Handling: hand and hoist-line implements – Grapple – Expanding
Reexamination Certificate
1999-11-24
2001-02-13
Kramer, Dean J (Department: 3652)
Handling: hand and hoist-line implements
Grapple
Expanding
C294S115000
Reexamination Certificate
active
06186569
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an apparatus and method for lifting, moving and positioning a workpiece. In particular, it relates to a device and method for lifting a circumferential heater used in the manufacture of silicon ingots by the Czochralski method.
2. Description of the Prior Art
Traditionally, devices used to lift circumferential heaters used in the manufacture of silicon ingots are lowered around the outside edge of the heater. Slider bars are then inserted under the heater, and secured to the lifter. In some instances, a cage is then placed around the heater. Prior devices required an operator to manually place support plates under the heater, attach a cage to the supports, and then attach this apparatus to a lifting device. The heater could then be lifted from the bottom chamber of a Czochralski-type crystal puller machine for machine cleaning or heater replacement. These same devices are also used to place a new heater in the puller machine.
The above device, and similar devices, are appropriate for silicon manufacturing operations. However, they have a number of parts that must be assembled prior to and during the lifting, thereby consuming operator and machine time. This assembly and disassembly results in metal-to-metal contact among the device's parts, within the assembly, potentially damaging the device. Additionally, heat transfer from the heater the lifter, resulting from contact between the heater and the lifter, can cause the lifter to warp, leading to the added cost and time of replacement parts; it also increases the temperature of the lifter, thereby requiring a cooling period before the lifter can be handled.
SUMMARY OF THE INVENTION
In view of the above problems, an object of the present invention is to provide an apparatus and method for lifting and positioning a device, such as a circumferential heater, with reduced operator “hands-on” activity. The present device can be lowered into the center of a circumferential heater, the sling foot pads positioned under the heater, and the heater and lifter combination lifted by a single operator, using a remote control box. The present invention improves on past devices due to an operator's ability to operate it from a distance, reduced metal-to-metal contact, and ease of use.
The present invention also has relatively few parts. This reduces the amount of time an operator must spend setting up and taking down the apparatus, thereby enabling a more efficient process. Additionally, the present invention is, essentially, a one-piece construction after assembly. This helps to control warpage and commensurate part misfits.
Another improvement over the prior art is the present invention's elimination of an exterior cage. As opposed to prior heater-lifting devices, which enclosed the heater within a cage or similar means, the present invention lifts a circumferential heater from within its center void. This interior placement eliminates the need for an exterior cage, thereby reducing operator time, warpage, and heat transfer, as described above.
The present invention also reduces metal-to-metal contact by using polymer-based, ceramic, graphite, carbon composite or equivalent bushings and pads. These pads protect both the lifter and the heater from damage, and keep the lifter cooler than the previous lifter devices. The pads have the additional benefit of not contributing metal contamination to the Czochralski process.
REFERENCES:
patent: 995662 (1911-06-01), Commetti
patent: 2336527 (1943-12-01), Bullington
patent: 2951725 (1960-09-01), Jean
patent: 3442546 (1969-05-01), Bachman
patent: 3574381 (1971-04-01), Ocheltree
patent: 4083593 (1978-04-01), Lynn
patent: 4583275 (1986-04-01), Diaz
patent: 614299 (1926-09-01), None
Anderson Douglas G.
Chin Paul T.
Courson Timothy H.
Kramer Dean J
SEH America Inc.
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