Patent Grant
9789580
(1) Field of the Invention
The present invention relates to a tool unit applied to ultrasonic machining, particular to one that is suitable for ultrasonic machining in micron precision to workpieces made of brittle materials.
(2) Description of the Prior Art
Normally, ultrasonic machining process is used to cut brittle materials. The operation of the ultrasonic machining process is essentially performed by a vibrating tool unit disposed at the front of the ultrasonic machining apparatus, wherein the vibrating tool unit is resonated to oscillate at ultrasonic frequencies produced by an ultrasonic generator.
Following the progressive trend for the science and technology, the miniaturizing requirement of the industrial product becomes inevitable. However, two impending issues in most conventional ultrasonic machining apparatus are urgently needing be solved. Firstly, in a common assembly of the conventional ultrasonic machining apparatus, the machining head of cutting tool is rigidly connected to the ultrasonic amplitude transformer by means of fasteners such as screws or metal buckling rings, which unavoidably creates somewhat irregular gaps scatter along the connecting section between the machining head of cutting tool and ultrasonic amplitude transformer. Accordingly, the machining precision is worsened due to uneven distributions of the vibration amplitude over the machining head of cutting tool so that the machining precision can not be improved up to micron scale still being kept at millimeter scale.
Secondly, the machining head of cutting tool in common assembly of the conventional ultrasonic machining apparatus is made of materials selected from metals or metal alloys, which are always confined to short service life due to susceptible to quickly wearing and damage under the ultrasonic vibration. A common preliminary solution to improve the service life for the machining head of cutting tool is that coating a layer containing diamond or diamond-like materials over the substrate of the cutting tool via plasma-enhanced deposition technique. However, this preliminary solution did not thoroughly solve the drawbacks of the cutting tool because the problematic issue in the connecting section between the machining head of cutting tool and ultrasonic amplitude transformer is still not solved yet. Having realized and addressed foregoing issues, the present invention is worked out to thoroughly solve them without sacrificing the precision level even under harsh machining condition for a long time.
The primary object of the present invention is to provide a tool unit applied to ultrasonic machining in micron precision with features in excellent wearing resistance hardness and optimal assembly configuration for evenly propagating ultrasonic field.
In order to effectively achieve foregoing object aforesaid, the present invention provides a tool unit applied to ultrasonic machining, the tool unit comprises a machining head having an array structure with micron machining precision, an amplitude transformer and a connecting portion. The machining head is a laminated composite of multi-layer materials with mutual matching features in tightly latch each other, disposed beneath of the amplitude transformer. The multi-layer materials include a substrate and a diamond layer. The substrate has an upper surface and a lower surface located at two opposite sides of the substrate, wherein the material of the substrate is selected from a group consisting of a steel with thermal expansion coefficient in range from 10.70×10−6K−1 to 17.30×10-6K−1, tungsten carbide and a combination thereof. The diamond layer comprises a material selected from a group consisting of a diamond material with thermal expansion coefficient in range from 1.00×10−6K−1 to 2.50×10−6K−1, a polycrystalline diamond, a diamond sinter and a combination thereof. The connecting portion is sandwiched between the amplitude transformer and the machining head, wherein the shape of the connecting portion is different between before and after forming an assembly of the amplitude transformer, the connecting portion and the machining head.
In an exemplary preferred embodiment of the present invention, the machining head comprises a surface working layer, the surface working layer and the substrate are disposed at two opposite sides of the diamond layer, the material of the substrate is the steel with thermal expansion coefficient in range from 10.70×10−6K−1 to 17.30×10−6K−1; the diamond layer comprises a layer of plural electrophoretic deposited diamond particles with thermal expansion coefficient in range from 1.00×10−6K−1 to 2.50×10−6K−1 embedded in an electrophoretic deposited metal bed layer with thermal expansion coefficient in range from 4.80×10−6K−1 to 13.80×10−6K−1; and the surface working layer is a non-metal coating with thermal expansion coefficient in range from 1.00×10−6K−1 to 13.80×10−6K−1 and density thereof is greater than that of the electrophoretic deposited diamond layer.
In an exemplary preferred embodiment of the present invention, the material for the electrophoretic deposited metal bed layer is selected from one of a group consisting of nickel, cobalt and molybdenum.
