessories specially designed for machines or devices for thread cutting
    • B23G1/46—Equipment or accessories specially designed for machines or devices for thread cutting for holding the threading tools
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23B—TURNING; BORING
    • B23B29/00—Holders for non-rotary cutting tools; Boring bars or boring heads; Accessories for tool holders
    • B23B29/04—Tool holders for a single cutting tool
    • B23B29/12—Special arrangements on tool holders
    • B23B29/125—Vibratory toolholders
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23G—THREAD CUTTING; WORKING OF SCREWS, BOLT HEADS, OR NUTS, IN CONJUNCTION THEREWITH
    • B23G1/00—Thread cutting; Automatic machines specially designed therefor
    • B23G1/02—Thread cutting; Automatic machines specially designed therefor on an external or internal cylindrical or conical surface, e.g. on recesses
    • B23G1/04—Machines with one working-spindle

Definitions

  • the invention relates to the field of vibration-assisted machining processes and more particularly to methods and devices for vibration- assisted tapping.
  • Ultrasonic (> 20KHz) screw-vibration has been applied to assist the tapping process on pure aluminum, and found that chip thickness and tapping torque were reduced, while the surface integrity and accuracy of the threads were significantly improved (Suzuki et al. (1991)).
  • Shamoto et al (1994 & 1996) applied a synchronized two- directional vibration to the machining of copper to form an eliptical vibration cutting pattern that reduces chip thickness, cutting forces and the specific energy of material removal while significantly improving the surface integrity of the machined surface.
  • the results of vibration assisted machining and the above discussed experiments indicate that application of vibration to the tapping process may reduce tapping torque, lengthen tool life and improve the quality of the thread produced.
  • vibration-assistance device that can be incorporated into existing thread-tapping equipment.
  • a vibration-assistance device would permit the resulting vibration to be tailored to a particular tapping process and will require little or no modification of the existing thread-tapping equipment.
  • the torque required for tapping includes the torque required for material removal as well as relief face friction due to spring back (elastic recovery) of the machined surface. Vibration tapping can reduce tapping torque mostly because the workpiece surface is repeatedly cut, each successive cut removing a further portion of the material bearing on the relief face of the tap. The more times the workpiece surface is cut, the smaller the frictional force should be.
  • Repeated cutting is a function of vibration direction, amplitude and frequency. Vibration above a certain frequency tends to reduce the amplitude of cutting face oscillation, thereby reducing the overlapping length of repeated cutting. Axial vibration adversely affects the tapping process by increasing thread error. Further axial vibration fails to improve the number of cutting times because the tap cutting takes place primarily in an axial direction with a small torsional element. Intuitively, torsional vibration should have a beneficial effect on thread tapping by increasing repeated cutting, as experimentation has proved. However, torsional cutting does not account for the axial component of a helix defined by the thread being cut.
  • an exemplary embodiment of a vibration-assisted tapping device comprises an elastic frame surrounding a source of axial vibration.
  • the frame includes an upper plate and lower plate connected by angled flexural members.
  • the axial vibrator is fixed to one of the upper or lower plates and biased against the other of the upper or lower plates to apply its axial vibratory force to the elastic frame.
  • the flexural members are inclined relative to a longitudinal axis of the device at an angle equal to or greater than the lead angle of the thread being tapped.
  • An exemplary embodiment of the frame is machined from a single piece of spring steel.
  • a plurality of flexural members is arranged around the periphery of the frame to connect the upper plate to the lower plate.
  • a piezoelectric vibratory actuator is aligned with the central axis of the frame and biased or preloaded relative to the frame such that the axial vibratory motion is efficiently transmitted to the frame.
  • Axial stretching of the frame by the actuator is translated by the inclined flexural members into relative movement between the upper and lower plates having axial and torsional components.
  • the configuration of the frame i.e., the angle of the flexural members, the stiffness and elasticity of the frame, the frequency and amplitude of the vibration applied, combine to produce a relative movement between the upper and lower plates of the frame. This relative movement may be substantially aligned with a helix defined by the thread being tapped.
  • a driver circuit operatively connected to the vibratory actuator allows the frequency of the vibration as well as the effective force, and hence the amplitude of the vibration to be varied.
