MXPA99009926A - Double-shell closure having an arcuate groove - Google Patents

Abstract

A closure is provided having concentric inner and outer spaced cylindrical shells attached at respective first distal ends thereof by a circular top wall. An arcuate groove is provided in an upper surface of the top wall integral with the inner cylindrical shell.

Description

TORQUE APPLICATOR TOOL WITH BASE IN A RESONANT AND OSCILLATING MASS BACKGROUND OF THE INVENTION The invention relates in general to energized tools, in particular, with torque-applying tools of the type which are held by hand and which are based on the principle of inertia. Currently, low reaction tools are typically devices that accelerate a rotary inertial mass through a relatively large travel angle. This acceleration is developed using a motor with a torque output that is relatively low compared to the torque output capacity of the tool. As the inertial mass accelerates, it stores kinetic energy. After the inertial mass travels through an important angle (e.g., 180 degrees or more), a clutch means engages the rotating inertial mass with a workpiece. The subsequent negative acceleration of the inertial mass results in a torque output that is relatively high compared to that provided by the acceleration motor (see Figure 3). This high torque output does not produce any reaction on the user since the reaction is provided by the torque associated with the negative acceleration of the inertial mass or flywheel.

Typically, two types of clutch means are provided between the inertial mass and the work piece. The dominant method is the use of a mechanical clutch. The rapid coupling and uncoupling of the clutch unfortunately causes the production of noise and high stresses that develop in the area of impact conversion of the clutch, causing wear and deformation of the parts which reduces efficiency and limits the life of the clutch. A second clutch method uses a hydraulic locking clutch. Although it is quieter in operation compared to existing mechanical clutches, the manufacturing cost and the potential loss of hydraulic fluids limit their application. The closest prior art is Japanese Patent JP-A-04030974 which discloses an energized screw driving device wherein a high frequency current is used together with a stirring body to generate a fine vibration which is transmitted through the tip of the screw. The vibratory action effects a knocking against the screw, while it is being tightened in order to improve the operation of the screwdriver. While the vibratory action of the agitator body can help the operation of the screwdriver, the vibratory force is small and inadequate to overcome the AMENDED SHEET friction required by torque-based tools based on inertia, of the type that are held by hand.

The above illustrates the limitations that are known to exist in current devices and methods. Therefore, it is evident that it would be advantageous to provide an alternative aimed at solving one or more of the limitations set forth above. Accordingly, a suitable alternative is provided which includes features that will be more fully set forth below. SUMMARY OF THE INVENTION In an aspect of the present invention, the above is achieved by providing a torque applicator tool that operates on a resonant and oscillating mass and includes a rotating, resonant and oscillating mass; a means to effect the oscillation of the mass; a spring means connecting the oscillating mass to a rotating workpiece fixed by friction; means for effecting a rotational thrust with the oscillating mass in a rotational tightening direction of a sufficient magnitude only in combination with a force generated by the oscillating mass in the same rotational tightening direction to rotate the workpiece in a direction Of tightening; and a force generated by an oscillating mass in a AMENDED SHEET the rotational direction opposite to that which is subtracted from the rotational thrust, said force being insufficient to effect the rotation of the workpiece in the opposite rotational direction.

