FIELD OF THE INVENTION
- BACKGROUND OF THE INVENTION
This invention relates to a joint and method for producing a joint between two components and more particularly to a joint and method that uses micrograms and a fast curing adhesive to provide a fast alignment and joining of two components in precise relationship with one another.
It is known that stable joints can be formed by cementing two or more components in place. However, because the typical curing time for most cements is relatively long (i.e., 5 minutes to several hours or several days), the expensive fixturing equipment holding these components in precise alignment is tied up for a long time, making the equipment unavailable for producing more jointed parts and increasing queue time and assembly. Furthermore, during the long curing time the two component may be inadvertently moved out of alignment and then set in place in that position.
Some methods of joining two or more components utilize a mixture of solid particles and a curable cementing compound to form such joints. For example, U.S. Pat. No. 4,836,967 describes a method for connecting a plurality of bars in a metal casting. This method includes the steps of pouring a granulated solid with grain size of 5 mm to 100 mm to into a metal casing having a centrally located aperture and a plurality of filling apertures, prestressing the solid by driving a mandrill through the filling apertures and injecting a hardening fluid such as a cement based grounding mortar through the central aperture. According to the summary of invention, prestressing the granulated solid results in a very stable joint. However, this step requires extra time during the joint assembly. Furthermore, making a casting with a special central aperture for accepting the hardening fluid and having to cover the central aperture after the hardening fluid is injected into the casing results in an expensive joint. Finally, this patent does not disclose how to achieve a precise alignment of the components relative to one another.
- SUMMARY OF THE INVENTION
U.S. Pat. No. 4,407,770 describes a method for anchoring cables inside a sleeve. This method includes the steps of partially filling the sleeve containing the cables with the curable liquid made of epoxy resin and mineral power, adding the aggregate particles and then, allowing the liquid mixture to cure to a solid mass. However, the epoxy resin/powder mixture takes relatively long time to cure.
It is an object of the present invention to provide a method for accurately positioning two component with respect to one another and then rapidly joining them together while preserving this alignment, forming a solid joint.
It is another object of the present invention to provide a stable joint comprised of two precisely aligned components. According to one aspect of the present invention, a method of forming a joint comprises the steps of: (a) at least filling a container with granular particles, the granular particles having a size of 0.25 mm to 1 mm; (b) inserting a component part into the container; (c) at least partially filling the container containing this component part and the granular particles with a flowable, curable liquid, this liquid having curing time of less than 90 seconds. According to one embodiment of the present invention, the curable liquid has a gap fill of less than 0.25 mm.
According to another aspect of the present invention, a method of forming a joint by connecting at least one component part to a housing having a fill cavity, comprising the steps of: (i) introducing granular solid material having a grain size from 0.25 mm to 1 mm into the fill cavity; (ii) placing at least a portion of the component part into the fill cavity; (iii) applying a hardening fluid into the fill cavity over the granular solid material, wherein the hardening fluid has a gap fill of less than 0.25 mm.
According to one embodiment of the invention, a method of forming a joint by connecting at least one component part to a housing having a fill cavity comprises the steps of: (i) introducing granular solid material having a grain size from 0.25 mm to 1 mm into said fill cavity; (ii) placing at least a portion of the component part into the fill cavity; (iii) aligning the component part with respect to the housing by moving the component part inside the cavity until a desired orientation is achieved; and (iii) applying a hardening fluid into the fill cavity, wherein the hardening fluid has a gap fill of less than 0.25 mm, to lock said component in said desired orientation.
BRIEF DESCRIPTION OF THE DRAWINGS
According to yet another aspect of the present invention, a rigid joint comprises a plurality of components including: (i) a first component having an inner wall defining a fill cavity; (ii) a second component at least partially situated in the fill cavity of the first component; and (iii) a plurality of micrograms located between the inner wall and at least a part of the first component, the micrograms having a size of less than 1 mm. At least a portion of the micrograms is coated with a polymerizing liquid, such that the coated micrograms and the second component are fixably secured in place.
FIG. 1 is a cross-sectional view of a plurality of mechanical components positioned relative to one another.
FIG. 2 is a cross-sectional view of the plurality of mechanical components of FIG. 1 after they have been joined to each other.
FIG. 3 is a perspective view the plurality of mechanical components of FIG. 1 after they have been joined to each other.
FIG. 4 is a cross sectional view of a frame and a frame base positioned relative to one another.
FIG. 5 is a perspective view of the frame of FIG. 4.
FIG. 6 is a perspective view of the frame base of FIG. 4.
FIG. 7 is a cross sectional view of a portion of a frame base of FIG. 4 with a cavity containing micrograms and a side wall portion of the frame of FIG. 4.
DETAILED DESCRIPTION OF THE INVENTION
FIG. 8 is a perspective view of the frame and the frame base after they have been joined to each other.
The present description will be directed in particular to elements forming part of, or in cooperation more directly with, the apparatus in accordance with the present invention. It is understood that elements not specifically shown or described may take various forms well known to those skilled in the art.