  • a torque sensor is arranged to measure the torque required for tapping over a range of vibration frequencies and amplitudes. This arrangement allows for testing to determine the most effective combination of vibration frequency and amplitude for a particular tapping process.
  • An object of the invention is to provide a new and improved vibration assisted tapping device that is inexpensive, technologically simple and improves the speed and accuracy of thread tapping.
  • Another object of the present invention is to provide a new and improved vibration-assisted tapping device that produces a screw vibratory motion substantially aligned with a helix defined by the thread being tapped.
  • a further object of the present invention is to provide a new and improved vibration-assisted tapping device and a method for matching the vibration assistance to a particular thread tapping process.
  • Figure 1 is an elevational exterior view of an exemplary frame for translating axial vibration into vibration having an axial and torsional component in accordance with a first aspect of the present invention
  • Figure 2 is an exemplary tapping arrangement incorporating an alternative exemplary frame supporting a workpiece
  • Figure 3 is an exterior view of a vibration-assisted tap incorporating an alternative exemplary frame in accordance with an aspect of the present invention
  • Figure 4 illustrates an exemplary screw thread for which a tapping operation may be carried out by a vibration-assisted tapping device in accordance with the present invention
  • Figures 4.2.1 - 4.2.16 graphically illustrate tapping torque ranges as a function of driving frequency in Hz and driving voltage, while associated Tables 4.2.1 - 4.2.16 illustrate the experimental parameters and resulting data for the corresponding Figures;
  • Figure 5 is a sectional view through a workpiece holder for use in conjunction with the vibration-assisted tap holder shown in Figure 3;
  • Figure 6 is a functional block diagram of a system for applying the experimental parameters of Tables 4.2.1 - 4.2.16 to particular tapping operations and recording the resulting tapping torque data.
  • an aspect of the present invention relates to a frame 10 configured to translate an applied axial vibration into vibration having axial and torsional components.
  • the exemplary frame 10 of Figure 1 comprises a top plate 12 connected to a bottom plate 16 by a plurality of angled flexural members 14.
  • the exemplary frame 10 is machined from a single piece of spring steel, although alternative materials and methods of construction may occur to one of skill in the art.
  • the bottom plate 16 is in the form of a ring integrally connected to the bottom of the flexural members 14. This bottom plate configuration is a result of machining the frame 10 from a single piece of steel.
  • the exemplary frame 10 incorporates six flexural members 14 connecting the upper plate 12 to the lower plate 16. Each of the six flexural members 14 is inclined relative to an axis A of the frame 10.
  • the frame 10 and its angled flexural members 14 are configured such that, when exposed to that portion of the axial vibration which seeks to push the upper and lower plates apart, this axial spreading is translated into relative movement between the upper and lower plates having both an axial and torsional component.
  • this movement will be referred to as "screw vibration” and is illustrated as reciprocating movement generally along a path illustrated by arrow 40. It can be seen from Figure 1 that arrow 40 defines a path having both an axial component and a torsional component.
  • the incline angle 0 S , elasticity and stiffness of the flexural members 14 are calculated to produce a screw vibration 40 having an angle relative to a plane normal to the frame axis A that is substantially equal to or greater than the lead angle 0 of the thread being cut.
  • Figure 4 illustrates an exemplary screw 30 having a single-lead thread 32.
  • the illustrated single-lead thread 32 defines a helix around a central axis B.
  • the thread 32 has a lead angle 0 relative to a plane P normal to the axis B of the helix defined by the thread 32.
  • the frame 10 is configured to translate axial vibration into screw vibration substantially aligned with the lead angle of the thread being cut.
  • a flexural member angle 0 S relative to the frame axis A equal to or greater than the lead angle 0 L of the thread being cut has proven to produce screw vibration which produces a greater reduction in tapping torque than an equivalent torsional vibration.
  • Screw vibration along path 40 is more closely aligned with the helical configuration of the thread being cut, thereby improving the accuracy of the resulting threads.
  • the inventive frame may be incorporated into a work surface such as that of a work table and used to support the workpiece as shown in Figure 2 or it may be incorporated into a tool holder, chuck or collet such as a tap holder 60 as shown in Figure 3.
  • the frame 10a illustrated in Figure 2 incorporates four flexural members 14 connecting the top plate 12 to the bottom plate 16.
  • a piezoelectric vibratory actuator 50 is arranged along the axis of the frame.
  • the actuator/frame assembly is configured such that the actuator 50 is compressed or preloaded between the upper and lower plates 12, 16.
  • Each of the actuator 50 and frame 10a have an axial stiffness.