In an exemplary preferred embodiment of the present invention, the material for the surface working layer of the tool unit is selected from group of diamond, titanium carbide or composite of any combination from foregoing materials. Moreover, a metal buffer layer is further sandwiched between the diamond layer and the surface working layer such that the material thereof is selected from group of nickel, titanium, aluminum and composite of any combination from foregoing materials.
In an exemplary preferred embodiment of the present invention, the material of the substrate is tungsten carbide, and the diamond layer comprises ingredients of a diamond sinter and a sintering accelerant such that the weight percentage for the diamond sinter exceeds over 85% while the weight percentage for the sintering accelerant is less than 15%, wherein the diamond sinter is a sinter of polycrystalline diamonds while the sintering accelerant is selected from a group consisting of iron, cobalt, nickel and a combination thereof.
In an exemplary preferred embodiment of the present invention, the material of said amplitude transformer in the tool unit is selected from group of steel, stainless steel, aluminum alloy, magnesium alloy, titanium alloy and composite of any combination from foregoing materials.
In an exemplary preferred embodiment of the present invention, the material of said amplitude transformer in the tool unit is steel while the material of the connecting portion includes brazing material, which can be selected from group of eutectic mixture of metal alloys including Ag—Cu, Ag—Al, Ag—Mg, Al—Cu, Al—Mg, Cu—Mg and composite of any combination from foregoing materials. Moreover, a brazing additive is doped in the brazing material such that the brazing additive is one of silicon and titanium. Or, the material of the connecting portion includes a composite brazing material composed of alloy with Ag, Cu, Mg, Al, Si and Ti, whose weight percentage for each specific constituent is listed as following: the weight percentage of the constituent Ag is in range from 10% to 50%, the weight percentage of the constituent Cu is in range from 10% to 50%, the weight percentage of the constituent Mg is in range from 0% to 40%, the weight percentage of the constituent Al is in range from 0% to 40%, the weight percentage of the constituent Si is in range from 0% to 20%, and the weight percentage of the constituent Ti is in range from 0% to 20%.
In an exemplary preferred embodiment of the present invention, the material of said connecting portion is suitable for brazing process with brazing temperature being preferably in range from 600 to 650 centigrade degree to create an intermetallic compound with promoted brazing strength in a range from 600 kg/mm2 to 800 kg/mm2 such that the material of the intermetallic compound is selected from group of Ag, Ag3Fe2, FeCu4, Cu4W6, Al4Si, Mg2Si, Mg5Si6, Mg2Al3, MgAl2, MgAl, Mg2Al3, Al2W, Al5W, Al4W, FeSi, AlFe, AlFe3, TiC and FeTi.
In an exemplary preferred embodiment of the present invention, said machining head includes a columnar cavity created therein with an inner diameter, and said connecting portion, which has an outer diameter, includes a frustum hole created therein with a second bottom inner diameter, as well as said amplitude transformer includes a frustum protrusion created thereon with a first bottom outer diameter such that the first bottom outer diameter of the frustum protrusion is slightly greater than the second bottom inner diameter of the corresponding frustum hole while the outer diameter of the connecting portion is slightly less than the inner diameter of the corresponding machining head before the assembly of the amplitude transformer, connecting portion and machining head; and wherein the taper for the frustum hole of the connecting portion is the same as the taper for the corresponding frustum protrusion of the amplitude transformer so that the frustum hole can snugly accommodate the frustum protrusion; and during assembly, the frustum protrusion of the amplitude transformer is firstly inserted into the frustum hole of the connecting portion with interference fit happened between the frustum hole of the connecting portion and the corresponding frustum protrusion of the amplitude transformer, meanwhile the outer diameter of the connecting portion is dilated to become that the outer diameter of the connecting portion is slightly greater than the inner diameter of the columnar cavity of the corresponding machining head for another interference fit happened between the connecting portion and the columnar cavity of the corresponding machining head.
In an exemplary preferred embodiment of the present invention, said tool unit is adapted with following modifications that the columnar protrusion of amplitude transformer is converted into a columnar cavity of amplitude transformer while the columnar cavity of machining head is converted into a columnar protrusion of machining head. Thus, the columnar cavity of the amplitude transformer is suitable for the connecting portion placed therein, and the connecting portion has a hole, the columnar protrusion of machining head is located on the upper surface of the substrate, for inserting into the hole of the connecting portion to contact the amplitude transformer.