These aspects and others will become apparent with the following detailed description of the invention, when considered together with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a cross-sectional view of a torque applicator tool based on a resonant and oscillating mass, according to the invention; Figure 2 is a graph showing the application of torque on a fastener, in the course of time, for an impact tool operating on the basis of an accelerated mass, according to the prior art; and Figure 3 is a graph showing the torque applied to a fastener, in the course of time, for a system tool based on a resonant and oscillating mass, according to the present invention. DETAILED DESCRIPTION OF THE INVENTION Referring to Figure 1 there is shown a torque applicator tool based on a IMMEDIATE LEAF resonant and oscillating mass of the present invention and, in general, is designated by the reference numeral 1. A nozzle-like fastening means or receptacle 5 strongly engages the head of a fastener to be tightened (not shown). The nozzle-type receptacle 5 is connected to a torsion spring 3 which is, in turn, connected to a cup-shaped flywheel motor or oscillating mass 4. The flywheel rotor 4 oscillates and rotates around an internal stator 20 in the way that will be described later. A permanent magnet 9 is housed within a groove 2 within the inner diameter of the flywheel rotor 4. A magnetic return path 8 and protective ring surrounds the flywheel rotor 4 and is made of a magnetically conductive material, for example steel. The protective ring 8 in turn is enclosed in a box 15 that forms the outer shell of the tool. A handle 11 is provided attached to the box 15 in order to hold the tool. A trigger 14 activates the tool and a forward and reverse switch 13 selects the direction of rotation between a direction of tightening (usually clockwise) and a direction of loosening or unscrewing (usually left-handed) according to the position of the operator. As shown in Figure 1, the flywheel rotor 4, the torsion spring 3 and the nozzle 5 are hinged to be able to rotate inside the ROOM AMENDED housing 15 by means of a bearing 16 and within an extension of the stator 20, by means of the bearings 17 and 18 that surround the nozzle 19. A front optical encoder 7 is provided to monitor the rotation of the nozzle and a optical encoder 10 for the position of the flywheel, in order to determine the movement and position of the rotor 4 of the flywheel. In operation, when tightening a threaded fastener, the flywheel is initially driven as a conventional motor by means of the excitation of electromagnetic coils 6 and the reaction against the permanent magnets 9, to effect the attack portion of a tightening cycle. Once the fastener reaches the output limit of the flywheel being driven as a conventional motor, rotation of the nozzle-type receptacle 5 ceases, according to what the front optical encoder 7 detects. The position of the flywheel 4 is detected by the optical position encoder 10. As illustrated in Figure 3, upon detecting the condition of a clogged nozzle, suitable electrical circuitry initiates the oscillatory motion of the flywheel by applying inverse energy pulses to the electromagnetic coils 6, causing the flywheel to oscillate at or near the resonant frequency of the inertial mass spring system. The steering wheel is continuously pushed in the direction of tightening to AMENDED SHEET as the pulse oscillation continues to accumulate and store oscillation energy in the reverse directions, in the torsion spring 3. This establishes a condition in which the oscillating energy plus the energy driven by the motor are added to apply a tightening torque on the fastener in an oscillating direction of the steering wheel and subtracted by applying an inverse oscillation, so that the tightening torque exceeds the loosening torque by an amount approximately equal to twice the thrust torque. As the energy stored in each inverse pulse increases due to the resonant condition, or close to the resonant, of the mass spring system, it reaches a point at which the applied sum of the torques continues to act on the tightening of the fastener without a corresponding loosening in the reverse oscillation. It has been found that a driven torque of approximately 10 to 20 percent of the final output torque of the tool is required to prevent reverse oscillation from loosening the fastener element. This value of the driven torque is received as a reaction by the operator. Therefore, by using the oscillating mass that is the main feature of this invention, it is possible to achieve output torques whose magnitude is many times greater than the torque with which the operator reacts. Other AMENDED SHEET The way to establish this is that when the torque in the torsion spring exceeds the torque of the work piece that resists the movement of the fastener element, the fastener would be accelerated by the difference between the torques. In this process, some of the energy would be removed from the oscillating mass system. The motor would replace this energy and add more energy with repeated oscillation to allow the oscillation to continue to accumulate. When the desired torque for the fastener has been reached, the engine will cease to excite the steering wheel. The optical encoders 10 and 7 provide feedback for the control of the tool. As noted, to prevent the fastener from loosening, the oscillating excitation torque would be imposed on the top of a thrust torque or a motor-driven torque. This thrust torque would be a fraction of the torque that is required to tighten the joint. In addition to the aforementioned modalities, several other modalities are possible. In some cases, the oscillating mass may be attached to the workpiece as in the present embodiment. In other cases, a clutch means may be used to drive the torque applied to the workpiece after a certain level of kinetic energy has been stored in the oscillating mass. The common factor of all modalities is that the energy that It will be used to apply torque to the work piece by oscillating a mass spring system at or near its resonant frequency. The benefits of a tool that is based on this concept include obtaining a low-weight tool. Current tools require a sufficiently large combination of motor / inertia to develop sufficient kinetic energy to overcome the current torque level of the workpiece while accelerating inertia through the limited travel angle. In the present invention, by continuing the application of the excitation for a longer time, a greater torque amplitude can be achieved without increasing the size of the motor or inertia. The tool of the present invention exhibits little counter-reaction and little vibration. The excitation frequencies can, in general, be high in relation to the torque supply frequency for the current tools. These higher frequencies can be attenuated more easily than the frequencies associated with "repeated steering spin" in current tools (see Figure 2). In approaches that are made based on oscillating mass and that use narrow band excitation frequencies, it is easier to implement vibration and sound reduction strategies, in comparison with instrumentations that are made for the broadband behavior of current impact tools. In addition, impact surfaces can be removed resulting in less noise and less wear. The tools according to the invention are easier to control and exhibit greater torque accuracy. The tools of the current modalities provide torque to the workpiece in more frequent and smaller torque impulses. Smaller pulses allow finer control over the applied torque and are less dependent on the rigidity of the work piece, ie, classification of the joint with respect to current low reaction tools. In addition, the concept of the present leads directly to modalities driven in electronic form that provide greater control for the user in other ways, for example, in the speed of operation. Having described the invention in terms of the preferred embodiment, we do not wish to limit the scope thereof, with the exception of what is claimed below.

Claims (6)

1. CLAIMS: 1. A torque applying tool based on an oscillating and resonant mass that is used with a rotating workpiece, fixed by friction, comprising: a mass rotatably resonant and rotationally oscillating (4); a means to effect the resonant oscillation of the mass; a spring means (3) connecting the oscillating mass with a rotating workpiece fixed by friction, the spring means allows relative rotation between the rotatably resonant and rotationally oscillating mass and the rotating workpiece, fixed by friction; means for effecting a rotational thrust with the oscillating mass in a rotational tightening direction of a sufficient magnitude only in combination with a force generated by the oscillating mass, in the same rotational tightening direction, to rotate the workpiece in a tightening direction; and a force generated by the oscillating mass in a rotational direction opposite to that which is subtracted from the rotational thrust, said force being insufficient to effect the rotation of the workpiece in the opposite rotational direction. 2. A torque applicator tool that
2. ROOM AMENDED it operates on the basis of an oscillating and resonant mass according to claim 1, wherein the torque applicator tool (1) comprises a manual torque wrench.
3. 3. A torque applicator tool operating on an oscillating and resonant mass according to claim 1, wherein the spring means (3) comprises a torsion spring.
4. 4. A torque applicator tool based on an oscillating and resonant mass according to claim 1, wherein the means for effecting a rotational thrust applies the torque in the direction of rotation, in a magnitude of approximately 10 to 20 percent of a torque of final output.
5. 5. A torque applicator tool based on an oscillating and resonant mass according to claim 1, wherein the position of the oscillating mass (4) is determined by a position encoder (10).
6. 6. A torque applicator tool based on an oscillating and resonant mass according to claim 5, wherein the position encoder (10) comprises an optical position encoder. SHEET ENMiNPA A