  • the axial stiffness of the actuator 50 is approximately equal to the axial stiffness of the frame 10a. This relationship has proven to result in an efficient translation of actuator vibration into screw vibration by the frame 10a.
  • Figure 3 shows an exemplary vibration-assisted tap holder 60 incorporating a frame 10b and vibratory actuator 50. It will be noted that the position of the upper and lower plates 12, 16 of the frame 10b are reversed with respect to the orientation of the upper and lower plates shown in Figure 2. This frame 10b is reversed so that the resulting screw vibration path 40 is substantially aligned with the path of thread cutting. In Figure 3, clockwise rotation of the tap 62 to cut a conventional right hand thread is reinforced by screw vibration along path 40 produced by the inventive frame 10b and vibratory actuator 50.
  • a left-hand thread would be tapped with a vibration-assisted tap holder with flexural members inclined at an angle of -0s relative to axis A.
  • the opposite helical thread configuration of the left-hand thread would require a corresponding opposite angular inclination of the flexural members 14.
  • FIG 2 it is the workpiece to which the screw vibration is being applied.
  • the illustrated orientation of frame 10a and vibratory actuator 50 produces a screw vibration along a path 40 substantially aligned with the path of thread cutting made by the tap 62.
  • the configuration illustrated in Figure 2 is practical only if the workpiece 64 is small enough to vibrate.
  • larger workpieces and/or larger tap diameters will have greater tapping torque levels and greater masses to be vibrated and will likely require a vibratory actuator capable of producing a larger force to produce satisfactory results.
  • FIGs 2, 3, 5 and 6 illustrate a basic configuration for an adaptive vibration assisted tapping device in accordance with several aspects of the present invention.
  • the workpiece holder 80 is mounted to a torque sensor 70 arranged to measure the tapping torque applied to the workpiece 64.
  • Figure 5 illustrates an alternative workpiece holder 80a for use in conjunction with the vibration assisted tap holder of Figure 3.
  • the workpiece holder 80a is also supported on a torque sensor 70.
  • a torque sensor may also be incorporated into a vibration assisted tap holder such as that illustrated in Figure 3.
  • the piezoelectric vibratory actuators 50 of Figures 2 and 3 are responsive to oscillating signals that may take various forms such as a square wave, sine wave, or the like. The amplitude (in volts) and frequency of the driving signal determine the force and frequency of the vibration produced by the actuators.
  • Figure 6 illustrates a system for automating the application of different vibration patterns to a tapping operation and for collecting torque data associated with each vibration pattern.
  • a computer 100 controls the piezoelectric driver 130 and receives torque sensor readings from a charge amplifier 120 via an interface box 110.
  • the computer 100 may be programmed to cycle through a range of vibration frequencies and driving voltages and record the resulting tapping torque for each frequency/driving voltage point. The resulting data can be used to determine the most effective vibration pattern for a particular tapping operation.
  • This arrangement might be incorporated into a machine tool for the purpose of producing an adaptive machine tool. When the adaptive machine tool has cycled through the available range of frequencies and driving voltages, it may be programmed to return to the frequency/driving voltage combination that produced the greatest tapping torque reduction.
  • the system of Figure 6 might be used to configure a tapping machine to perform many substantially identical tapping operations. The tapping machine could be configured to produce vibration assistance at the frequency and amplitude that was determined experimentally to provide the greatest tapping torque reduction.
  • Tables 4.2.1 - 4.2.16 and related Figures 4.2.1 - 4.2.16 are constructed from data gathered from a series of tapping operations by a system such as that illustrated in Figure 6.
  • FIG. 4.2.1 - 4.2.16 graphically illustrate the experimental results in terms of tapping torque ranges as a function of driving frequency in Hz and driving voltage.
  • the most effective vibratory frequency is generally in the range between approximately 400Hz and 800Hz.
  • a driving frequency in this range produces the greatest reduction in tapping torque for a given drive voltage.
  • the illustrated embodiments incorporate a piezoelectric vibratory actuator although other actuators will occur to one of skill in the art and may be applicable to arrangements in accordance with the present invention.
  • a screw vibration assisted tapping device in accordance with the present invention is advantageously compact and includes no moving parts.
  • the simple configuration can be produced using known and well- established manufacturing techniques.
  • the resulting assembly is extremely rugged and should have a long service life when incorporated into tapping equipment.
  • the materials and configuration of the frame may be selected to produce a screw vibration tailored for the threads being tapped.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Turning (AREA)