In an exemplary preferred embodiment of the present invention, the material of said connecting portion includes a shape memory alloy (SMA) with transition temperature in range from 180 to 100 degrees centigrade.
In an exemplary preferred embodiment of the present invention, the constructing material of said connecting portion is a metal with thermal expansion coefficient in range from 10.7×10−6K−1 to 19.00×10−6K−1 while respective thermal expansion coefficient for amplitude transformer, connecting portion and substrate of the machining head is different each other.
As shown in all exemplary preferred embodiments of the present invention, other than meticulous versatility of the connecting section between the machining head of cutting tool and ultrasonic amplitude transformer, the machining head of the tool unit is bolstered by enveloping laminate of multi-layer with diamond of the present invention provides multiple supporting means in the foundation layer, lining layer, buffer layer and working layer respectively so that the present invention is suitably used in ultrasonic machining with micron precision to complicated workpiece under harsh machining conditions for long period due to intrinsic durable features in wearing-resistance and anti-fatigue properties.
Regarding technical contents, features and effects disclosed above and other technical contents, features and effects of the present invention will be clearly presented and manifested In the following detailed description of the exemplary preferred embodiments with reference to the accompanying drawings which form a part hereof. In this regard, directional terminology such as “top,” “bottom,” “front,” “back,” etc., is used with reference to the orientation of the Figure(s) being described. The components of the present invention can be positioned in a number of different orientations. As such, the directional terminology is used for purposes of illustration and is in no way limiting.
Regarding the selection of suitable material for respective machining head 21, amplitude transformer 22 and connecting portion 23 is in the preferred exemplary embodiment of the present invention, it can summarized as that for amplitude transformer 22, there are two options of light alloys and steels; for connecting portion 23 of flexible layer, there are two alternatives depending on the material used by the amplitude transformer 22 for optimal engagement; and for machining head 21 of laminated composite, there are many discretions with adaptability for best compatibility with amplitude transformer 22 and connecting portion 23. Specifically, the material for amplitude transformer 22 can be selected from light alloys or steels such as steel with thermal expansion coefficient in range from 11.00×10−6K−1 to 13.00×10−6K−1; stainless steel with thermal expansion coefficient in range from 10.70×10−6K−1 to 17.30×10−6K−1; aluminum alloy with thermal expansion coefficient in range from 21.00×10−6K−1 to 25.00×10−6K−1; magnesium alloy with thermal expansion coefficient in range from 25.00×10−6K−1 to 28.00×10−6K−1; titanium alloy with thermal expansion coefficient in range from 9.00×10−6K−1 to 13.00×10−6K−1; or composite of any combination from foregoing materials with thermal expansion coefficient in range from 9.00×10−6K−1 to 28.00×10−6K−1. For two alternatives in the connecting portion 23 of flexible layer in accordance with the material used by the amplitude transformer 22 for optimal engagement, In status A, if light alloy is adopted by the amplitude transformer 22, an “interference fit” is suitable for firmly cemented bonding between the machining head 21 and the connecting portion 23. Whereas in status B, if steel is adopted by the amplitude transformer 22, a “brazing process”, which converts the connecting portion 23 into an intermetallic compound, is suitable for firmly cemented bonding among the machining head 21, connecting portion 23 and amplitude transformer 22. In general, the shape of the connecting portion 23 is changed by the “interference fit” or the “brazing process”, and different between before and after firmly bonding the amplitude transformer 22 to the connecting portion 23 and the machining head 21.
Regarding of the machining head 21, two exemplary preferred embodiments rendered in
In practical fabrication of the machining head 21A in this exemplary preferred embodiment, firstly, the substrate 211A is configured into various protrusions of micron scale disposed such as columnar protrusion 2111 and frustum protrusion 2112 shown in
During final processing step for covering the working layer 215 of diamond coating over the metal cushion layer 214 in foregoing fabrication, carbide like titanium carbide (TiC) may be created therein due to internal chemical reaction. The titanium carbide (TiC), which features in good hardness and strength with thermal expansion coefficient in range from 7.70×10−6K−1 to 13.50×10−6K−1, can be not only served as good bonding interface media but also used as backing material for the working layer 215 of diamond coating. Accordingly, the working layer 215 of diamond coating may comprise a combination of diamond and carbide, and has a thermal expansion coefficient in range from 1.00×10−6K−1 to 13.50×10−6K−1.
