WO1989003278A1

WO1989003278A1 - Ultrasonic tool support

Info

Publication number: WO1989003278A1
Application number: PCT/US1988/003533
Authority: WO
Inventors: James R. Gilmore
Original assignee: Extrude Hone Corporation
Priority date: 1987-10-13
Filing date: 1988-10-13
Publication date: 1989-04-20
Also published as: AU2607188A

Abstract

A tool support structure for an abrading tool in an ultrasonic machining tool which consists of a sleeve member (32) attached to a tool assembly support structure (18) at a node point on the assembly and extending along the sonotrode (16) without contact therewith to the working end of the sonotrode (16), and having a plurality of lateral support members (34) connected at one end to said sleeve member (32) and the other end removably connected to the end of said sonotrode (16). Said sleeve member (32) is further provided with a hole (36) near the bottom thereof adjacent to the tool assembly support structure (18) to permit drainage of any slurry which may fall between the sleeve structure (32) and the sonotrode (16).

Description

WO 89/03278 —^~\— PCT/US88/03533

ULTRASONIC TOOL SUPPORT

TECHNICAL FIELD

This invention relates generally to ultrasonic machine tools. More specifically, this invention relates to a support structure for minimizing the lateral movement of an ultrasonic tool during ultrasonic machining to enhance the quality of work.

BACKGROUND ART

Ultrasonic machining is a well known machining process whereby the surface of a workpiece is abraded by a grit contained in a slurry circulated between the workpiece surface and a vibrating tool adjacent thereto, vibrating at frequencies above the audible range, i.e. typically within the range 19,500 to 20,500 cycles per second. The abrading tool face is usually provided with a three-dimensional form, while a negative compliment thereof is machined onto the workpiece surface. This process finds particular utility in its ability to work difficult materials, such as glass, ceramics, calcined or vitrified refractory materials and hard and/or brittle metals, which are not susceptible to machining by any other traditional technique, or even such nontraditional techniques such as electrical discharge machining, electro-chemical machining or the like.

While ultrasonic machining is capable of producing a moderately good degree of accuracy, its use is usually limited to applications requiring only a less than a good degree of detail accuracy because several difficult to control variables can adversely affect dimensional accuracy. The inability to prevent lateral deflection of the abrading tool during operation is a

SUBSTITUTE SHEET major factor which can adversely affect the machining accuracy

Such deflection, is usually caused by the necessarily elongate nature of the abrading tool, in combination with other difficul to control factors such as slight misalignment of the abradin tool on the underlying structure, presence of abrasives or debri on the sides of the abrading tool and the like. The abradin tool itself, referred to in the art as a sonotrode, i necessarily elongated in nature because the tool structure ca only be supported at a node point along the length of th structure which is spaced a good distance away from the workin face of the tool or sonotrode. Because the sonotrode an supporting structure are in constant ultrasonic motion durin operation, it is not practical to provide lateral support betwee the tool and the machine's base structure. The above note limitations have generally resulted in the choice of othe machining techniques when the nature of the material to be worke permits.

DISCLOSURE OF THE INVENTION

This invention is predicated on the development of a to support structure that will provide some degree of later support for the abrading tool, i.e. sonotrode, even duri operation when the sonotrode is in ultrasonic motion. Th support structure will therefore, function to minimize later displacement of the working end of the sonotrode duri operation, and thereby enhance accuracy in the machini operation.

SUBSTITUTE SHEET It is therefore an object of this invention to provide a tool support structure for ultrasonic machining to improve accuracy in the machining operation.

It is another object of this invention to provide a tool support structure for ultrasonic machining which will provide adequate lateral support for the the working end of the sonotrode and yet permit it to move freely in its vertical ultrasonic motion.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is an isometric view of an ultrasonic tool assembly which includes a tool support structure in accordance with a preferred embodiment of this invention.

Figure 2 is a cross sectional side view of the ultrasonic tool assembly shown in Figure 1.

BEST MODE OF CARRYING OUT THE INVENTION

Reference to the figures will illustrate the arrangement of an ultrasonic tool assembly which incorporates one embodiment of this invention. The ultrasonic tool assembly in essence consists of a transducer 10, having a booster 12 secured to the top thereof, and a sonotrode 16 secured to the top of the booster 12. The transducer 10, which uses a stack of piezoelectric ceramic disks (not shown) , is activated by a high frequency power source (not shown) , which will induce a low amplitude, ultrasonic vibration in the stack of disks. The booster 12, having a conical configuration, serves to enhance or suppress the amplitude of the ultrasonic vibrations, so that the vibration amplitude at the small end of the cone can be controlled to that

