Self Fixturing Assembly Techniques
A process, apparatus, and system for joining at least two workpieces together using at least two adhesives each having substantially different cure times. A first adhesive having a first cure time is used to form a first bond between the two workpieces, the first adhesive having a first cure time. A second adhesive having a second cure time, the second cure time being substantially shorter than the first cure time is used to form a fixturing bond. The fixturing bond maintaining the first and second workpieces in position prior to the first adhesive curing.
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This patent application is related to and incorporates by reference in their entireties for all purposes the following patent applications filed on Oct. 16, 2009:
- (i) U.S. patent application Ser. No. 12/580,914 entitled “PORTABLE COMPUTER DISPLAY HOUSING” by Bergeron et al., now U.S. Pat. No. 8,233,109;
- (ii) U.S. patent application Ser. No. 12/580,985 entitled “PORTABLE COMPUTER ELECTRICAL GROUNDING AND AUDIO SYSTEM ARCHITECTURES” by Thomason et al.;
- (iii) U.S. patent application Ser. No. 12/580,946 entitled “PORTABLE COMPUTER HOUSING” by Casebolt et al.;
- (iv) U.S. patent application Ser. No. 12/580,934 entitled “METHOD AND APPARATUS FOR POLISHING A CURVED EDGE” by Lancaster et al. that takes priority under 35 U.S.C. 119(e) to U.S. Provisional Patent Application Ser. No. 61/249,200 entitled “COMPLEX GEOGRAPHICAL EDGE POLISHING” by Johannessen filed Oct. 6, 2009 and incorporated by reference in its entirety;
- (v) U.S. patent application Ser. No. 12/580,922 entitled “COMPUTER HOUSING” by Raff et al., now U.S. Pat. No. 8,111,505;
- (vi) U.S. patent application Ser. No. 12/580,976 entitled “BATTERY” by Coish et al., now U.S. Pat. No. 8,199,469, which is a continuation in part of U.S. patent application Ser. No. 12/549,570 filed Aug. 28, 2009;
- (vii) U.S. patent application Ser. No. 12,580,886 entitled “PORTABLE COMPUTER DISPLAY HOUSING” by Bergeron et al.; and
- (viii) U.S. patent application Ser. No. 12/580,927 entitled “COMPUTER HOUSING” by Raff et al., now U.S. Pat. No. 8,199,468.
1. Field of the Invention
The described embodiments relate generally to manufacturing assembly operations. More particularly, the present embodiments relate to joining computer sub-assemblies together in a manner that is both operationally efficient as well as preserves the aesthetic aspects.
2. Description of the Related Art
The outward appearance of a portable computing device, including its design and its heft, is important to a user of the portable computing device, as the outward appearance contributes to the overall impression that the user has of the portable computing device. At the same time, the assembly of the portable computing device is also important to the user, as a durable assembly will help extend the overall life of the portable computing device and will increase its value to the user.
One design challenge associated with the portable computing device is the design of the enclosures used to house the various internal components. This design challenge generally arises from a number of conflicting design goals that include the desirability of making the enclosure lighter and thinner, the desirability of making the enclosure stronger and making the enclosure more aesthetically pleasing. The lighter enclosures, which typically use thinner plastic structures and fewer fasteners, tend to be more flexible and therefore they have a greater propensity to buckle and bow when used while the stronger and more rigid enclosures, which typically use thicker plastic structures and more fasteners, tend to be thicker and carry more weight. Unfortunately, increased weight may lead to user dissatisfaction, and bowing may damage the internal parts.
Furthermore, in most portable computing devices, the enclosures are mechanical assemblies having multiple parts that are screwed, bolted, riveted, or otherwise fastened together at discrete points. For example, the enclosures typically have included an upper casing and a lower casing that are placed on top of one another and fastened together using screws. These techniques typically complicate the housing design and create aesthetic difficulties because of undesirable cracks, seams, gaps or breaks at the mating surfaces and fasteners located along the surfaces of the housing. For example, a mating line surrounding the entire enclosure is produced when using an upper and lower casing. Not only that, but assembly is often a time consuming and cumbersome process. For example, the assembler has to spend a certain amount of time positioning the two parts and attaching each of the fasteners. Furthermore, assembly often requires the assembler to have special tools and some general technical skill.
Another challenge is in techniques for mounting structures within the portable computing devices. Conventionally, the structures have been laid over one of the casings (upper or lower) and attached to one of the casings with fasteners such as screws, bolts, rivets, etc. That is, the structures are positioned in a sandwich like manner in layers over the casing and thereafter fastened to the casing. This methodology suffers from the same drawbacks as mentioned above, i.e., assembly is time consuming and cumbersome.