Comparing the machining head 21 bolstered by enveloping laminate of multi-layer with diamond aforesaid of the present invention to the corresponding prior art that coating a layer containing diamond or diamond-like materials over the substrate of the cutting tool via plasma-enhanced deposition technique, some advantages and disadvantages are contrasted as following. The prior art did not provide any supporting means for the machining head of cutting tool owing to neglecting the connection features and lattice matching between the layers with diamond and the substrate, and neglecting connecting section between the machining head of cutting tool and ultrasonic amplitude transformer such as latching compatibility and mechanic fit between different materials. Conversely, taking the connecting section between the machining head of cutting tool and ultrasonic amplitude transformer into meticulous consideration, the machining head 21 bolstered by enveloping laminate of multi-layer with diamond of the present invention provides multiple supporting means in the substrate 211A, lining layer 213, buffer layer 214 and working layer 215 respectively so that it is suitably used in ultrasonic machining with micron precision to complicated workpiece under harsh machining conditions for long period due to intrinsic durable features in wearing-resistance and anti-fatigue properties.
Regarding the firmly cemented bonding means among key components of the amplitude transformer 22, connecting portion 23 and machining head 21 of the tool unit 2, please refer to
The firmly cemented bonding means can be classified into following categories.
Category 1: The firmly cemented bonding means is achieved by mechanical interface fit.
There are three subcategories, which are respectively illustrated in
Subcategory 1-1: there are three statuses as below.
Status A is described in paragraphs in association with
Status B is described in paragraphs in association with
Status C is described in paragraphs in association with
Subcategory 1-2: The firmly cemented bonding means is achieved by features of shape memory alloy (SMA), which is described in paragraphs in association with
Subcategory 1-3: The firmly cemented bonding means is achieved by thermal expansion coefficient of material, which is described in paragraphs in association with
Category 2: The firmly cemented bonding means by metalworking brazing process, which is described in below paragraphs.
For status A in subcategory 1-1 of the category 1, wherein the firmly cemented bonding means is achieved by mechanical interface fit,
For subcategory 1-2 of the category 1, wherein the firmly cemented bonding means is achieved by features of shape memory alloy (SMA),
For subcategory 1-3 of the category 1, wherein the firmly cemented bonding means is achieved by thermal expansion coefficient of material,
By exploiting the difference in the thermal expansion coefficient (TEC), the materials for key components of the can be selected as that the thermal expansion coefficient (TEC) of the amplitude transformer 22a is larger than that of the connecting portion 23a while the thermal expansion coefficient (TEC) of the connecting portion 23a is larger than that of the machining head 21a, then metalworking process them into desired shapes and assemble them under low temperature like 5 centigrade degree so that the firmly cemented bonding for the amplitude transformer 22a, connecting portion 23a and machining head 21a of the tool unit 2a can be achieved by respective expanding stress between each boundary of different materials at normal room temperature like 25 centigrade degree. Thereby, under working temperature like 45 centigrade degree, the firmly cemented bonding for the amplitude transformer 22a, connecting portion 23a and machining head 21a of the tool unit 2a can be enhanced.
For status B in subcategory 1-1 of the category 1, wherein the firmly cemented bonding means is achieved by mechanical interface fit,
For status C in subcategory 1-1 of the category 1, wherein the firmly cemented bonding means is achieved by mechanical interface fit,
In practical assembly procedure for the tool unit 2c, all the steps are the same as those described in previous paragraphs in association with
Similarly, the alternative cemented bonding means classified as subcategory 1-2, wherein the cemented bonding means is achieved by features of shape memory alloy (SMA) described in paragraphs in association with
In conclusion all disclosure about the mechanical interference fit among the machining head 21, amplitude transformer 22 and connecting portion 23 heretofore of the present invention, comparing to the rigidly connecting means of fasteners such as screws or metal buckling rings used in the conventional ultrasonic machining apparatus, it is apparent that the mechanical interference fit of the present invention is better suitably used in ultrasonic machining with micron precision to complicated workpiece under harsh machining conditions for long period due to intrinsic durable features in wearing-resistance and anti-fatigue properties.