Referring to FIGS. 1, 2 and 3, a joint according to the first embodiment of the present invention comprises a first component 10 with a fill cavity 12 and a second component 13 at least partially situated in this fill cavity 12. More specifically, according to the first embodiment of the invention, the second component 13 comprises a block 14 and a post 15. The post 15 fits into the fill cavity 12 of the first component 10 and preferably has a textured outer surface 15A. The fill cavity 12 may have any cross section suitable for receiving the required part (such as the post 15, for example) of the second component 13. The fill cavity 12 should be larger than the portion of the second component 13 that is being inserted into the fill cavity 12. The walls 20 of the fill cavity are also preferably textured.
A plurality of micrograms 16 are poured into the fill cavity 12 and fill the void 18 between the wall 20 of the cavity 12 and the inserted part (i.e., the post 15) of the second component 13. The term “microgram” describes a solid particle that is not larger than 1 mm in its largest dimension. The width d of the void 18 needs to be a minimum of 3 micrograms. It is preferred that the width d be between 1 mm and 15 mm. In this embodiment, the void 18 has a width d of 2.5 mm to 3 mm (FIG. 2.) and the microgram size is about 0.3 mm.
Alternatively, the micrograms 16 are poured into the fill cavity 12 first and then the second component 13, or a part thereof, is pressed into the micrograms 16, displacing the micrograms 16. Either way, the micrograms 16 surround the part of the second component 13 that is situated inside the fill cavity. The micrograms 16 can be glass microspheres, metal microspheres, non spherical metal chips, table salt, sand or the like.
The second component 13, while its post 15 is surrounded by the micrograms 16, is not yet locked in place and can be moved relatively to the first component in six degrees of freedom indicated by arrows 21, 22, 23, 24, 25, 26 (for example, up, down, sideways, and tilted around). Once the proper orientation of the second component 13 is achieved, a fast curing adhesive liquid 28 is applied from a container 29 to the upper surface 30 of the micrograms 16. It is preferred that the liquid 28 is poured rather than dripped onto the top of micrograms 16. This provides better (i.e., deeper) penetration through the micrograms 16 filling the inside of at least a portion of the fill cavity 12. The liquid 28, for example Super Glue, penetrates through at least the the top portion 32 (about 1 mm to 10 mm deep and, preferably, 3 mm to 6 mm deep) of the micrograms 16, coats the micrograms 16, fills the gaps between the micrograms, quickly hardens and locks the second component 13 in position. The curing time of the liquid 28 is less than 90 seconds and preferably less than 75 seconds and more preferably, no more than 30 seconds. It is most preferable that the curing time be no more than 20 seconds. In this specification the term “curing time” is defined as the time required for the liquid 28 to harden so that two components are prevented from further movement relative to one another, without the breakage of the joint.
As stated above, it is preferred that the wall 20 defining the fill cavity 12 and the outer surface 15A of the component 13 that fits inside the fill cavity 12 be textured; for example threaded, or sand blasted. This would provide a better gripping surface for the adhesive to bind with. The micrograms 16 have a size of 1 mm or less and preferably less than 0.5 mm. It is most preferable that the size of the micrograms 16 be between 0.25 mm and 0.5 mm. The small grain size (0.25 mm and 0.5 mm) produces more surface area and thus more bonding area, resulting in higher strength joint. Furthermore, smaller micrograms result in smaller gap areas between the micrograms. This, in turn, results in faster cure times. The fast curing adhesive liquids used with smaller size micrograms 16 should be less viscous in order to fill the smaller sized gaps between the micrograms 16. However, because all adhesive liquids have some viscosity, if the size of the micrograms is less than 0.25 mm the gap area between the micrograms becomes very small, making it hard for the liquid 28 to penetrate into the gaps. This results in weaker joints.
Preferable curing liquids are polymerizing liquids, for example, liquids that undergo anionic polymerization. An example of such liquid is cyanoacrylate adhesive such as a fast curing, single component cyanoacrylate instant adhesive available under the trade name of LOCTITE® PRISM™ 401 from Loctite Corp. of Newington, Conn. Typical curing or fixturing times for adhering to various materials for one of these fast curing liquids are provided below in Table 1. The data for other suitable materials is provided in Table 2. I have used LOCTITE® PRISM™ 401 and the Loctite product number 420 with glass microspheres of about 0.3 mm diameter and achieved a curing time, and thus a stable bond between two steel components 10
, in about 5 seconds or less. Thus, two components can be secured in position quickly, maintaining the required alignment between the two components without disturbing their relative positions.