Therefore, it would be beneficial to provide a housing for a portable computing device that is aesthetically pleasing and lightweight, durable and yet environmentally friendly. It would also be beneficial to provide operationally efficient methods for mounting computer sub-assemblies to the housing that preserves the aesthetic look and feel of the housing.
SUMMARY OF THE DESCRIBED EMBODIMENTSThis paper describes various embodiments that relate to systems, methods, and apparatus for mounting computer sub-assemblies to a lightweight, visually seamless housing suitable for use in portable computing applications.
A self-fixturing method for bonding at least two workpieces together is described. The method can be carried out by performing at least the following operations. Forming a first bond between the two workpieces using a first adhesive, having a first cure time and self-fixturing the two workpieces together by bonding the two workpieces together using a second adhesive having a second cure time substantially shorter than the first cure time. In the described embodiment, the second bond is independent of the first bond and enables the self-fixtured workpieces to undergo processing that would otherwise occur only after the first adhesive has cured.
In one aspect, a first one of the workpieces is a plastic computer housing having at least a top cover and formed of a plastic material such as PCABS. A second workpiece is a metal frame formed of magnesium or magnesium alloy having a plurality of attachment features that can take the form of holes in the metal frame. The metal frame providing support for internal components of a computer assembly placed in the computer housing. The first adhesive can be an epoxy having a cure time of about 12-24 hours and the second adhesive can be a UV cure glue having a cure time of about 5 seconds.
In one embodiment, a method for joining a first and second workpiece together is described. The method can be performed by carrying out at least the following operations. Applying a first adhesive to the first workpiece or the second workpiece at an application region, the first adhesive having an associated first cure time; placing the first and the second workpiece in contact with each other at the application region; applying an externally generated compression force to the first and the second workpieces; applying a second adhesive to at least one of the first and second workpieces at an attachment feature, the second adhesive having an associated cure time substantially less than the first cure time; curing the second adhesive; and removing the externally generated compression force.
Computer readable medium encoded with computer program executed by a processor for controlling a manufacturing process for joining a first and second workpiece together is described. The computer readable medium including computer code for applying a first adhesive to the first workpiece or the second workpiece at an application region, the first adhesive having an associated first cure time; computer code for placing the first and the second workpiece in contact with each other at the application region; computer code for applying an externally generated compression force to the first and the second workpieces; computer code for applying a second adhesive to at least one of the first and second workpieces at an attachment feature, the second adhesive having an associated cure time substantially less than the first cure time; computer code for curing the second adhesive; and computer code for removing the externally generated compression force.
Other aspects and advantages of the described embodiments will become apparent from the following detailed description taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the described embodiments.
The embodiments will be readily understood by the following detailed description in conjunction with the accompanying drawings, wherein like reference numerals designate like structural elements, and in which:
Reference will now be made in detail to representative embodiments illustrated in the accompanying drawings. It should be understood that the following descriptions are not intended to limit the embodiments to one preferred embodiment. To the contrary, it is intended to cover alternatives, modifications, and equivalents as may be included within the spirit and scope of the described embodiments as defined by the appended claims.
The following relates to a process, apparatus, and system for joining at least two workpieces together using at least two adhesives each having substantially different cure times. In one embodiment, a first adhesive can have an associated first cure time and a second adhesive can have an associated second cure time that is substantially shorter in duration than the first cure time. For example, the first adhesive can take the form of an epoxy such as LOCTITE® H8000™ having a structural cure time of about 24 hours at room temperature (i.e., about 25° C.) whereas the second adhesive can take the form of a UV cure type adhesive such as LOCTITE® 3106™ having a cure time of about 3-10 seconds to about 30 seconds when exposed to UV light having wavelength in the range of about 280-395 nm. The second adhesive can act to self fixture the first and second workpieces together as a single piece that can immediately undergo subsequent processing without the need for an external fixturing device. In this way, at least an amount of time approximately equal to the difference between the first and second cure times can be saved from the overall processing time.