Abstract

L'invention concerne un dispositif de taraudage à vibration comprenant une structure élastique de translation d'une vibration axiale en une vibration à composante axiale et de torsion. La structure élastique comprend des éléments de flexion connectant une plaque supérieure à une plaque inférieure, un actionneur vibratoire étant préchargé entre celles-ci. Les éléments de flexion sont inclinés par rapport à un axe de la structure dans une direction calculée de manière à obtenir une vibration de translation sensiblement alignée avec l'angle avant du filet coupé. L'invention concerne également un système automatique d'application de différents modèles de vibration sur l'interface taraud/pièce au cours du taraudage, et d'enregistrement du couple de taraudage associé à chaque modèle de vibration. Le système de l'invention permet d'identifier la fréquence et l'amplitude de vibration permettant d'obtenir la plus grande réduction du couple de taraudage. Ce système automatique peut être configuré comme une machine-outil adaptative destinée à identifier puis à appliquer le modèle de vibration optimal.
PCT/US2003/039157 2002-12-12 2003-12-10 Dispositif de taraudage a vibration WO2004054747A2 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU2003293471A AU2003293471A1 (en) 2002-12-12 2003-12-10 Screw vibration assisted tapping device

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US43283702P 2002-12-12 2002-12-12
US60/432,837 2002-12-12

Publications (2)

Publication Number Publication Date
WO2004054747A2 true WO2004054747A2 (fr) 2004-07-01
WO2004054747A3 WO2004054747A3 (fr) 2004-11-25

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US (1) US20040121848A1 (fr)
AU (1) AU2003293471A1 (fr)
WO (1) WO2004054747A2 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107214384A (zh) * 2017-08-04 2017-09-29 安徽六方重联机械股份有限公司 一种用于内六角螺栓的套丝设备

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2901163B1 (fr) * 2006-05-17 2009-01-23 Aeds Ccr Dispositif de percage a vibrations axiales auto-entretenues
US8112870B2 (en) 2007-11-19 2012-02-14 Medical Facets Llc Bone screw and method for manufacturing the same
US8535358B2 (en) 2007-11-19 2013-09-17 Medical Facets, Llc Bone screw and method for manufacturing the same

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1061374A (en) * 1963-02-20 1967-03-08 Adolf Roebig Drive means for rotary cutting tools
US4419912A (en) * 1980-06-24 1983-12-13 Pilot Man-Nen-Hitsu Kabushiki Kaisha Vibration threading lathe for precision screw cutting

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0253517A (ja) * 1988-08-19 1990-02-22 Junichiro Kumabe 断続パルス切削力波形の超音波振動と低周波振動の重畳振動によるねじ溝加工方法及び装置
JPH0253519A (ja) * 1988-08-19 1990-02-22 Junichiro Kumabe 断続パルス切削力波形の超音波振動によるねじ溝加工方法及び装置
JPH0253518A (ja) * 1988-08-19 1990-02-22 Junichiro Kumabe 断続パルス切削力波形の超音波振動と低周波振動によるねじ溝加工方法及び装置

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1061374A (en) * 1963-02-20 1967-03-08 Adolf Roebig Drive means for rotary cutting tools
US4419912A (en) * 1980-06-24 1983-12-13 Pilot Man-Nen-Hitsu Kabushiki Kaisha Vibration threading lathe for precision screw cutting

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 014, no. 221 (M-0971), 10 May 1990 (1990-05-10) & JP 02 053517 A (JUNICHIRO KUMABE), 22 February 1990 (1990-02-22) *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107214384A (zh) * 2017-08-04 2017-09-29 安徽六方重联机械股份有限公司 一种用于内六角螺栓的套丝设备

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WO2004054747A3 (fr) 2004-11-25
AU2003293471A1 (en) 2004-07-09
US20040121848A1 (en) 2004-06-24

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