Please refer to
Here, the material of the amplitude transformer 22 is steel while the material of the connecting portion 23 includes brazing material for firmly cemented bonding the machining head 21 and amplitude transformer 22 into an integral tool. In practical application, the material of the amplitude transformer 22 is stainless steel with melting point at about 1500 centigrade degree, the material for the substrate 211 of the machining head 21 is tungsten carbide with melting point at about 2870 centigrade degree, and the material of the connecting portion 23 includes brazing material as mentioned above. Under brazing temperature about 700 centigrade degree, an intermetallic compound will be created between the machining head 21 and connecting portion 23, so that the bonding effect among the machining head 21, connecting portion 23 and amplitude transformer 22 can be successfully achieved and enhanced.
More precisely, normal brazing temperature is over 450 centigrade degree. In the exemplary preferred embodiment of the present invention, certain diamond is embedded in the tool unit 2, which will be overheated and catalyzed into other carbon allotrope such as graphite if brazing temperature is over 700 centigrade degree. Accordingly, the suitable brazing temperature is preferably in range from 600 to 650 centigrade degree. According to technology of the eutectic system, a eutectic solid mixture of metal alloy can be converted into a eutectic liquid mixture if being heated up to over the eutectic temperature, wherein the eutectic liquid mixture is also called as “eutectic solder”, which implies that it can be used as a good bonding media. In 1967, Schulze defined intermetallic compounds as solid phases containing two or more metallic elements, with optionally one or more non-metallic elements, whose crystal structure differs from that of the other constituents. If the material of the connecting portion 23 is an alloy selected from alloy group containing silver, copper, magnesium, silicon and titanium, proper brazing process for cemented bonding among the machining head 21, connecting portion 23 and amplitude transformer 22 can be successfully achieved and enhanced via an intermetallic compound being created therein. Therefore, the material of the connecting portion 23 can be selected from following eutectic mixture of metal alloys, which is also called as “eutectic solder”, such as Ag—Cu with thermal expansion coefficient in range from 17.00×10−6K−1 to 18.00×10−1K−1, eutectic temperature at 780 centigrade degree; Ag—Al with thermal expansion coefficient in range from 19.00×10−6K−1 to 23.00×10−6K−1, eutectic temperature in range from 567 to 726 centigrade degree; Ag—Mg with thermal expansion coefficient in range from 19.00×10−6K−1 to 25.00×10−6K−1, eutectic temperature in range from 492 to 756 centigrade degree; Al—Cu with thermal expansion coefficient in range from 17.00×10−6K−1 to 23.00×10−6K−1, eutectic temperature in range from 547 to 596 centigrade degree; Al—Mg with thermal expansion coefficient in range from 23.00×10−6K−1 to 25.00×10−6K−1, eutectic temperature at 459 centigrade degree; Cu—Mg with thermal expansion coefficient in range from 17.00×10−6K−1 to 25.00×10−6K−1, eutectic temperature in range from 570 to 797 centigrade degree; or composite of any combination from foregoing materials with thermal expansion coefficient in range from 17.00×10−6K−1 to 25.00×10−6K−1, eutectic temperature in range from 492 to 780 centigrade degree. Moreover, a brazing additive such as silicon or titanium can also be doped in the foregoing eutectic mixture of metal alloys for enhancing bonding strength.