These and other embodiments are discussed below with reference to
Rear frame 104 can provide support for a rear portion of housing 102 as well as, in some embodiments, a user interface such as a keyboard (shown in silhouette). Rear frame 104 can also act as a platform onto which a number of internal components such as a main logic board, or MLB, optical disk drive, or ODD, and so on can be mounted. Rear frame 104 can be formed of lightweight and strong material along the lines of aluminum, magnesium, or any alloy thereof. In the described embodiment, rear frame 104 and housing 102 can be bonded together using a self fixturing technique in accordance with the described embodiments. For example, to form a first bond, a first adhesive (such as epoxy) having a first cure time can be applied to an inside surface of rear frame 104. However, securing together housing 102 and rear frame 104 using a conventional bonding technique requires that both rear frame 104 and housing 102 be placed in a compression fixture at least until the first adhesive has cured. In this way, rear frame 104 and housing 102 cannot be removed from the compression fixture for further processing at least until after the first adhesive has cured wasting valuable processing time that could otherwise be used for subsequent processing. It should also be noted that compressing housing 102 for any appreciable length of time can also cause deformations and warping in top cover 100.
However, using a self fixturing technique in accordance with the described embodiments, the operational inefficiencies and potential product damage associated with a conventional bonding approach can be essentially eliminated. For example, while the rear frame 104 and housing 102 are still in the compression fixture, a second, or self fixturing, bond that is independent of the first bond can be formed between rear frame 104 and housing 102. The fixturing bond can be formed using a second adhesive having a shorter cure time than the first adhesive. The fixturing bond can be formed by applying a second adhesive at any of a number of attachment features 114 located in rear frame 104. In the described embodiment attachment features 114 can take the form of perforations along the lines of circular holes each having diameter D1 being a size that allows a sufficient amount of surface 106 to be wetted by the second adhesive passing through attachment feature 114. The second adhesive can cure in a period of time much less than the time required for the first adhesive to cure and can form semi-spherical-like plugs 116 each having a diameter D2 that can be greater than diameter D1. In this way, the bond formed by the second adhesive can quickly secure rear frame 104 and housing 102 while still in the compression fixture. However, once the fixturing bond is created, rear frame 104 and housing 102 can be immediately removed from the compression fixture without fear of disturbing the curing of the first adhesive. Moreover, the tight fit and unyielding nature of plugs 116 can help to maintain the compressive force (i.e., sometimes referred to as being “frozen into place”) between rear frame 104 and housing 102 even after being removed from the compression fixture.
A particular embodiment will now be described with reference to
Once epoxy 202 is properly applied to surface 204, rear frame 200 can be removed from epoxy dispensing unit 300 and placed “epoxy side” down onto surface 106 as shown in
While still in compression fixture 500 and with attachment features 114 accessible via access holes 502, second adhesive in the form of UV glue along the lines of LOCTITE® 3106™ can be applied by dispenser unit 504 through access holes 502 each associated with a specific one of attachment features 114. Once the second adhesive is applied, compression fixture 500, housing 102 and rear flame 200 can be placed in a UV cure system that can generate UV light in the range of about 280-395 nm. In this way, the UV glue can cure in about 5 seconds forming plug 600 an example of which is shown in
At 704, the first and second workpieces can be placed in contact with each other at the application area. In this way, the first adhesive can make contact with both the first and the second workpiece. Next, at 706, an externally generated compression force is applied to both the first and second workpieces. In this way, the first adhesive can properly “wet up” between the first and second workpieces so as to at least remove any voids and so on that could have an adverse affect on the bond formed. At 708, a second adhesive having a second cure time that is shorter than the first cure time is applied such that the second adhesive comes in contact with both the first and the second workpieces. It should be noted that the application of the second adhesive can take place while the externally generated compression force is still being applied to the first and the second workpieces. In the described embodiment, the second adhesive can take the form of a UV cure glue having a cure time of about 10 seconds.
At 710, the second adhesive is cured. For example, if the second adhesive is a UV cure glue (such as LOCTITE® 3106™ manufactured by Henkel AG & Co. of Dusseldorf, Germany), then the first and second workpieces can be placed in a UV cure system for at least the amount of time required to cure the second adhesive (about 5 seconds under UV light of about 280-395 nm). Once the second adhesive has fully cured, the externally generated compression force can be removed at 712 and at 714 the conjoined (by virtue of the second bond formed by the cured second adhesive) first and second workpieces can undergo subsequent processing that would otherwise have to wait until at least the first adhesive had cured.