SUBSTITUTE SHEET desired. Typical, in ultrasonic machine tools, the booster usually doubles the amplitude produced by the transducer. The sonotrode 16 is the abrading tool with the abrading face at the top end of an elongated solid body portion which transmits the ultrasonic vibrations from the end of the booster 12 to the working face at the top of sonotrode 16. Since the vibrational motion must be transmitted from transducer 10 to the abrading face of sonotrode 16 tool through booster 12, these three components must be secured very tightly together. Because all three components are in ultrasonic vibration during operation, it would appear to be difficult if not impossible to secure the structure in a machine tool base. Fortunately, however, there are one or more node points, that is points where there is no vibration, along the alignment of the three components. Accordingly, an assembly support fixture, such as assembly support ring 18, is secured to the assembly at a node point. The assembly support ring 18 is then utilized to secure the assembly to the machine tool's base structure (not shown). A water-tight jacket 20 is provided around transducer 10 which serves not only to maintain circulating cooling air around the transducer 10, but also to protect transducer 10 from any grit or machining debris which will be washed down from the machining operation.

While the above described assembly is common to prior art ultrasonic machine tools, the crux of this invention resides in the tool support structure 30, which serves to support the working end of sonotrode 16 to minimize its lateral deflection from what ever cause. Tool support structure 2SL consists of an

SUBSTITUTE SHEET elongated, rigid sleeve member 32 secured to support ring 18 and extends upwardly therefrom surrounding sonotrode 16 but essentially spaced therefrom so that no portion thereof contacts sonotrode 16. A plurality of lateral braces 34 are disposed between sleeve member 32 and the top, or working end of sonotrode 16. One end of lateral braces 34 are securely attached to, or are a part of sleeve 32, while the other ends thereof are silver soldered near to the top surface or cutting face of sonotrode 16. The base of sleeve ^"member 32 is provided with a plurality of openings 36 so that any slurry falling between sleeve 32 and sonotrode 16 will readily drain away. With the base of sleeve 32 tightly secured to support ring 18, it is apparent that sleeve 32 will not vibrate with the ultrasonic vibrations of the tool assembly. For that reason, sleeve 32 should not contact sonotrode 16 except via braces 34 at the top end of sonotrode 16. Sonotrode 16 will therefore, be free to vibrate ultrasonically with respect to stationary sleeve member 32. Accordingly, lateral braces 34 should be rigid enough to provide adequate lateral support to prevent the top of sonotrode 16 from being deflected laterally, but yet flexible enough to permit repeated vertical deflection of those ends soldered to sonotrode 16. In that way, lateral braces 34 will adequately support the top of sonotrode 16 preventing it from lateral displacement from whatever cause, while at the same time the ends thereof will be flexing up and down at ultrasonic cycles in unison with sonotrode 16.

SUB_STITUTESHEET While the above description is addressed to a preferred embodiment, it is obvious that other embodiments and modifications could be utilized without departing from the spirit of the invention. For example, while sleeve member 32 is shown to be attached to support ring 18, future designs could produce ring 18 and sleeve member 32 as a single structural member. In addition, lateral braces 34 could be provided in a number of different configurations including differing numbers of individual support tabs as shown, or even a solid ring, with its outer periphery attached to sleeve member 32 and the inner periphery attached to the sonotrode 16. The use of individual braces as shown, however, provides the advantage of facilitating assembly and disassembly. In a like manner, any method for attaching lateral braces 34 to abrading tool 16 could be utilized, but silver solder is preferred because it permits disassembly and reassembly of the unit if required.

SUBSTITUTESHEET

Claims

1. A tool support structure for use on an ultrasonic machine tool having a tool assembly consisting at least in part of a sonotrode having an abrading surface at one end with the other end attached to an ultrasonically vibrating device to form an ultrasonic tool assembly, and an assembly support fixture attached to a node point on said assembly, said tool support structure comprising a sleeve member securely attached to said assembly support fixture and extending therefrom to the abrading face of said sonotrode without being in contact with said sonotrode, said sleeve member having an elongated lateral bracing member extending from said sleeve member to the end of said sonotrode, said bracing member being secured to said sonotrode, and being sufficiently rigid to minimize any lateral displacement of said sonotrode while being flexible enough to elastically flex vertically with the sonotrode in its ultrasonic vibration.

2. A tool support structure according to Claim 1 wherein a plurality of said bracing members are provided spaced around the end of said sonotrode.

3. A tool support structure according to Claim 1 wherein said bracing member consists of a horizontally disposed ring with its outer periphery attached to said sleeve member and the inner periphery attached to the end of said sonotrode.

4. A tool support structure according to Claim 1 wherein said bracing member is removably secured to said sonotrode by silver soldering.

SUBSTITUTE SHEET

5. A- tool support structure according to Claim 1 further having an opening in the base of said sleeve member adjacent to said assembly support fixture for the purpose of permitting drainage of any slurry that may fall between said sleeve member and said sonotrode.

SUBSTITUTESHEET