In a composite brazing material of the connecting portion 23 comprising alloy with Ag, Cu, Mg, Al, Si and Ti, the weight percentage for each specific constituent metal is listed as following: the weight percentage of the constituent Ag is in range from 10% to 50%, the weight percentage of the constituent Cu is in range from 10% to 50%, the weight percentage of the constituent Mg is in range from 0% to 40%, the weight percentage of the constituent Al is in range from 0% to 40%, the weight percentage of the constituent Si is in range from 0% to 20%, and the weight percentage of the constituent Ti is in range from 0% to 20%. In summary, the overall eutectic temperature for all constituting materials of the connecting portion 23 aforesaid covering Ag, Cu, Mg, Al, Si and Ti, is in range from 459 to 638 centigrade degree. The intermetallic compound may include Ag, Ag3Fe2, FeCu4, Cu4W6, Al4Si, Mg2Si, Mg5Si6, Mg2Al3, MgAl2, MgAl, Mg2Al3, Al2W, Al5W, Al4W, FeSi, AlFe, AlFe3, TiC and FeTi. With such brazing conditions aforesaid, the brazing strength can be promoted to a range from 600 kg/mm2 to 800 kg/mm2 so that all three key components the machining head 21, connecting portion 23 and amplitude transformer 22 for the tool unit 2 can be brazed into an integral cemented ultrasonic cutting tool with such brazing strength. Thus, by means of the cemented bonding of the brazing metalwork, the tool unit 2 of the present invention not only expedites the ultrasonic propagation but also enhances the evenness for the distributions of the ultrasonic amplitude with result that the ultrasonic machining can be easily performed with micron precision.
In conclusion of foregoing disclosure for all exemplary preferred embodiments of the present invention heretofore, the tool unit 2 comprises key components of a machining head 21 with micron machining precision, an amplitude transformer 22 and a connecting portion 23, wherein said amplitude transformer 22 is securely disposed in the ultrasonic machining apparatus 1; said machining head 21, which is a laminated composite of multi-layer materials with mutual matching features in tightly latch each other, disposed beneath of the amplitude transformer 22; and said connecting portion 23 serves as a flexible interface layer of engaging media for the amplitude transformer 22 and machining head 21 so that the machining head 21, amplitude transformer 22 and connecting portion 23 are rigidly cemented into an integral tool unit 2; as well as each specific material for respective machining head 21, amplitude transformer 22 and connecting portion 23 is meticulously selected to have compatibility for reinforcement of mutual engagement and enhancement of ultrasonic energy transmission. The machining head 21 of the tool unit 2 includes a substrate 211 and a lining layer 213, wherein the material of said substrate 211 is selected from group of steel, tungsten carbide and their composite with thermal expansion coefficient in range from 10.70×10−6K−1 to 17.30×10−6K−1 while said lining layer 213 is a diamond layer, whose material is selected from group of polycrystalline diamond, diamond sinter and their composite with thermal expansion coefficient in range from 1.00×10−6K−1 to 2.50×10−6K−1.
With foregoing assembly configurations of a tool unit 2 of the present invention disclosed heretofore, when it is installed in an ultrasonic machining apparatus 1, it is indeed suitable for ultrasonic machining in micron precision to brittle workpiece made of materials such as ceramic, glass, silicon substrate, and silicon carbide, sapphire and so on with features of excellent wearing-resistance and anti-fatigue effects for long duration in ultrasonic machining.
The foregoing description of the preferred embodiment of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form or to exemplary embodiments disclosed. Accordingly, the foregoing description should be regarded as illustrative rather than restrictive. Obviously, many modifications and variations will be apparent to practitioners skilled in this art. The embodiments are chosen and described in order to best explain the principles of the invention and its best mode practical application, thereby to enable persons skilled in the art to understand the invention for various embodiments and with various modifications as are suited to the particular use or implementation contemplated. It is intended that the scope of the invention be defined by the claims appended hereto and their equivalents in which all terms are meant in their broadest reasonable sense unless otherwise indicated. Therefore, the term “the invention”, “the present invention” or the like is not necessary limited the claim scope to a specific embodiment, and the reference to particularly preferred exemplary embodiments of the invention does not imply a limitation on the invention, and no such limitation is to be inferred. The invention is limited only by the spirit and scope of the appended claims. The abstract of the disclosure is provided to comply with the rules requiring an abstract, which will allow a searcher to quickly ascertain the subject matter of the technical disclosure of any patent issued from this disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. Any advantages and benefits described may not apply to all embodiments of the invention. It should be appreciated that variations may be made in the embodiments described by persons skilled in the art without departing from the scope of the present invention as defined by the following claims. Moreover, no element and component in the present disclosure is intended to be dedicated to the public regardless of whether the element or component is explicitly recited in the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 103128739 A | Aug 2014 | TW | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 20160067791 | Short | Mar 2016 | A1 |
| Number | Date | Country | |
|---|---|---|---|
| 20160052098 A1 | Feb 2016 | US |