The various aspects, embodiments, implementations or features of the described embodiments can be used separately or in any combination. Various aspects of the described embodiments can be implemented by software, hardware or a combination of hardware and software. The described embodiments can also be embodied as computer readable code on a computer readable medium for controlling assembly operations or as computer readable code on a computer readable medium for controlling a manufacturing line used to fabricate housings. The computer readable medium is any data storage device that can store data which can thereafter be read by a computer system. Examples of the computer readable medium include read-only memory, random-acess memory, CD-ROMs, DVDs, magnetic tape, optical data storage devices, and carrier waves. The computer readable medium can also be distributed over network-coupled computer systems so that the computer readable code is stored and executed in a distributed fashion.
Claims
1. A method for joining a first workpiece and a second workpiece together, wherein the first workpiece has at least one hole, the method comprising:
- applying a first adhesive to the first workpiece at an application region;
- placing the first workpiece in contact with the second workpiece at the application region;
- applying a second adhesive to the first workpiece within the at least one hole; and
- curing the second adhesive before the first adhesive is fully cured.
2. The method defined in claim 1, further comprising:
- performing additional assembly operations after the second adhesive is cured and before the first adhesive is fully cured.
3. The method defined in claim 1 wherein the first workpiece comprises a computer frame and wherein applying the first adhesive to the first workpiece comprises applying the adhesive to the computer frame.
4. The method defined in claim 1 wherein the second workpiece comprises a computer housing and wherein placing the first workpiece in contact with the second workpiece at the application region comprises placing the first workpiece in contact with the computer housing at the application region.
5. The method defined in claim 1 wherein the at least one hole comprises a plurality of attachment features and wherein applying the second adhesive to the first workpiece within the at least one hole comprises applying the second adhesive to the first workpiece within each attachment feature in the plurality of attachment features.
6. The method defined in claim 1 further comprising:
- after placing the first workpiece in contact with the second workpiece at the application region, applying a compression force to the first and second workpieces with a compression fixture.
7. The method defined in claim 6 further comprising:
- after curing the second adhesive, removing the compression force from the first and second workpieces.
8. The method defined in claim 1 wherein the first adhesive comprises an epoxy and wherein applying the first adhesive to the first workpiece at the application region comprises applying the epoxy to the first workpiece at the application region.
9. The method defined in claim 1 wherein the second adhesive comprises UV cure adhesive and wherein applying the second adhesive to the first workpiece within the at least one hole comprises applying the UV cure adhesive to the first workpiece at the application region.
10. A computer assembly, comprising:
- a computer frame having at least one hole;
- a computer housing;
- a first adhesive in contact with the computer frame and the computer housing, wherein the first adhesive has a first cure time; and
- a second adhesive within the at least one hole and in contact with the computer housing, wherein the second adhesive has a second cure time and wherein the first cure time is longer in than the second cure time.
11. The computer assembly defined in claim 10 wherein the first adhesive comprises an epoxy.
12. The computer assembly defined in claim 10 wherein the second adhesive comprises a UV cure adhesive.
13. The computer assembly defined in claim 10 wherein the computer frame comprises metal.
14. The computer assembly defined in claim 10 wherein the at least one hole comprises a plurality of attachment features.
15. The computer assembly defined in claim 10 wherein the second adhesive within the at least one hole forms a plug that presses the computer frame and the computer housing together.
16. A method for forming a computer assembly, comprising:
- forming a first bond between a computer frame and a computer housing using a first adhesive;
- applying a compression force to the computer frame and the computer housing to compress the first adhesive;
- forming a second bond between the computer frame and the computer housing using a second adhesive; and
- after the second adhesive has cured and before the first adhesive has cured, removing the compression force.
17. The method defined in claim 16 wherein forming the second bond comprises applying the second adhesive to a plurality of attachment features in the computer frame to form the second bond between the computer frame and the computer housing at the attachment features.
18. The method defined in claim 16, further comprising:
- performing subsequent processing steps on the computer assembly after the second adhesive has cured and before the first adhesive has cured.
19. The method defined in claim 16 further comprising:
- while applying the compression force to the computer frame and the computer housing, exposing the second adhesive to UV light to cure the second adhesive.
20. The method defined in claim 16 wherein forming the second bond comprises filling at least one hole in the computer frame with the second adhesive to form a plug in the at least one hole, wherein the plug is configured to compress the computer frame against the computer housing while the first adhesive cures.
Type: Application
Filed: Oct 30, 2012
Publication Date: Feb 28, 2013
Applicant: Apple Inc. (Cupertino, CA)
Inventor: Apple Inc. (Cupertino, CA)
Application Number: 13/664,307
International Classification: B32B 37/12 (20060101); B32B 7/12 (20060101); B32B 37/06 (20060101);