|TABLE 1 |
|Performance of LOCTITE ® PRISM ™ 401 on metallic and non-metallic |
| ||Material ||Typical Fixturing Time (seconds) |
| || |
| ||G-10 epoxy glass: ||10 |
| ||Steel (degreased): ||13 |
| ||Aluminum (etched): ||6 |
| ||Zinc dichromate: ||60 |
| ||Neoprene rubber: ||5 |
| ||Nitrile rubber: ||5 |
| ||ABS: ||6 |
| ||PVC: ||6 |
| ||Polycarbonate: ||23 |
| ||Phenolic materials: ||10 |
| || |
|TABLE 2 |
|Loctite || || || || || || || |
|Number ||404 ||409 ||414 ||415 ||416 ||420 ||422 |
|Typical ||Rubber ||General ||Plastic ||Gap ||Gap ||Wicking ||Gap |
|Use ||“O” Ring ||Purpose ||Bonder ||Filling ||Filling ||Type ||Filling |
| ||Bonder ||Gel || ||Metal ||Plastic ||Plastic ||Plastic |
| || ||Adhesive || ||Bonder ||Bonder ||Bonder ||Bonder |
|Color ||Clear ||Clear ||Clear ||Clear ||Clear ||Clear ||Clear |
|Gap Fill ||.005″ ||.010″ ||.006″ ||.008″ ||.008″ ||.002″ ||.008″ |
|Resin Base ||Ethyl ||Ethyl ||Ethyl ||Methyl ||Ethyl ||Ethyl ||Ethyl |
|Viscosity cP ||80 ||Gel ||110 ||1500 ||1500 ||2 ||2500 |
|Strength psi ||3,500 ||3,200 ||3,200 ||3,600 ||3,200 ||2,900 ||3,200 |
|Temperature ||−65° F. to ||−65° F. to ||−65° F. to ||−65° F. to ||−65° F. to ||−65° F. to ||−65° F. to |
|Range ||180° F. ||180° F. ||180° F. ||180° F. ||180° F. ||180° F. ||180° F. |
|Cure Speed* ||30 sec. ||75 sec. ||20 sec. ||30 sec. ||30 sec. ||20 sec. ||30 sec. |
|Full cure** ||24 hrs. ||24 hrs. ||24 hrs. ||24 hrs. ||24 hrs. ||24 hrs. ||24 hrs. |
|Specific ||1.09 ||1.10 ||1.05 ||1.09 ||1.05 ||1.05 ||1.09 |
|Technical ||404 ||409 ||414 ||415 ||416 ||420 ||422 |
|Data Sheet |
FIG. 4 illustrates a second embodiment of the present invention. A frame 40 comprising three side walls 42 (FIG. 5) needs to be aligned with the frame base 46 and rigidly attached thereto. According to this embodiment of the present invention, the frame base 46 includes a long and narrow fill cavity 48 formed by the walls 50 (FIG. 6). This fill cavity 48 is filled with the micrograms 16. The side walls 42 of the frame 40 are pressed into the fill cavity 48 and the micrograms 16 are displaced to fill the void between the walls 42 and the walls 50 (FIG. 7). Alternatively, the side walls 42 are inserted into the fill cavity and the micrograms 16 are used to fill the void between the walls 50 and the walls 42. The frame 40 is moved (translated and rotated) until it has the correct orientation relative to the frame base 46. The frame 40 is held in this position by a holding fixture (not shown) and a fast curving liquid 28, for example, LOCTITE® PRISM™ 420, is then poured into the fill cavity 48 on both sides of walls 42. The fast curing liquid 28 seeps at least into the top layer 32 of the micrograms 16, undergoes polymerization, quickly hardens and rigidly secures the frame walls 42 inside the cavity 48 of the frame base 46. The hardening of the fast curing liquid 28 secures quickly the frame 40 in precise orientation with respect to the frame base 40 (FIG. 8). I have achieved a rigid connection between the frame and the frame base in about 5 seconds or less. This is much faster than 5 minutes to several days time required for hardening cementing components typical of the prior art.
It is an advantage of the method of the present invention that it provides an improved method for assembling components that require sizeable movements and precision when positioning and aligning by providing these components with unrestricted movement (six degrees of freedom). The improved process is non-destructive to the alignment because the fast curing fluid 28 does not displace the two components relative to one another. It is also an advantage of the improved method that the components are rapidly and fixably secured to one another without introducing distortion, creep, or other non-desirable changes in position of these components.
Existing technologies that could be replaced with the above described method of the present invention are, for example, complicated and time-consuming mechanical screw adjustments. Although such mechanical screw adjustments could accomplish precision alignments, the cost in parts and labor is very high. The improved method of the present invention can also be used instead of the prior art methods that require filling the void between two components (that have been aligned) with an adhesive that needs to be cured by the ultraviolet light or with long-time curing adhesive such as epoxy resin.
- PARTS LIST
The invention has been described in detail with particular reference to certain preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.
10 First component
12 Fill cavity
13 Second component
15A Outer surface
20 Inner wall
21, 22, 23, 24, 25 26 Directional arrows
29 Liquid container
30 Upper surface
32 Top portion
42 Frame walls
46 Frame base
48 Fill cavity
50 Walls of the frame base